Item 6a
coordination savings as the construction schedules, project-delivery approach, and bidpackaging strategy are refined if Council directs staff to coordinate construction of the two projects.
Table 7 – Construction Escalation (Bridge Project)
Construction Cost Escalation
Base Year (2026) $23,000,000
3% Inflation (2029) $25,100,000
5% Inflation (2029) $26,600,000
8% Inflation (2029) $29,000,000
The Bridge Project expenditure plan shown in Table 8 has been updated to reflect implementation of the recommended VA alternatives. The updated expenditure plan includes additional design service costs necessary to complete the engineering, environmental revalidation, permitting coordination, and plan revisions associated with the recommended project modifications. Construction costs have also been escalated to reflect a potential 2029 construction start, consistent with the possibility of coordinating construction of the Bridge Project with the Interchange Project.
Based on currently identified funding sources and the updated expenditure plan, the Bridge Project is anticipated to have approximately $5.1 million in excess funding, which could potentially be reallocated to support the Interchange Project and reduce future debtfinancing needs. Any such reallocation would require future City Council authorization and would be evaluated after confirming the Bridge Project’s final grant requirements, cost estimate, contingency needs, and construction schedule.
Table 8 – Bridge Project’s Expenditure Plan
Phase Balance 2026-27 2027-28
Design $500,000
Right of Way $1,000,000
Utilities Relocation $777,546
Construction Admin $400,000
Construction Management $3,000,000
Construction $26,600,000
Construction Contingency $4,000,000
Total Per Year $1,500,000 $34,777,546
Grand Total for Project2 $36,277,546
Table 9 – Bridge Project’s Funding Plan
Funding Source Balance 2026-27 2027-28
Local Funds: $6,502,885 $3,500,000 $14,158,406
Capital Outlay (IIF) $4,749,972 $3,500,000 $11,158,406
Capital Outlay (LRM) $1,667,019 $ 3,000,000
Capital Outlay $85,894
Developer Funds: $1,230,906 $0.00 $0.00
2 Summation of Total Per Year row above the Grant Total for Project Row
Item 6a
AASP TIF $135,490
Citywide TIF $1,095,497
Grant Funds: $2,065,000 $0.00 $13,920,349
Earmark $2,065,0003 $58,676.00
Highway Bridge Program $ -
4 $13,861,673
Total Per Year $9,798,791 $3,500,000 $28,078,755
Grand Total for Project $41,377,546
Grant Fund Administrative Adjustments
The Bridge Project is currently funded by two separate grants. The first source of grant funds is the Highway Bridge Program and the second source is Federal Earmark Funds.
The following grant appropriation revisions are included in Staff’s recommendations and documented in Attachment J:
Decrease the Federal Earmark Fund appropriation from $4.130 million to the correct amount of $2.065 million. The City appropriated the $2.065 million maximum grant reimbursement amount through the 2023-25 Financial Plan and inadvertently appropriated the same amount again through the 2025-27 Financial Plan. Because the grant funding only needed to be appropriated once, the recommended adjustment eliminates the duplicate appropriation and accurately reflects the available grant amount.
Decrease the current Highway Bridge Program appropriation from $6 million to $0.
The Highway Bridge Program is a reimbursement grant administered by Caltrans.
Before incurring eligible project costs, the City must complete the required authorization process and receive Caltrans approval to proceed with the applicable phase of work. Costs incurred before authorization, or costs that do not comply with grant requirements, are not eligible for reimbursement. This adjustment does not reduce the approximately $13.861 million in Highway Bridge Program funding currently anticipated for the Bridge Project. Instead, it removes funds that are not yet authorized for expenditure and aligns the appropriation with the anticipated timing of the work. Staff will appropriate the authorized grant amount through a future budget action after Caltrans authorizes the funds for expenditure.
These appropriation revisions are administrative budget corrections and do not change the Bridge Project’s overall funding strategy, reduce the grant funding anticipated for the project, or require an additional General Fund contribution. The revisions accurately reflect the Federal Earmark Fund award amount and the timing of Highway Bridge Program funding authorization. Staff will return to the City Council to appropriate the authorized Highway Bridge Program funds when they become available for expenditure.
3 Earmark Grant Fund balance reflects recommended decrease in appropriated balance of $2.065 million. 4 Highway Bridge Program Grant Fund balance reflects recommended decrease in appropriated balance of $6 million.
Item 6a
The City’s Financial Management Manual requires Council approval before staff submits grant applications exceeding $5,000. Securing grant funding is a primary strategy for reducing the City’s direct cost of delivering the Interchange and Bridge Projects.
Attachment K is a resolution that would authorize staff to pursue and submit eligible grant applications for either or both projects. These are significant transportation investments that will improve safety, mobility, system reliability, and long-term community development along the Prado Road corridor. Because grant opportunities may arise on compressed schedules, advance Council authorization will allow staff to respond promptly while maintaining consistency with the approved project scope, City plans and policies, and applicable grant requirements.
The resolution does not appropriate funding, accept a grant award, authorize expenditures, or commit the City to a local match. If either project receives grant funding, staff will return to the City Council with the award details, proposed budget amendment, required local match, and any requested authority to execute grant documents.
REQUESTED COUNCIL DIRECTION
The recommendations presented in this report are intended to establish the policy and implementation direction necessary to continue advancing the Prado Road Interchange Project and Prado Creek Bridge Replacement Project through final design. Council is requested to provide direction and take action on the following items:
1. Underground Utility District No. 17. Introduce the ordinance establishing Underground Utility District No. 17 within the Prado Road Interchange Project limits to provide the legal and administrative framework for converting designated overhead utility facilities to underground service.
2. Interchange Project Technical Studies. Receive the completed Interchange Project Value Analysis and the draft Bridge Type Selection and Wall Type Selection Reports.
3. Supplemental Project Report. Authorize the Assistant City Manager to approve the final Supplemental Project Report following completion of City and Caltrans technical and environmental review, provided the final document remains substantially consistent with the project scope, purpose, and recommendations presented to Council. Any substantive change would be returned to Council for consideration.
4. Interchange aesthetic theme and gateway identification. Select the preferred aesthetic theme for the Interchange Project (with variations as Council deems appropriate) and provide direction on whether the final design should incorporate formal “San Luis Obispo” identification lettering. All three themes appear capable of receiving Caltrans approval, subject to further refinement and final review. If identification lettering is selected, the existing gateway monument near the Prado Road northbound ramps may need to be removed to comply with Caltrans requirements limiting visible gateway or community identification features along each highway approach.
Item 6a
5. Future Elks Lane Class I shared-use path. Provide direction on whether to evaluate and acquire the additional right-of-way necessary to preserve the opportunity for a future Class I shared-use path along Elks Lane. Planning, design, prioritization, funding, and construction of the facility would be addressed through a future Active Transportation Plan update and Capital Improvement Program process.
6. Bridge Project Value Analysis. Receive the Preliminary Value Analysis Study and approve incorporation of Alternatives 1.0, 5.0, and 6.0 into the final Bridge Project design. Authorize the City Engineer to determine the appropriate implementation of Alternatives 3.0 and 4.0 during final design based on engineering requirements, available utility funding, and coordination with utility owners. Alternatives 2.0 and
7.0 are not recommended for implementation.
7. Coordinated construction schedule. Provide direction on whether to continue evaluating a coordinated construction schedule that would shift the anticipated Bridge Project construction start from summer 2027 to summer 2029 to better align with the Interchange Project. Further evaluation would consider potential construction efficiencies, inflation, grant requirements, permitting, utility coordination, project-delivery risks, and impacts to the traveling public.
8. Bridge Project grant appropriations. Approve the recommended administrative budget revisions to eliminate the duplicate Federal Earmark Fund appropriation and remove the Highway Bridge Program appropriation until Caltrans authorizes the funding for expenditure. These adjustments do not reduce the anticipated grant funding, alter the overall project funding strategy, or require an additional General Fund contribution.
9. Grant application authority for both projects. Adopt the resolution authorizing submission of eligible grant applications for the Interchange and Bridge Projects.
The resolution would authorize grant applications but would not appropriate funds, accept an award, commit the City to a local match, or authorize project expenditures. Any grant award and associated funding commitment would be returned to Council for consideration.
ALTERNATIVES
1. Decline to Establish Underground Utility District No. 17 for the Interchange Project and NOT underground the utilities. The City Council could choose not to introduce the ordinance establishing Underground Utility District No. 17 and instead direct that relocated utility facilities remain overhead. This approach would result in additional utility poles throughout the interchange corridor, increase conflicts with sidewalks, bicycle facilities, landscaping, and retaining walls, reduce the long-term reliability of electrical and communication infrastructure, diminish the visual quality of one of the City's primary gateways, and require redesign of portions of the project to accommodate overhead facilities.
2. Decline to Establish Underground Utility District No. 17 for the Interchange Project and underground the utilities. The City could elect not to establish
Item 6a
Underground Utility District No. 17 and could still pursue undergrounding within the Interchange Project area through individual agreements with utility providers and affected property owners. This approach, however, would rely on voluntary cooperation and separate negotiations rather than the uniform legal and administrative process established by Chapter 13.12. Without a district, the City may have limited ability to require timely conversion of private service connections, establish consistent deadlines, coordinate all affected utilities and properties, or require removal of remaining overhead facilities. Separate agreements could also increase administrative effort, create schedule uncertainty, result in inconsistent treatment among affected properties, and increase the risk that some overhead facilities remain after project construction. Establishing the district provides a clearer and more coordinated process for completing the underground conversion in conjunction with the Interchange Project.
3. Decline the Recommended Value Analysis Modifications for the Bridge Project.
The City Council could direct that the Bridge Project continue through final design without implementing some or all of the recommended Value Analysis (VA) refinements. This approach would increase anticipated construction costs by approximately $5 million while providing limited operational benefit. Higher project costs would increase the City's local funding obligation.
4. Select Different Aesthetic Treatments for the Interchange Project. The City Council may select a different aesthetic theme or provide alternative direction regarding gateway branding, landscaping, architectural treatments, or lighting. Staff can incorporate Council direction during PS&E development however, selecting an alternative aesthetic treatment may require additional aesthetic review by Caltrans.
5. Decline Authorization for Administrative Approval of the Supplemental Project Report. The City Council could require the Supplemental Project Report (SPR) to return for final Council approval following completion of all Caltrans reviews. The SPR is primarily a technical engineering document that formalizes design refinements and technical analyses previously considered by the City Council. Requiring an additional Council hearing following completion of the Caltrans review process could extend the project delivery schedule prior to approval of the final document. If substantive changes to the project scope, purpose, or recommendations occur during Caltrans review, the item could be returned to the City Council for further consideration.
6. Decline the Recommended Budget Adjustments. The City Council could decline the proposed grant appropriation adjustments. The proposed actions are administrative in nature and are intended to align the grant appropriations with reimbursement authorizations. Declining these adjustments could complicate project accounting, reimbursement requests, and future financial reporting but would not affect the overall project budgets or funding levels.
Item 6a
ATTACHMENTS
Interchange Project
A - Draft Ordinance to establish a new Underground Utility District 17 B - Proposed Underground District Overview Map
C - PG&E Franchise Agreement (1978)
D - Final Value Analysis Memorandum
E - Draft Bridge Type Selection Report
F - Draft Wall Type Selection Report
G -Draft Supplemental Project Report
H - Aesthetic Treatments
Bridge Project
I - Preliminary Value Analysis
J - Draft Resolution for Submittal of Budget Adjustment for Prado Creek Bridge Project Interchange and Bridge Project
K - Draft Resolution Authorizing Submittal of Grant Applications for Prado Interchange and Prado Creek Bridge Projects
O ______
ORDINANCE NO. _____ (2026 SERIES)
AN ORDINANCE OF THE CITY COUNCIL OF THE CITY OF SAN LUIS OBISPO, CALIFORNIA, AMENDING SECTION 13.12.040 OF THE SAN
LUIS OBISPO MUNICIPAL CODE TO ESTABLISH A NEW
UNDERGROUND UTILITY DISTRICT 17
WHEREAS, The City of San Luis Obispo wishes to improve the resiliency and appearance of the City by the removal of overhead utilities; and WHEREAS, the limits of the Prado Interchange Project, Specification 2091613 (Project) will require significant overhead utility work during construction; and, WHEREAS, the City and overhead utility purveyors will be able to share undergrounding costs; and,
NOW, THEREFORE, BE IT ORDAINED by the Council of the City of San Luis Obispo as follows:
SECTION 1. The following Subsection 17 of Section 13.12.040 of the San Luis Obispo Municipal Code is hereby added to establish Underground District 17:
17. That portion of Prado Road in the City of San Luis Obispo, County of San Luis Obispo, State of California, described as follows:
COMMENCING at a point on the centerline of Higuera Street that bears South 27° 41' 25" West, 161.18 feet from a found brass pin in monument well marking the intersection of the centerline of Higuera Street with the centerline of the Higuera Street Cul-de-sac as shown on the Record of Survey filed in Book 114 of Records of Surveys at page 89 and on the map of Higuera Commerce Park Tract No. 703 filed in Book 10 of Maps at page 50, in the Office of the County Recorder of said County, from which said brass pin, a found pin in monument well marking the intersection of the centerline of Higuera Street with the centerline of Tank Farm Road as shown on said maps, bears South 27° 41' 25" West, 798.90 feet [South 26° 09' 20" West 798.84 feet per said record of survey]; Thence North 62° 18' 35" West, 42.00 feet to the northwesterly line of Higuera Street; Thence along said line and along the northwesterly line of the offer to dedicate described in the document recorded in Volume 3020 of Official Records at page 1 in the Office of the County Recorder of said County North 27° 41' 44", East 709.93 feet to the beginning of a curve to the left, having a radius of 20.00 feet;
Thence continuing along line and along the southwesterly line of Prado Road, 84 feet wide, along the arc of said curve through a central angle of 90° 37' 00" a distance of 31.63 feet;
Ordinance No. _____ (2026 Series) Page 2
O ______
Thence continuing along the southwesterly line of Prado Road North 62° 55' 10" West, 588.88 feet to a point on the northwesterly prolongation of the south line of the “24’ strip to be dedicated to City of San Luis Obispo” shown on Parcel Map SLO-71-178 filed in Book 6 of Parcel Maps at page 70, in the Office of the County Recorder of said County; POINT OF BEGINNING;
Thence continuing along the southwesterly line of Prado Road, North 62° 55' 08" West, 1035.46 feet to the easterly right of way line of State Highway 101 as shown on the State of California Transportation Agency, Department of Public Works, Division of Highways – District 5, Right of Way Map 05-SLO-101 at post mile 26.9 on Sheet 31 of 32 sheets on file at the District 5 Office;
Thence along said easterly right of way the following two courses:
Thence South 88° 05' 27”, East 56.44 feet to an angle point located 300 feet right of station 718+46.90 as shown on said right of way map;
Thence North 27° 46' 34” West, 60.00 feet to an angle point located 300 feet right of station 719+06.90 as shown on said right of way map and to the northeasterly right of way line of said Prado Road marked by a nail and tag inscribed “LS 4819” in concrete as shown on the Record of Survey filed in Book 65 of Licensed Surveys at page 41 in said Office of the County Recorder;
Thence along said northeasterly right of way line, South 62° 55' 08” East, 1052.37 feet to the southwesterly corner of Parcel 2 of Parcel Map No. SLO-73-495 filed in Book 14 of Parcel Maps at Page 4 in said Office of the County Recorder; Thence South 66° 21' 48" West, 108.52’ to the POINT OF BEGINNING.
The Basis of Bearings for this description is the City of San Luis Obispo horizontal control network, January 2007, between control #8110 and control #8114, having a calculated bearing of South 30º 05’ 40” East. Designated points are published in a control inventory on file with the City of San Luis Obispo.
Containing 86,165 square feet more or less.
Also including that portion of Elks Lane in the City of San Luis Obispo, County of San Luis Obispo, State of California, described as follows:
COMMENCING at a nail and tag inscribed “LS 4819” in concrete marking the northerly corner of the northeasterly right of way line of Prado Road as shown on the Record of Survey filed in Book 65 at Page 41 of Licensed Surveys in the Office of the County Recorder of said County, marking the angle point on the easterly right of way line of State Highway 101, located 300.00 feet right of station 719+06.90 as shown on the State of California Transportation Agency, Department of Public Works, Division of Highways –
Ordinance No. _____ (2026 Series) Page 3
O ______
District 5, Right of Way Map 05-SLO-101 at post mile 26.9 on Sheet 31 of 32 sheets on file at the District 5 Office;
Thence along said easterly right of way line North 16° 17' 06" West, 111.30 feet to an angle point marking the southeasterly corner of the land described in Parcel One of the Relinquishment of State Highway to the County of San Luis Obispo, Road V-SLO-2-E filed in Book 1258 of Official Records at page 19 in the Office of the County Recorder of said County, and the POINT OF BEGINNING;
Thence northeasterly along the easterly line of said Parcel, North 18° 03' 55" East, 108.77 feet;
Thence leaving said Parcel line, North 72° 02' 18" West, 55.00 feet to said State Highway easterly right of way line;
Thence southerly along said right of way line the following three courses:
South 17° 57' 05" West, 22.21 feet;
South 35° 26' 34" West, 104.94 feet;
South 80° 57' 04" East, 87.38 feet to the POINT OF BEGINNING.
The Basis of Bearings for this description is the City of San Luis Obispo horizontal control network, January 2007, between control #8110 and control #8114, having a calculated bearing of South 30º 05’ 40” East. Designated points are published in a control inventory on file with the City of San Luis Obispo.
Containing 7,706 square feet more or less.
Property owners shall be prepared to receive underground services by June 30, 2029.
Overhead facilities shall be removed from public property by June 30, 2035.
Property owners shall not incur any costs required for conversions.
SECTION 2. A summary of this ordinance, approved by the City Attorney, together with names of the Council Members voting for and against it, shall be published at least five days prior to its final passage, in a newspaper published and circulated in this City.
This ordinance will go into effect at the expiration of thirty days after its final passage.
INTRODUCED on the 4th day of August, 2026, AND FINALLY ADOPTED by the Council of the City of San Luis Obispo on the ____ day of _______, 202X, on the following vote:
AYES:
NOES:
Ordinance No. _____ (2026 Series) Page 4
O ______
ABSENT:
___________________________
Mayor Erica A. Stewart
ATTEST:
_______________________
Teresa Purrington
City Clerk
APPROVED AS TO FORM:
_______________________
J. Christine Dietrick
City Attorney
IN WITNESS WHEREOF, I have hereunto set my hand and affixed the official seal of the City of San Luis Obispo, California, on ______________________. ___________________________
Teresa Purrington
City Clerk
DUONG
053-051-033
JK DEWAR
PROPERTIES L.P.
SOUTH HIGUERA STREET
POINT OF BEGINNING
POINT OF COMMENCEMENT
S 62° 18' 35" E 42.00'
S 66° 21' 48" W 108.52' PRADO ROAD
053-041-067
PARCEL 2 - 68/PM/66
WALTER BROS.
CONSTRUCTION CO. INC 053-041-066 PARCEL 1 - 14/PM/4 WALTER BROS. CONSTRUCTION CO. INC 053-051-067
CITY OF SLO
053-051-072
CITY OF SLO
LOT 1
17 MB 71
PARCEL 1
SLAL-91-102
50 PM 51
PARCEL 2
SLAL-91-102
50 PM 51
4018 OR 380
114 LS 89
∆=90° 37' 00" L=31.63' R=20.00'
S 62° 55' 10" E 588.88'
S 27° 41' 44" W 709.93'
161.18'
MONUMENT
PER 114/RS/89
T 805 544-4011 SAN LUIS OBISPO, CA 93401
612 CLARION COURT www.wallacegroup.us F 805 544-4294 DRAWING :
DRAWN BY:
JOB No. :
DATE :
SCALE : ® EXHIBIT "____"
UNDERGROUND UTILITY DISTRICT
COUNTY OF SAN LUIS OBISPO, CA
SHEET 1 OF 2 OF EXHIBIT "____"
1479-0007
1479-0007-LEGL-PRDO
NS
04/15/26
1" = 150'
0 150' 300'
(IN FEET)
75'
GRAPHIC SCALE
1 IN = 150 FT
N
S 27° 41' 25" W 798.90'
MONUMENT
PER 114/RS/89
LEGAL DESCRIPTION AREA
86,165 SQUARE FEET ±
FOUND MONUMENT AS NOTED
LEGEND
For Review 04/15/2026 10:01:20 AM
A
3 A
NAIL AND TAG INSCRIBED "LS 4819"
(65 LS 41)
053-041-071 SAN LUIS OBISPO REGIONAL TRANSIT AUTHORITY 053-041-072 COMMUNITY ACTION PARTNERSHIP OF SLO, INC. 053-041-036 COMMUNITY ACTION PARTNERSHIP OF SLO, INC. 053-041-078 COMMUNITY ACTION PARTNERSHIP OF SLO, INC. 053-041-077 ERB 053-041-076
CITY OF SLO
4' WIDE STRIP
053-041-032
PARCEL 1 - 14/PM/04
PRADO PM LLC
053-051-033
JK DEWAR
PROPERTIES L.P.
053-051-045
CITY OF SLO
PRADO ROAD
POINT OF BEGINNING
N 62° 55' 08" W 1035.46'
S 88° 05' 27" E 56.44'
N 27° 46' 34" E 60.00'
S 62° 55' 08" E 1052.37'
S 66° 21' 48" W 108.52'
STATE HIGHWAY 101
ELKS LANE
T 805 544-4011 SAN LUIS OBISPO, CA 93401
612 CLARION COURT www.wallacegroup.us F 805 544-4294 DRAWING :
DRAWN BY:
JOB No. :
DATE :
SCALE : ® EXHIBIT "____"
UNDERGROUND UTILITY DISTRICT
COUNTY OF SAN LUIS OBISPO, CA
SHEET 2 OF 2 OF EXHIBIT "____"
1479-0007
1479-0007-LEGL-PRDO
NS
04/15/26
1" = 150'
LEGAL DESCRIPTION AREA
86,165 SQUARE FEET ±
FOUND MONUMENT AS NOTED
LEGEND
0 150' 300'
(IN FEET)
75'
GRAPHIC SCALE
1 IN = 150 FT
N
For Review 04/15/2026 10:01:20 AM A
3 A
POINT OF COMMENCEMENT
NAIL AND TAG INSCRIBED "LS 4819"
(65 LS 41)
053-041-071 SAN LUIS OBISPO REGIONAL TRANSIT AUTHORITY
PRADO ROAD
STATE HIGHWAY 101
POINT OF BEGINNING
N 18° 03' 55" E 108.77'
S 17° 57' 05" W 22.21'
S 35° 26' 34" W 104.94'
S 80° 57' 04" E 87.38'
N 16° 17' 06" W 111.30'
ELKS LANE
715
716
717
718
719
720
721
722
723
724
725
726
727
728
N 72° 02' 18" W 55.00'
T 805 544-4011 SAN LUIS OBISPO, CA 93401
612 CLARION COURT www.wallacegroup.us F 805 544-4294 DRAWING :
DRAWN BY:
JOB No. :
DATE :
SCALE : ® EXHIBIT "____"
UNDERGROUND UTILITY DISTRICT
COUNTY OF SAN LUIS OBISPO, CA
SHEET 1 OF 1 OF EXHIBIT "____"
1479-0007
1479-0007-LEGL-ELKS
NS
04/15/26
1" = 150'
LEGAL DESCRIPTION AREA
7,706 SQUARE FEET ±
FOUND MONUMENT AS NOTED
LEGEND
0 150' 300'
(IN FEET)
75'
GRAPHIC SCALE
1 IN = 150 FT
N
For Review 04/15/2026 10:01:20 AM 3
A
3 A
ORDINANCE NO . 767 (1978 Series )
AN ORDINANCE OF THE CITY OF SAN LUIS OBISPO
GRANTING TO PACIFIC GAS AND ELECTRIC COMPANY ,
ITS SUCCESSORS AND ASSIGNS, THE FRANCHIS E
(1) TO USE, FOR TRANSMITTING AND DISTRIBUTIN G
ELECTRICITY SUITE D
FOR LIGHTING BUT FOR USE BY CONSUMERS FOR ANY
AND ALL LAWFUL PURPOSES OTHER THAN LIGHTING ,
ALL POLES, WIRES, CONDUITS AND APPURTENANCE S
WHICH ARE NOW OR MAY HEREAFTER BE LAWFULLY
PLACED AND MAINTAINED IN THE PUBLIC STREET S
AND PLACES WITHIN THE CITY OF SAN LUIS OBISPO ,
UNDER THAT CERTAIN FRANCHISE OF GRANTEE AC -
QUIRED PURSUANT TO SECTION 19 OF ARTICLE XI
OF THE CONSTITUTION OF THE STATE OF CALIFORNIA ,
AS SAID SECTION EXISTED PRIOR TO ITS AMENDMENT
ON OCTOBER 10, 1911 ; (2) TO CONSTRUCT, MAINTAIN
AND USE IN SAID PUBLIC STREETS AND PLACES AL L
POLES, WIRES, CONDUITS AND APPURTENANCES WHEN -
EVER AND WHEREVER SAID CONSTITUTIONAL FRANCHIS E
IS NOT NOW NOR SHALL HEREAFTER BE AVAILABL E
THEREFOR, NECESSARY TO TRANSMIT AND DISTRIBUT E
ELECTRICITY SUITED
FOR, AND FOR USE BY CONSUMERS FOR, ANY OR ALL
LAWFUL PURPOSES ; AND (3) TO UTILIZE SAID POLES , '
WIRES, CONDUITS AND APPURTENANCES IN SAID PUBLI C
STREETS AND PLACES FOR TRANSMITTING ELECTRICIT Y
_ FOR USE OUTSIDE THE
BOUNDARIES OF THE CITY FOR ANY AND ALL LAWFUL
PURPOSES, AND PROVIDING THE TERMS AND CONDITION S
OF THE FRANCHISE SO GRANTED .
BE IT ORDAINED by the Council of the City of San Lui s
Obispo as follows :
AG :ktm 3/8/7 8
rev .6 7
rev . 4/78
O 767
SECTION 1 . DEFINITIONS .
Whenever in this ordinance the words and phrases herein - after in this section defined are used, they shall have th e respective meanings assigned to them in the following definitions :
(a) The word "grantee" shall mean Pacific Gas and Electri c Company, and its lawful successors or assigns ;
(b) The word "city" shall mean the City of San Lui s
Obispo, a municipal corporation of the State of California , in its present incorporated form or in any later reorganized , consolidated, enlarged or reincorporated form ;
(c) The word "streets" shall mean the public streets, ways , alleys and places as the same now or may hereafter exis t within city, including State highways, now or hereafte r established within city, and freeways hereafter establishe d within city ;
(d) The phrase "poles, wires, conduits and appurtenances " shall mean poles, towers, supports, wires, conductors, cables , guys, stubs, platforms, crossarms, braces, transformers , insulators, conduits, ducts, vaults, manholes, meters, cut - outs, switches, communication circuits, appliances, attachments, appurtenances and, without limitation to the foregoing , any other property located or to be located in, upon, along , across, under or over the streets of city, and used or usefu l in transmitting and/or distributing electricity .
(e) The phrase "construct, maintain and use" shall mea n to construct, erect, install, operate, maintain, use, repair , or replace ;
AG :ktm 3/8/78 -2 -
rev .6/5/78
(f) The phrase "constitutional franchise" shall mean th e right acquired through acceptance by grantee or its predecessor in estate of the offer contained in the provision s of Section 19 of Article XI of the Constitution of the
State of California, as said section existed prior to it s amendment on October 10, 1911 .
SECTION 2 . GRANT OF FRANCHISE .
The franchise (1) to use, for transmitting and distributing electricity suited for lighting but for
use by consumers for any and all lawful purposes other than lighting , all poles, wires, conduits and appurtenances which are now or ma y hereafter be lawfully placed and maintained in the streets withi n city under the constitutional franchise of grantee ; (2) to construct , maintain and use in said streets all poles, wires, conduits an d appurtenances whenever and wherever the constitutional franchis e of grantee is not now nor shall hereafter be available therefor , necessary to transmit and distribute electricity suited for, and fo r use by consumers for, any or all lawful purposes ; (3) to utiliz e said poles, wires, conduits and appurtenances in said publi c streets and places for transmitting electricity for use outside th e boundaries of city for any and all lawful purposes is hereb y granted to Pacific Gas and Electric Company, its successors an d assigns .
AG :ktm 3/8/78 -3 -
rev .6/5/7 8
rev .7/24/78 Page 173 of 1065
SECTION 3 . RELOCATION OF FACILITIES .
Grantee of this franchise shall relocate, without expens e to city, any poles, wires, conduits and appurtenances theretofor e installed, and then maintained or used under this franchise, i f and when made necessary by any lawful change of grade, alignmen t or width of any streets by city, including the construction of an y subway or viaduct, or any other conflict with a municipal government purpose .
SECTION 4 . TERM .
Said franchise shall be indeterminate, that is to say , said franchise shall endure in full force and effect until th e same shall, with the consent of the Public Utilities Commissio n of the State of California, be voluntarily surrendered or abandoned by grantee, or until the state or some municipal or publi c corporation thereunto duly authorized by law shall purchase b y voluntary agreement or shall condemn and take under the powe r of eminent domain, all property actually used and useful in th e exercise of said franchise and situate in the territorial limit s of the state, municipal or public corporation purchasing or condemning such property, or until said franchise shall be forfeite d for noncompliance with its terms by grantee .
SECTION 5 . CONSIDERATION .
Grantee of said franchise shall during the term thereo f pay to city a sum annually which shall be equivalent to two percen t (2%) of the gross annual receipts of grantee arising from the use , operation or possession of said franchise ; provided, in case th e AG :ktm 6/5/78 -4-
State Legislature raises the minimum percentage allowable, th e new rate shall apply ; and provided, however, that such paymen t shall in no event be less than a sum which shall be equivalent t o one-half percent (1/2%) of the gross annual receipts derived by grantee from the sale of electricity within the limits of city unde r said franchise and said constitutional franchise .
In addition to the foregoing, grantee shall pay to cit y within thirty (30) days of the issuance by the Public Utilitie s Commission of a certificate of convenience and necessity t o exercise the franchise the sum of Ten Thousand Dollars ($10,000 .00) .
If, at any time after the payment of said sum, it shall be adjudge d that said franchise did not become effective or was or is invalid , or if the grantee shall, at any time, be prevented by the city o r by judgment procured by any other person from exercising the same for any reason other than noncompliance with its terms by th e grantee, then said sum of Ten Thousand Dollars ($10,000 .00) shal l be forthwith repaid by the city to the grantee .
SECTION 6 . REPORTS .
Grantee shall file with the City Clerk within three (3 ) months after the expiration of the calendar year, or fractiona l calendar year, following the date of the granting hereof, an d within three (3) months after the expiration of each and every calendar year thereafter, a duly verified statement showing i n detail the total gross receipts of grantee during the precedin g calendar year, or such fractional calendar year, from the sal e of energy within city . Grantee shall pay to city within fiftee n (15) days after the time for filing such statement, in lawfu l AG :ktm 3/8/78 -5 -
rev . 6/5/78
money of the United States, the aforesaid percentage of its gros s receipts for such calendar year, or such fractional calendar year , covered by such statement . Any neglect, omission or refusal b y grantee to file such verified statement, or to pay said percentag e at the time and in the manner specified, shall be grounds for the declaration of a forfeiture of this franchise and of all right s of grantee hereunder .
SECTION 7 . AUTHORITY FOR GRANT .
This franchise is granted under the Indeterminat e
Franchise Act of 1937 and pursuant to Article XIII of the Charte r of the City of San Luis Obispo, adopted in 1955, and no othe r authority .
SECTION 8 . COMPLIANCE WITH LAWS .
All facilities or equipment of grantee that grantee shal l construct, maintain and use or remove, pursuant to the provisions of the franchise granted herein shall be accomplished in accordanc e with the ordinances, rules and regulations of city now or as here - after adopted or prescribed which are not in conflict with th e paramount authority of such rules, regulations and orders as ar e promulgated or approved by or are filed with the Public Utilitie s Commission or other governmental authority having jurisdiction i n the premises .
SECTION 9 . ADMINISTRATIVE PRACTICES .
Grantee is herewith charged with the responsibility o f preparing, with the cooperation of city, a manual of administrativ e AG :ktm 6/5/78 -6-
practices which shall govern the installation and removal of grantee' s facilities in the streets of city which shall include, but not b e limited to, cathodic protection practices . Once each year, commencing with the first full calendar year of the franchise grante d herein, it is to be the joint responsibility of grantee and city to review and update such administrative practices . Both grantee and city are charged with the duty to review and update such administrative practices by a method of mutual cooperation which shal l take into consideration the reasonable needs and convenience o f each party ; provided that said administrative practices and th e terms and conditions thereof shall be at all times subject t o approval of the City Council as expressed by appropriate legislative action, and shall not conflict with the paramount authorit y of such rules, regulations and orders as are promulgated or approve d by or are filed with the Public Utilities Commission or other govern - mental authority having jurisdiction in the premises .
Following the preparation of said manual, and its approva l by the City Council, it shall govern the practices of the grante e in its installation and removal of grantee's facilities in th e streets of city .
SECTION 10 . CITY RESERVED POWERS .
(a) City reserves the right for itself to lay, construct , erect, install, use, operate, repair, replace, remove, relocate , regrade or maintain below surface or above surface improvement s of any type or description in, upon, along, across, under or ove r the streets of the city . City further reserves the right to re - locate, remove, vacate or replace the streets themselves . If the AG :ktm 6/5/78 -7-
necessary exercise of the aforementioned reserved rights is made necessary in order to accommodate a municipal government purpos e and conflicts with any poles, wires, conduits and appurtenance s of grantee constructed, maintained and used pursuant to the pro - visions of the franchise granted hereby, whether previously constructed, maintained and used or not, grantee shall, without cos t or expense to city after written notice from the City Administativ e Officer, or his designated representative, and request to do so , begin the physical field construction of changing the location o f all facilities or equipment so conflicting . Grantee shall procee d promptly to complete such required work .
(b) Irrespective of any other provision of this ordinance , grantee's right to construct, maintain and use, or remove poles , wires, conduits and appurtenances thereto shall be subject at al l times to the right of city, in the reasonable exercise of it s police power in response to a direct and immediate threat to th e health or safety of the public, to require the removal or relocatio n of said poles, wires, conduits and appurtenances thereto at th e sole cost and expense of grantee .
SECTION 11 . REPAIR COSTS .
Grantee shall pay to city on demand the cost of al l
repairs to city property made necessary by any of the operation s of grantee under the franchise granted hereby ; provided, however , that grantee may make repairs to streets, sidewalks, curbs an d gutters itself at its own cost in accordance with city specifications if the same can be done without undue inconvenience t o the public use of the streets .
AG :ktm 6/5/78 -8-
SECTION 12 . FORFEITURE .
This franchise is granted upon each and every conditio n herein contained, and shall be strictly construed against grantee .
Nothing shall pass by the franchise granted hereby to grante e unless it be granted in plain and unambiguous terms . Each o f said conditions is a material and essential condition to th e granting of the franchise . If grantee shall fail, neglect o r refuse to comply with any of the conditions of the franchis e granted hereby, and if such failure, neglect or refusal shal l continue for more than thirty (30) days after written deman d by the City Administrative Officer for compliance therewith, the n city, by the City Council, in addition to all rights and remedie s allowed by law, thereupon may terminate the right, privilege an d franchise granted in and by this ordinance, and all the rights , privileges and the franchise of grantee granted hereby shal l thereupon be at an end . Thereupon and immediately, grantee shal l surrender all rights and privileges in and to the franchise grante d hereby . No provision herein made for the purpose of securing th e enforcement of the terms and conditions of the franchise grante d hereby shall be deemed an exclusive remedy or to afford the exclusive procedure for the enforcement of said terms and conditions , but the remedies and procedure outlined herein or provided, includin g forfeiture, shall be deemed to be cumulative .
SECTION 13 . ACQUISITION AND VALUATION .
Nothing in this ordinance or in the franchise grante d
hereby shall be construed as in any way impairing city's right s AG :ktm 6/5/78 -9-
to acquire property of grantee through the exercise of city' s power of eminent domain, or through voluntary agreement betwee n city and grantee . In the event that city chooses to exercis e its power of eminent domain, it shall do so in accordance wit h the procedures provided by the general law of the State o f California for the condemnation of public utility property .
The valuation of such property for condemnation purposes shal l be made in accordance with such general law .
SECTION 14 . UNDERGROUNDING .
(a) It is the city's intent to underground all utilitie s as expeditiously as possible .
(b) Presently, grantee is engaged in a program of converting to underground certain of its facilities in accordanc e with Decision No . 73078 of the California Public Utilities Commission . At this time, said decision requires grantee to budge t prior to the end of each calendar year, certain sums of money fo r said program for the next succeeding year and allocate these sum s to undergrounding projects in the various governmental jurisdictions throughout grantee's entire service territory on th e basis of the number of customers in each governmental jurisdiction .
Grantee shall at all times use its best efforts to accomplish a s much conversion in the city as may be accomplished through the allocation or reallocation of funds by the California Publi c Utilities Commission pursuant to Rule 20 .
AG :ktm
rev . 7/24/78 -10-
(c) In addition to the foregoing, grantee agrees to permit city to install its conduits in grantee's trenches upon payment of city's proportionate share of trenching costs . Sai d conduits shall include, but not be limited to, conduits fo r street lighting, traffic signals and fire alarm systems .
SECTION 15 . HOLD HARMLESS .
Grantee of the franchise granted hereby shall indemnify , save and hold harmless, city and any officers and employees thereo f against and from all damages, judgments, decrees, costs and expenditures which city, or such officer or employee, may suffer, o r which may be recovered from, or obtainable against city, or suc h officer or employee, for, or by reason of, or growing out of o r proximately resulting from the exercising by grantee of any or al l of the rights or privileges granted hereby, or by reason of an y act or acts of grantee or its servants or agents in exercisin g the franchise granted hereby, and grantee shall defend any sui t that may be instituted against city, or any officer or employe e thereof, by reason of or growing out of or proximately resultin g from the exercise by grantee of any or all of the rights or privileges granted hereby, or by reason of any act or acts of grantee , or its servants or agents, in exercising the franchise grante d hereby .
SECTION 16 . EFFECTIVE DATE .
This ordinance shall become effective thirty (30) day s after its final passage unless suspended by a referendum petitio n filed as provided by law .
AG :ktm 6/5/78 -11-
SECTION 17 . WRITTEN ACCEPTANCE .
The franchise granted hereby shall not become operative until written acceptance thereof shall have been filed by th e grantee with the City Clerk .
SECTION 18 . PUBLICATION AND PUBLICATION COSTS .
This ordinance, together with the ayes and noes, shal l be published once in full, at least three (3) days prior to it s final passage in the Telegram-Tribune, a newspaper publishe d and circulated in said city .
The grantee of said franchise shall pay to the city a
sum of money sufficient to reimburse it for all publicatio n expenses incurred by it in connection with the granting thereof ; such payment to be made within thirty (30) days after the cit y shall have furnished such grantee with a written statement o f such expense .
INTRODUCED AND PASSED TO PRINT by the Council of the Cit y of San Luis Obispo at a regular meeting thereof held on the 18t h day of July , 1978, on motion of Councilman Jorgensen, seconde d by Councilman Settle , and on the following roll call vote :
AYES : Councilmen Dunin, Jorgensen, Petterson, Settle & Mayor Schwart z NOES : None
ABSENT : Non e
ATTEST :
AG :ktm 3/8/7 8
rev .6/5/78
-12- Page 182 of 1065
Approved as to form : Approved as to content :
WENDT, MITCHELL, SINSHEIMER ,
de la MOTTE & LILLE Y
City Attorney
By Allen Grimes
'C ;;Ir<31
City Administrate Office r
Director of Public Service s
AG :ktm 6/5/78 -13 -
ORDINANCE NO . 76 7
FINALLY PASSED this 1st day of August , 1978 ,
on motion of Councilman Settle seconded by
Councilman Jorgensen on the following roll call vote :
AYES : Councilmen Jorgensen, Petterson, Settle and Mayor Schwart z NOES : None
ABSENT : Councilman Duni n
ATTEST :
Project Number • Month Year • Client
Project Name • 1
Supplemental Value Analysis Memorandum
Date: June 3, 2026
Project: 05-1H640 US101 and Prado Road Interchange
To: Mr. Matt Horn, PE, City Major Projects Manager
City of San Luis Obispo
From: Dace Morgan, PE
Re: Supplemental Value Analysis Memorandum
Introduction
The City contracted with Consor to review, validate, and develop additional value analysis recommendations for the US101 and Prado Road Interchange project. The goal was to review the Hybrid Value Analysis (VA) prepared by VMS in the Spring 2023 and implement recommendations, as appropriate.
In addition, Consor's scope included conducting three design charrettes with City and Caltrans staff to examine if additional value items could be realized. The Consor team included a traffic sensitivity study to test the sensitivity of the number of traffic lanes required (width) and configuration of the Prado Road corridor. The team approached the project area from a functional use and context perspective and divided the limits into three segments that make up the corridor from Dalidio Drive to Higuera Street. The team looked at several configuration scenarios and ran hydraulics modeling to optimize the layout of the supports for the overcrossings and ramp structures. The outcome of the design charrettes, completing a traffic sensitivity analysis using the current future City land uses, and further refinement of the hydraulics and structures layout, the team was able to realize approximately $20 million in savings to the project.
Hybrid Value Analysis
The City realized that the construction cost of the US101 and Prado Road Interchange was becoming prohibitively expensive. In the Spring of 2023, the City hired VMS to facilitate and prepare a Hybrid Value Analysis with the goal of looking for opportunities to reduce overall project costs and make schedule saving recommendations. The VA team identified the following items to be considered by the design team:
1. Reduce the maximum speed on Prado Road to 35 mph (this was implemented as part of the PA&ED and Caltrans approved the Design Standard Decision Document for this revision)
2. Reduce lane and shoulder widths where practical
3. Use CIDH columns in lieu of driven piles and pile caps
4. Use longer spans and fewer columns with precast I-girders in lieu of CIP griders
5. Leave existing sewer main on current Elks Lane alignment in lieu of relocation (this was rejected by project stakeholders and was not implemented)
6. Utilize recycled and/or reclaimed materials in project
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US101 and Prado Road Interchange • 2
The decision was made to implement the appropriate and applicable recommendations during the PS&E phase of the project and not incorporate them into the PA&ED phase. Once under contract, Consor reviewed the recommendations and discussed the implementation of them with City staff. City staff indicated that items 1 - 4 and 6 should be implemented to the extent possible.
Revalidation of Value Analysis
Consor began developing conceptual roadway and structure layouts to incorporate the recommendations from the previous VA work. As part of the revalidation phase, Consor conducted three design charrettes that included City staff (Wyatt Banker-Hix, Luke Schwartz, Brian Nelson), Caltrans (Paul Valadao), and Consor team (Brent Lemon, Dace Morgan, Brent Harrison, Scott McCauley, Jim Damkowitch (DKS), and Brian Ray (Sunrise)). The purpose of the design charrettes was to review VA recommendations and look at the Prado corridor through a performance-based design approach instead of the more traditional capacity/demand design theories. The project stakeholders determined performance criteria and ranking the criteria. The most important criteria were to not impact the operations of US101 mainline (i.e. no back up on US101 mainline), reduce crash severity on Prado, Mainline Ramp merge and diverge, Pedestrian level of stress, Emergency Vehicle response, and Safety queueing issues. The least important criteria were vehicular Delay during non-peak periods, Goods movement at Prado Road and Elks Lane Intersection, and Level of Service. With these criteria defined, the team prepared a traffic sensitivity analysis and compared a four-lane corridor with a two-lane corridor and roundabout and signal intersection controls. See attached performance ranking matrix.
New AM and PM peak traffic counts were collected at 15 locations (see attached Supplemental Traffic Operations Memorandum for locations) in May 2025 by the Consor team. These counts included bikes and pedestrians. The peak hour volume sets used for this work were based on the most recent travel demand modeling developed by Central Coast Transportation Consultants on behalf of the City and included the current land use build out of the City's general plan. The travel demand outputs were post-processed using the May 2025 counts. For 2050, the ped and bike counts were manually adjusted to reflect the anticipated increase in bike and ped activity as a result of the project improvements.
Reducing the entire Prado corridor to two lanes resulted in unacceptable delays and congestion that spilled back to Higuera (PM peak) to the east and the Froom Ranch roundabout (AM peak) to the west. Through iterations, it was determined that a four-lane section from the Higuera/Prado intersection to the NB ramp terminal intersection and then a two-lane section from the NB ramp terminal to the Froom Ranch/Dalidio Drive roundabout would result in acceptable operations during peak and non-peak hours. The Prado corridor would experience some delays and congestion in the peak hours starting in 2045, assuming full land use build out of the City's current general plan.
As part of the design charrette process, the design team proposed replacing the combination sidewalk and Class IV protected bike paths on both sides of the corridor with a multi-use bidirectional pathway on the south side of Prado and a 6-foot-wide sidewalk on the north side of Prado Road. This cross section for bikes and pedestrians closely matches the facilities throughout the San Luis Ranch development.
On Nov 4, 2025, the City Council approved the reconfiguration of the Prado Road corridor from Higuera Street to Froom Ranch/Dalidio Drive roundabout. The City approved reconfiguration is shown in Figure 1 below:
D218721CA.00 • June 2026 • City of San Luis Obispo
US101 and Prado Road Interchange • 3
Figure 1: Preferred Alternative - 2-lane overcrossing
The construction cost for the bridge and roadway improvements in 2026 dollars with a 30% contingency was approximately $80 million.
Structures Value Analysis
The largest cost of the project is the bridge structure. During our preliminary analysis, Consor determined that for every 1 foot of width of bridge structure reduced, the construction cost would be reduced by approximately $500,000. Therefore, the team focused on narrowing the bridge structure with the reduction of lane widths, number of lanes, and the reconfiguration of the multi-modal features. The VA recommended lengthening spans from the 100-foot spans in the PA&ED phase. Consor increased the span lengths to 150 feet for the Prado Road structures. We also made it a priority to eliminate a support within the US 101 center median to simplify construction and impacts to Caltrans.
Realizing that bridge spans are more costly than retaining walls and the project area is within a FEMA floodplain, the Consor team began developing and refining the hydraulics model for the project while trying to balance increases to the 100-year water surface elevation, construction costs of a fully elevated structure, and visual impacts. Through optimization, the design team was able to reduce the total amount of bridge structure from approximately 2,550 feet (as conceived in the Project Report) to approximately 1,250 feet. Retaining walls would be utilized where feasible at the western and eastern ends of the Prado Road overcrossings and at the beginning and the end of the northbound ramp structures. During the hydraulics modeling, it was determined that placing the northbound ramp terminal intersection on an island enclosed by octagonal retaining structure (MSE island wall) minimized floodplain impacts to the southeast side of the project.
The MSE island wall splits the overcrossing and the northbound ramps into four separate structures, provides cost savings, reduces long term maintenance for the bridge structures, and more predictable seismic performance as compared to the previously proposed structure and more complex elevated intersection.
The bridge superstructure types will be finalized during the Bridge Type Selection process. Currently, the team is proposing two superstructure types, a cast-in-place (CIP) concrete post tension box girder and a precast prestressed (PC/PS) California wide flange girder. Both structure types provide a cost-effective solution for the overcrossing of US 101. The PC/PS option would not require falsework over US 101 during construction; however, the CIP option provides flexibility for incorporating the flare for the northbound ramp intersection and the CIP would be consistent with the adjacent Prado Interchange structures and other interchange structures in the area. The eastern Prado Road overcrossing and the northbound ramp structures are better suited for the CIP option.
The bridge is recommended to be supported on large diameter cast-in-drilled hole (CIDH) piles. This is consistent with the previously prepared VA study recommendations.
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US101 and Prado Road Interchange • 4
Hydraulics and Hydrology Modeling
A two-dimensional (2D) hydraulic model was developed to assess pre- and post-Project conditions for the base flood. Areas within the project, such as the Prado Road intersection with the northbound ramps and Elks Lane, along Elks Lane, and portions of the northbound off-ramp have experienced flooding in the past.
The hydraulic modeling results for the Project indicate that the flooding along the northbound ramps and along Prado Road would be alleviated, the proposed bridge structures have adequate freeboard in both the 100-year and 50-year flood events.
The hydraulic modeling results indicated the average water surface elevation (WSE) increases of 0.1 foot or less along FEMA cross sections, which meets both City and FEMA standards and are insignificant impacts.
There are point locations of larger WSE increases at the Water Resources Recovery Facility (WRRF) (0.7 feet increase) and an area adjacent to the western end of the project (2.4 feet). This area will likely require additional hydraulic analysis and grading during the PS&E phase of the project.
The new bridge structures and walls are being designed to accommodate the proposed scour for both the 100-year base flood and the 200-year check flood event. The design criteria is that the bridge maintain stability during the 200-year check flood event.
Stormwater Management and Drainage Considerations
Stormwater management and drainage were two items that were not developed as part of the PA&ED phase of the project. As part of Phase I, the Consor Team prepared mapping to identify the existing drainage patterns within the project footprint. This allowed the design team to better understand the existing and historic drainage patterns and determine a baseline for the future project improvements and their impact on the existing stormwater features. It was determined that there is currently flow from public roads flowing into stormwater treatment and retention basins that were constructed as part of the RTA, Homeless Service Center, and WRRF improvements. Because the RTA and Homeless Service Center constructed portions of the new realigned Elks Lane, their developments treated the stormwater in basins within their property. This is similar to the approach taken as part of the WRRF improvements. See attached map for existing drainage patterns within the project footprint.
The proposed project will result in 0.94 acres of net new impervious surface (NNI) and 1.42 acres of replaced impervious surface (RIS) within Caltrans’ right-of-way; and 1.73 acres of NNI and 2.86 acres of RIS within City’s right-of-way. Additionally, there will be 0.14 acres of bike lane on existing roadway within Caltrans’ right-of-way, which are exempted from NIS. The Project will lose 0.03 acres of treated impervious area from existing treatment BMPs. Therefore, the Project is required to treat 2.25 acres of new impervious surface (NIS) within Caltrans’ right-of-way, and 4.59 acres of NIS within City’s right-of-way. The table below shows the breakdown of the impervious surfaces and treatment goal for the project within Caltrans’ and City’s rights-of-way. The current analysis indicates that overall, the project is treating a surplus amount of impervious area; however, the treatment area within the Caltran’s right of way is greater than required while the area within City’s right of way is at a deficit. The City’s existing basins will receive an additional
2.12 acres new impervious areas in total; and the design team currently assumes the basins have the sufficient capacity to accommodate the additional treatment at this phase. The City’s Stormwater Control Measures are currently receiving 0.46 acres of impervious area from Caltrans’ right-of-way, which the City is not currently taking credit for. The proposed project is located next to developed areas such as Regional Transit Authority, 40 Prado Homeless Service Center, and City of San Luis Obispo Water Resource Recovery Facility, constraining the project to a limited area for proposed treatment. The design team will be working
D218721CA.00 • June 2026 • City of San Luis Obispo
US101 and Prado Road Interchange • 5
with City and Caltrans staff in the PS&E phase of the project to determine the acceptability of the proposed stormwater treatment solution.
Disturbed
Soil Area
(acre)
Net New
Impervious
Area (acre)
Replaced Impervious
Area (acre)
New Impervious
Area (acre)
Post-Construction
Treatment Area (acre)
Caltrans 6.87 0.94 1.42 2.22* 2.25**
City 6.39 1.73 2.86 4.59 4.59
Total 13.26 2.67 4.28 6.81 6.81
*Excludes 0.14 acres for bike paths
**Includes additional treatment area of 0.03 acres
New storm drain facilities will be constructed as part of the project. A new system will be installed in the area of the new Prado Road/Elks Lane intersection, modifications will be made to the existing storm drain system near the existing northbound on-ramp/existing Elks Lane intersection to allow stormwater to continue to flow to the low point between the northbound off-ramp and northbound US 101. This water will be treated in BMP No. 1. See attached exhibit for locations of the proposed storm drain systems.
City Wet Utility Relocations
The VA contemplated not relocating the City's sewer main to the realigned Elks Lane. This recommendation was ultimately rejected by the project stakeholders. The Consor design team has met with City Utilities staff to discuss their relocation plans for both the sewer and water mains in the vicinity of the project. Currently, the design includes relocating sewer and water along the new alignment of Elks Lane. With the realignments, City Utility staff will be able to access and maintain these important services without being impeded by the new Prado Road overcrossing. The construction cost for the relocation of these services is approximately $3,000,000. See attached exhibit for the relocation of the City's sewer and water facilities.
In April 2026, Consor evaluated four alternatives to address impacts to the existing 12-inch diameter water crossing of US 101 near the Prado Road interchange. The construction of the MSE Island at the northbound ramp intersection will place the existing 12-inch ductile iron pipe under excessive fill material presenting a challenge for future maintenance. The transmission line is required to maintain critical east– west water system connectivity for the City. The analysis looked at alternatives for reconstructing the crossing including factors such as constructability, cost, operational impacts, permitting/easements, and long-term maintenance.
Four options were evaluated to address the transmission main crossing. Option 1 proposes a trenchless jack-and-bore installation beneath US 101 outside of the project area, minimizing surface disruption but requiring specialized construction, Caltrans permitting, additional environmental review, and potential easements, with an estimated construction cost of approximately $1.15 million. Option 2 extends a transmission main that currently terminates at the end of Calle Joaquin using open-cut construction to create an alternate routing; this option has greater surface impacts, requires multiple easements, and an environmental review, with an estimated construction cost of about $2.3 million. Option 3 routes the waterline within the bridge structure in a steel casing, leveraging bridge construction but introducing added complexity and long-term maintenance considerations, at an estimated construction cost of
D218721CA.00 • June 2026 • City of San Luis Obispo
US101 and Prado Road Interchange • 6
approximately $1.19 million. Option 4 extends existing casing along the existing Prado Road alignment beneath the MSE Island wall, representing the simplest and most cost-effective solution at construction cost of roughly $75,000, but relying on the existing pipeline and casing being in acceptable condition.
Consor recommends Option 4 (Extending casing through the MSE Island wall) as the preferred approach, contingent on verification that the existing pipeline and casing are in good condition. This option provides the most cost-effective and least disruptive solution within the current project scope while meeting the objective of providing a maintainable east-west water system connection. The City may consider implementing one of the higher-cost alternatives in the future to enhance system redundancy and east– west connectivity. Full water-line alternatives memorandum is attached.
Utility Relocations/Undergrounding
The City desires to underground the overhead utilities along the Prado Road corridor as part of the interchange project. The Consor team has been working with PG&E, AT&T, Charter, and Astound to establish undergrounding plans. In general, the utilities located within the Prado Road corridor do not have prior rights and would be required to relocate their overhead facilities outside of the project limits at their own cost. The undergrounding of the utilities is above and beyond the costs outline in Franchise and Encroachment agreements. In general, the utilities determine the cost to underground their facilities and then provide the City with credit for the cost of relocating and staying overhead. At this time, we are working closely with PG&E to determine the cost of undergrounding their facilities as this will be the largest of the overhead utilities.
During our Utility outreach, it was determined that Phillips 66 has two 8-inch oil lines within a Joint Use Agreement (JUA) with Caltrans. This JUA dates to before US 101 was constructed and therefore, Phillips 66 has prior rights and will require reimbursement for the relocation of their facilities. The Consor team met with Phillips 66 and reviewed the proposed alignment for the northbound off-ramp, and the oil lines are in conflict and will need to be relocated as part of this project. The cost of the relocation is not known currently.
Caltrans Revisions to Ramp Terminal Intersection
The design team has been working closely with Caltrans to address their concerns with the two-lane overcrossing, the geometric layout of the northbound ramp intersection, and the hydraulic impacts to the structure, particularly scouring at the MSE island.
In conjunction with our traffic consultants, DKS, we have satisfied Caltrans Traffic Operations that the twolane overcrossing and northbound ramps will operate at an acceptable level. There was a concern that reducing the Prado Road overcrossing from 4-lanes to 2-lanes would have an adverse effect on the adjacent Madonna and Los Osos Valley Road (LOVR) interchanges. DKS prepared a comparison of future traffic volumes for all three interchanges and determined that the 2-lane overcrossing had a minor to no impact on the operations of the Madonna and LOVR interchanges in the design year of 2050 based on full general plan build out.
The northbound ramp intersection will require the widening of the Prado Road west overcrossing to accommodate sight distance and trucks turning east and west from the northbound off-ramp onto Prado Road. The bridge structure will be flared from a width of 65'-4" to 89'-10" on the west side of the ramp intersection. See Figure 2 below for the reconfiguration of the ramp intersection.
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US101 and Prado Road Interchange • 7
Figure 2: Revised/Widen Northbound Ramp Intersection
Caltrans issued a Structure Technical Policy (STP 2.6) for hydraulic design of structures over waterways in December 2025. STP 2.6 requires that structures over waterways be designed to withstand a scour event based on a 200-year flood. The Consor team requested a variance from this requirement on the basis that our structure is in a floodplain and does not span a creek or river. Unfortunately, Caltrans Structures Headquarters Hydraulics did not grant this variance. They agreed that the footing for the abutments within the MSE island do not need to be placed at the elevation of the depth of scour.
The revisions to the structures to accommodate the widening of the northbound ramp intersection and STP 2.6 has resulted in an increase to the project of approximately $2.5 million.
Conclusion
The goal of the Value Analysis Revalidation phase of the project was to incorporate VA recommendations from the PA&ED phase and continue to look for cost savings in the project design elements. The US 101 and Prado Road Interchange project is a necessary transportation improvement project for the improvement of local circulation, the improvement the pedestrian and bicycle connectivity, and the continued growth of the City of San Luis Obispo; however, the project needs to be cost effective and affordable. The reduction of the overcrossing to two travel lanes, the reconfiguration of the multi-modal facilities, the reduction of length of bridge structure, and the lowering of the vertical profile have resulted in cost reductions. The design team continues to keep construction costs at the forefront of our minds. The project is still in the early stages of design and there are cost impacts that are not known at this point, in particular the cost to underground utilities, relocation costs for the Phillips 66 oil lines, and obtaining the necessary right of way. As these costs become known, they will be shared with City staff. Below are construction costs for the roadway, structures, and wet utility relocations. The structure costs do include an allowance for aesthetic treatments The costs below include a 25% contingency and are based on 2026 dollars.
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US101 and Prado Road Interchange • 8
Current Construction Costs
(2026 dollars)
Roadway (incls signals and
lighting)
$19,700,000
Bridge $49,000,000
Retaining Walls $32,000,000
Water and Sewer Utility
Relocation
$3,000,000
Total $103,700,000
Attachments:
1. Performance Ranking Matrix
2. Supplemental Traffic Operations Memorandum
3. Existing Stormwater Map
4. Proposed Stormwater Control Measures
5. Proposed Drainage Improvements
6. Proposed Water and Sewer Relocations
7. Water line relocation cost analysis memorandum
ALTERNATIVES SCORING MATRIX
ALTERNATIVE RATING
SCORE
CRITERION PERFORM
SCORE
ALTERNATIVE RATING
SCORE
CRITERION PERFORM
SCORE
ALTERNATIVE RATING
SCORE
CRITERION PERFORM
SCORE
ALTERNATIVE RATING
SCORE
CRITERION PERFORM
SCORE
ALTERNATIVE RATING
SCORE
CRITERION PERFORM
SCORE
No back up on NB US 101 Mainline 15.5% 5 77 5 77 5 77 5 77 5 77 Bike and Pedestrian Level of Stress 11.6% 3 35 3 35 4 46 5 58 2 23 Crash Severity on Prado, Mainline Ramp merge and diverge 14.2% 2 28 3 43 5 71 4 57 2 28 Driver queuing during peak hours 7.7% 5 39 3 23 4 31 4 31 5 39 Delay Peak Hour 7.1% 5 35 3 21 4 28 4 28 5 35
Emergency Response Vehicles 11.6% 5 58 3 35 4 46 4 46 5 58 Level of Service 5.2% 5 26 3 15 4 21 4 21 5 26
Safety queuing issues 11.6% 5 58 3 35 4 46 4 46 5 58
Accommodate Future Land Uses - additional land use 3.2% 5 16 4 13 3 10 3 10 5 16 Low Target Speed 7.7% 2 15 4 31 5 39 5 39 2 15
Maintenance/Future Life Cycle Costs 3.2% 3 10 3 10 4 13 4 13 3 10 Goods movement at Prado and Elks Intersection 0.6% 4 3 4 3 4 3 4 3 4 3 Delay Non- Peak 0.6% 4 3 4 3 5 3 5 3 4 3
0 0.0% 0 0 0 0 00 0.0% 0 0 0 0 00 0.0% 0 0 0 0 00 0.0% 0 0 0 0 00 0.0% 0 0 0 0 00 0.0% 0 0 0 0 00 0.0% 0 0 0 0 00 0.0% 0 0 0 0 0 403 343 435 432 392
Apply following rating scale to each criterion for each Alternative:
5 - Excellent4 - Good3 - Fair2 - Poor1 - Very Poor
PERFORMANCE SCORING SUMMARYALTERNATIVES COST SUMMARY
Bridge and Roadway Costs Only - Present Day Values30% Contingency, No Utility Costs, No ROW Costs VALUE = PERFORMANCE / $
#DIV/0!
Four Lane Signalized - Class IV both sides
5.1 5.0 5.1 5.1 4.3
ALTERNATIVE 6
$79,300,000 $69,100,000 $85,575,000 $84,800,000 $90,425,000 ALTERNATIVE 1 ALTERNATIVE 2 ALTERNATIVE 3 ALTERNATIVE 4 ALTERNATIVE 5ALTERNATIVE 1 ALTERNATIVE 2 ALTERNATIVE 3 ALTERNATIVE 4 ALTERNATIVE 5 ALTERNATIVE 6 0 ALTERNATIVE 5 ALTERNATIVE 6
392
Two Lane Signalized - Class I with S/W Roundabout Corridor with Yield Roundabout at Ramp/Signal at Elks 403
ALTERNATIVE 2
343
ALTERNATIVE 3 ALTERNATIVE 4
435 432
ALTERNATIVE 1
EVALUATION CATEGORY / CRITERION PERFORM CRITERION WEIGHT Four Lane Signalized - Class I with S/W
GAD TRAFFIC ANALYSIS
DATE: May 15, 2026
TO: Brent Lemon, PE | Consor
Dace Morgan, PE | Consor
FROM: Jim Damkowitch | DKS
Joel Rabinovitz, PE | DKS
SUBJECT: 05-1H640 US101 and Prado Road Interchange -- Supplemental Project Report
Project #24989-000
INTRODUCTION
The following traffic analysis was completed to support the US101 and Prado Road Interchange project. The relative performance of various design elements of the proposed project were analyzed under AM/PM peak hour 2050 future year conditions and compared across the following three performance metrics:
• Vehicular Level of Service (based on Highway Capacity Manual 7th Edition – HCM 7 grades using static and simulation delay results)
• Vehicular Delay (using both static and simulation modeling) • Vehicular 95th Percentile Queue (based on simulation modeling) The peak hour volume sets used for these operational determinations were based on the most recent travel demand modeling developed by the City of San Luis Obispo. All demand profiles reflect future mode shifts to transit. Pursuant to NCHRP Report 765 Analytical Travel Forecasting Approaches for Project-Level Planning and Design, 2014, travel demand model outputs were post-processed using traffic counts collected in May 2025. The traffic counts include pedestrians and bicyclists. For the Future Year (2050) Build condition these pedestrian/bicycle counts were manually adjusted to reflect the anticipated increase in pedestrian/bicycle activity to result from the project (i.e., overcrossing connectivity and planned bicycle and pedestrian facilities in the proposed project).
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 2
STUDY AREA
The focus of the analysis is on Prado Road at the following two intersections:
1. Prado Road / US 101 NB Ramps
2. Prado Road / Elks Lane
Currently Elks Lane and the US 101 NB ramps intersect at an all-way-stop. With the extension of Prado Road to Froom Ranch Way (Figure 1), Elks Lane would be realigned with the City's new Water Resource Recovery Facility (WRRF) and Corporation Yard entrance.
FIGURE 1: STUDY AREA
Prado Road Extension Elks Lane Realignment
1 2
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 3
VALUE ENGINEERING PROCESS
A value engineering (VE) process is a structured, multidisciplinary review used to confirm that a project provides the needed functions safely, reliably, and efficiently while improving value and managing cost. For the Prado Road interchange, the process included reviewing the previously identified need for a four-lane Prado Road cross-section over US 101, defining the essential project functions, identifying design constraints and opportunities, developing and screening potential design refinements, and comparing alternatives based on operations, safety, constructability, right-of-way, environmental effects, cost, and long-term performance.
During the VE process, the team looked at a 4-lane and 2-lane overcrossing, different placement of pedestrian and bicycle facilities, different control types (signal and roundabout), right-of-way impacts, and cost. The GAD Design (2-Lane Overcrossing) is the culmination of the VE process.
GAD DESIGN (2-LANE OVERCROSSING)
From the VE design process, the preferred Build design (GAD Design 2-Lane Overcrossing) shown in Figure 2 includes a two-lane overcrossing over US 101, four lanes extending from east of the US 101 NB ramps to Higuera Street, shoulder and sidewalk on the north side of Prado Road, and a shoulder and two-way mixed-use path (MUP) on the south side. This alternative includes signals at the US 101 NB ramps and Elks Lane intersections, with the westbound right-turn at the US 101 NB ramps intersection controlled by the signal as well. With the bi-directional MUP on the south side of Prado Road, the northbound right turns onto Prado Road were assumed to operate as no right-turn on red (RTOR). The US 101 northbound on-ramp would be a single lane and add an auxiliary lane to US 101 between the Prado Road and Madonna Road interchanges, resulting in a weave condition.
The addition of the auxiliary lane was approved by City Council on November 4, 2025.
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 4 FIGURE 2: GAD DESIGN (2-LANE OVERCROSSING)
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 5
ANALYSIS METHODOLOGY
The methodologies used for the purpose of analyzing the various design elements of the proposed project alternatives are described below. Two forms of analysis were applied: static and stochastic.
The static analysis is primarily based on methods described in the Highway Capacity Manual (HCM).
Static analysis uses a fixed data input set along with a set of equations to develop a deterministic result versus stochastic analysis which uses a set of inputs with multi-run variance to derive a set of measured rather than calculated results (i.e., microsimulation). The SYNCHRO modeling software was applied for static analyses while the VISSIM modeling software was applied for stochastic operational determinations. Freeway analysis was performed using the Leisch method, which is also a static analysis.
HIGHWAY CAPACITY MANUAL ANALYSIS
The operation or performance of roadway facilities is commonly described in terms of Level of Service (LOS). LOS is a qualitative measure of effectiveness describing traffic operations based on such factors as speed, travel time, delay, and freedom to change lanes for all vehicles. Six levels are defined from LOS A, as the best-operating conditions, to LOS F, or the worst operating conditions.
LOS E represents “at-capacity” operations. Study intersections were analyzed to determine their LOS based on the definitions and formulas presented in the Highway Capacity Manual 7th Edition (HCM 7) as implemented by the SYNCHRO analysis software. Table 1 presents the LOS criteria for intersections in accordance with the HCM 7 methodology.
TABLE 1: INTERSECTION LEVEL OF SERVICE CRITERIA - SIGNAL
LEVEL OF SERVICE (LOS) TOTAL DELAY PER VEHICLE
(SECONDS) A
A < 10
B > 10 and < 20
C > 20 and < 35
D > 35 and < 55
E > 55 and < 80
F > 80
Notes:
A. HCM 7, Chapter 19 (Signalized Intersections)
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 6
MICROSIMULATION ANALYSIS
Microsimulation analysis was conducted using the VISSIM modeling software to better reflect the effects of the close intersection spacing as well as lane utilization that the HCM methodologies do not specifically address. The models were developed, and analysis was conducted in accordance with the FHWA guidelines for microsimulation analysis1.
It should be noted that the VISSIM models used for this analysis were not calibrated to existing conditions. However, the Existing configuration (no overcrossing, all-way stop) and future configuration (with overcrossing, signal or roundabout) are different enough that much of the calibration for the Existing condition (e.g., how drivers yield at the stop sign) would not be useful for the Future Build conditions. The driver behavior and other model parameters were based on previous models developed by DKS for similar facilities. Delay results from the microsimulation analysis are compared to HCM LOS criteria for intersections for the purpose of consistency with other analysis in this report.
QUEUING
95th percentile queue results are defined as the length of the queue which is exceeded five percent of the time during the analysis time period. The 95th percentile queue is useful in determining the appropriate storage requirements such as length of turn pockets but is not representative of what an average driver would experience during their commute.
SYNCHRO was used to identify the average and 95th percentile vehicle queues for approaching traffic for the future peak volumes. The 95th percentile queue in SYNCHRO is a calculation of the maximum back of queue with 95th percentile traffic volume, and not an actual observed queue.
VISSIM was also used to estimate the average and 95th percentile vehicle queues for approaching traffic for each study intersection for the one-hour system peak hour. To calculate 95th percentile queues, queue length data was collected from VISSIM using queue counters on critical approaches with a 120-second interval to reflect queues that form while traffic flow is impeded. The average and 95th percentile queue was then calculated using a percentile function in Excel.
DKS considers micro-simulation as a superior approach for queuing analysis given its ability to more accurately reflect the operational interaction of adjacent intersections, in particular, closely spaced intersections. It is also better at reflecting the interactions of pedestrians and bicyclists at intersections of all control types.
1 Traffic Analysis Toolbox Volume III: Guidelines for Applying Traffic Microsimulation Modeling Software. Federal Highway Administration (FHWA). August 2003.
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 7
CONGESTION
The simulation model was also used to measure motor vehicle delay relative to desired speed as an indicator of congestion. The delay is measured as a percentage of travel time for a given roadway segment. The colors shown indicate the following approximate queue states:
• Dark Green = Free flow, no delay (delay less than 5 percent of travel time) • Light green = Slight slowing (5-20 percent)
• Yellow = Increased slowing, but not yet stop and go (20-40 percent) • Orange = Furthest extend of stop and go queues, rough approximation of 95th percentile queue (40-60 percentile)
• Red = Fluctuates between low-speed flow and stopped queue (60-80 percentile) • Dark Red = Stop and go queue during the entire 15-minutes peak interval (delay greater than 80 percentile of travel time)
FUTURE FORECASTS
The peak hour volume sets used for these operational determinations were based on the most recent travel demand modeling developed by the City of San Luis Obispo. All demand profiles reflect future mode shifts to transit. Pursuant to NCHRP Report 765, travel demand model outputs were postprocessed using traffic counts collected in May 2025. The traffic counts include pedestrians and bicyclists. For the Future Year Build condition these ped/bike counts were manually adjusted to reflect the anticipated increase in pedestrian/bicycle activity to result from the project (i.e., overcrossing connectivity and planned bicycle and pedestrian facilities in the proposed project).
Additionally, future forecasts included the completion of the Prado Creek Bridge project and related Higuera Street / Prado Road intersection improvements, as well as the planned extension of Prado Road east to Broad Street.
Future (Year 2050) forecasts for the AM and PM peak hours for the 2-lane overcrossing are shown in Figure 3.
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 8 FIGURE 3: FUTURE (YEAR 2050) INTERSECTION VOLUMES – 2-LANE OVERCROSSING
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 9
VOLUME COMPARISON
To ensure consistency with the prior Traffic Operations Analysis Report (TOAR) completed in 2019, and the updated TOAR completed in 2023, the volume forecasts at Madonna Road, Prado Road, and Los Osos Valley Road were compared between the prior reports and the forecasting completed for this study. The 2023 report utilized the same base data as the 2019 report and applied a 5% growth factor to the forecasts to represent an adjusted forecast year of 2045 compared to the 2040 forecast used in the original TOAR. For the 2019 TOAR and 2023 TOAR update, traffic counts from 2014 were used to establish existing conditions. Table 2 summarizes the following data:
• The 2014 counts from the TOAR
• The 2025 counts collected for this study
• The 2025 forecast from the TOAR Update
• The 2045 No Project (i.e., no Prado Road OC) forecast from the TOAR update • The 2050 No Project forecast prepared by this study
• The 2045 Project (i.e., 4-lane Prado Road OC) forecast from the TOAR update • The 2050 Project (i.e., 4-lane and 2-lane Prado Road OC) forecasts prepared by this study Several data trends can be discerned from this data comparison. First, the 2025 Count data collected generally aligns with the previously forecasted 2025 data during both the AM and PM peak periods.
Second, the updated 2050 No Project forecasts are lower in most cases than the previous 2045 forecasts. This is generally due to changes in the City General Plan land use data used in the newer forecasts. This same trend continues in the Project forecast volumes, except at the Prado Road interchange, where the updated forecasts are higher than those shown in the 2023 TOAR forecast.
Finally, when comparing the 4-lane overcrossing project forecasts with the 2-lane overcrossing project forecasts, the table shows that most travel demands shift by 10% or less. The net result of this data comparison shows that results from this VE study are in alignment with the adopted TOAR.
If re-evaluation of facilities beyond the Prado Road interchange were to be conducted, they would show similar or improved operational performance when compared with the adopted TOAR. The data also shows that changes in City planning has resulted in lower potential vehicle demand growth at the subject interchanges over time when compared with prior studies.
VEHICLE MILES TRAVELLED (VMT) IMPLICATIONS
The findings of volume comparison suggest a neutral effect on VMT. The close alignment between the updated travel forecasts with the adopted TOAR combined with the lower or de-minimis volume differences between the 4-lane and the 2-lane cross section supports this finding. To repeat, if reevaluation of facilities beyond the Prado Road interchange were to be conducted, they would show similar or improved operational performance (i.e., lower future volumes and therefore lower VMT) when compared with the adopted TOAR. Recently revised land use projections by the City have resulted in lower potential vehicle demand growth (i.e., VMT) within the US 101/Prado Interchange study area when compared with prior studies including the adopted TOAR.
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 10 TABLE 2: FORECASTING COMPARISON TABLE BETWEEN 2023 TOAR AND 2026 VE DOCUMENTS ROAD FROM TO 2014 COUNT 2025
COUNT
TOAR
UPDATE
2025
FORECAST
TOAR
UPDATE
2045 NO
PROJECT
FORECAST
VE 2050
NO
PROJECT
FORECAST
CHANGE IN
NO
PROJECT
FORECASTS
TOAR
UPDATE
2045
PROJECT
FORECAST
VE 2050
4-LANE OC
PROJECT
FORECAST
CHANGE IN
4-LANE OC
PROJECT
FORECASTS
VE 2050
2-LANE OC
PROJECT
FORECAST
CHANGE IN
FORECASTS
FROM 4-
LANE TO 2-
LANE OC
MADONNA RD Higuera St US-101 NB Ramps 547 (920) 638 (1168) 761 (1232) 1046 (1437) 625 (1470) -421(33) 840 (901) 525 (1060) -315 (159) 470 (1115) -55 (55) MADONNA RD US-101 NB Ramps US-101 SB Ramps 554 (930) 642 (1115) 768 (1201) 1050 (1342) 755 (1325) -295(-17) 721 (805) 315 (780) -406 (-25) 290 (880) -25 (100) MADONNA RD US-101 SB Ramps El Mercado St 715 (1339) 800 (1569) 936 (1602) 1264 (1801) 1000 (1765) -264(-36) 1052 (1296) 570 (1210) -482 (-86) 540 (1290) -30 (80) MADONNA RD El Mercado St US-101 SB Ramps 1180 (1366) 1270 (1385) 1294 (1491) 1381 (1668) 1500 (1535) 119(-133) 1082 (1486) 945 (1320) -137 (-166) 1050 (1280) 105 (-40) MADONNA RD US-101 SB Ramps US-101 NB Ramps 1601 (1424) 1662 (1491) 1694 (1575) 2064 (1802) 1895 (1635) -169(-167) 1623 (1597) 1325 (1400) -298 (-197) 1430 (1360) 105 (-40) MADONNA RD US-101 NB Ramps Higuera St 1215 (992) 1167 (1019) 1318 (1061) 1691 (1240) 1350 (1040) -341(-200) 1250 (992) 880 (795) -370 (-197) 930 (785) 50 (-10) US-101 NB OFF-RAMP US-101 NB Madonna Rd 266 (299) 290 (323) 278 (273) 290 (254) 350 (235) 60(-19) 290 (182) 140 (125) -150 (-57) 155 (160) 15 (35) US-101 NB ON-RAMP Madonna Rd US-101 NB 649 (721) 781 (852) 647 (818) 659 (911) 795 (965) 136(54) 784 (936) 710 (975) -74 (39) 755 (945) 45 (-30) US-101 SB OFF-RAMP US-101 SB Madonna Rd 782 (857) 793 (917) 861 (894) 1238 (1052) 890 (905) -348(-147) 1238 (1053) 880 (885) -358 (-168) 880 (880) 0 (-5) US-101 SB ON-RAMP Madonna Rd US-101 SB 144 (377) 229 (379) 232 (409) 289 (476) 240 (385) -49(-91) 289 (477) 240 (395) -49 (-82) 240 (400) 0 (5) PRADO RD Higuera St US-101 NB Ramps 244 (492) 327 (696) 320 (546) 378 (641) 585 (995) 207(354) 1063 (1841) 995 (2020) -68 (179) 990 (1790) -5 (-230) PRADO RD US-101 NB Ramps Froom Ranch Way 801 (1345) 860 (1260) 59 (-85) 810 (1050) -50 (-110) PRADO RD Froom Ranch Way US-101 NB Ramps 956 (821) 1320 (620) 364 (-201) 1055 (665) -265 (45) PRADO RD US-101 NB Ramps Higuera St 224 (139) 258 (133) 310 (149) 425 (147) 350 (145) -75(-2) 1231 (816) 1425 (740) 194 (-76) 1250 (745) -175 (5) US-101 NB OFF-RAMP US-101 NB Prado Rd 225 (135) 235 (100) 311 (145) 452 (179) 360 (130) -92(-49) 489 (213) 505 (295) 16 (82) 475 (255) -30 (-40) US-101 NB ON-RAMP Prado Rd US-101 NB 250 (495) 324 (695) 326 (541) 399 (646) 595 (1005) 196(359) 470 (709) 520 (975) 50 (266) 450 (935) -70 (-40) LOS OSOS VALLEY RD Higuera St US-101 NB Ramps 463 (923) 546 (1032) 658 (1132) 769 (1717) 545 (1480) -224(-237) 533 (1472) 335 (950) -198 (-522) 350 (1125) 15 (175) LOS OSOS VALLEY RD US-101 NB Ramps US-101 SB Ramps 753 (1229) 901 (1333) 969 (1454) 1181 (2059) 865 (1745) -316(-314) 928 (1709) 630 (1195) -298 (-514) 650 (1335) 20 (140) LOS OSOS VALLEY RD US-101 SB Ramps Calle Joaquin 919 (1521) 1146 (1705) 1110 (1692) 1328 (2350) 1055 (1890) -273(-460) 1168 (1999) 830 (1415) -338 (-584) 845 (1530) 15 (115) LOS OSOS VALLEY RD Calle Joaquin US-101 SB Ramps 909 (1485) 1109 (1555) 1105 (1583) 1642 (2229) 1430 (1535) -212(-694) 1161 (2002) 865 (1360) -296 (-642) 960 (1345) 95 (-15) LOS OSOS VALLEY RD US-101 SB Ramps US-101 NB Ramps 1007 (1029) 1151 (1207) 1227 (1089) 1763 (1622) 1750 (1350) -13(-272) 1190 (1394) 1190 (1140) 0 (-254) 1290 (1125) 100 (-15) LOS OSOS VALLEY RD US-101 NB Ramps Higuera St 1048 (829) 1118 (941) 1332 (885) 1876 (1357) 1735 (1050) -141(-307) 1303 (1234) 1175 (845) -128 (-389) 1275 (830) 100 (-15) US-101 NB OFF-RAMP US-101 NB Los Osos Valley Rd 546 (579) 588 (549) 643 (620) 822 (668) 555 (535) -267(-133) 804 (668) 530 (510) -274 (-158) 530 (510) 0 (0) US-101 NB ON-RAMP Los Osos Valley Rd US-101 NB 215 (467) 251 (514) 227 (502) 296 (591) 235 (570) -61(-21) 296 (591) 230 (555) -66 (-36) 230 (595) 0 (40) US-101 SB OFF-RAMP US-101 SB Los Osos Valley Rd 621 (611) 693 (720) 676 (573) 857 (638) 920 (740) 63(102) 857 (637) 925 (730) 68 (93) 925 (730) 0 (0) US-101 SB ON-RAMP Los Osos Valley Rd US-101 SB 363 (773) 406 (693) 413 (829) 588 (953) 405 (785) -183(-168) 588 (954) 400 (735) -188 (-219) 400 (755) 0 (20) Note: Reported numbers are AM (PM) peak hours
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 11 FREEWAY ANALYSIS – LEISCH METHOD
The Leisch method is a freeway weaving analysis procedure developed by Jack E. Leisch for evaluating the operational performance of freeway segments where entering and exiting traffic streams must cross paths over a limited distance, such as between successive on- and off-ramps, and evaluating whether the available weaving length, number of lanes, traffic volumes, and distribution of weaving and non-weaving movements can accommodate the expected demand. In a freeway analysis, forecast or observed traffic volumes are assigned to each movement through the weaving section, then compared against the operating thresholds or service-volume relationships established by the Leisch procedure to estimate whether the segment is likely to operate acceptably or experience speed reductions, turbulence, or congestion. The results are used as a planning-level screening tool to flag ramp-spacing or lane-changing constraints and to determine whether improvements such as auxiliary lanes, revised ramp configurations, increased weaving distance, or more detailed operational analysis may be needed. For purposes of this analysis, the Leisch method will be performed using Excel-based tools to evaluate freeway weaving operations based on traffic volumes, lane configurations, and weaving-section geometry.
The Leisch method determines the LOS of the overall weaving section by comparing the calculated service volume (SV), expressed in passenger cars per hour per lane (pcphpl), to the allowable service-volume thresholds for the number of basic freeway lanes (Nb). In practice, the analysis first converts demand volumes to passenger-car flow rates, identifies the applicable weaving configuration, and uses the Leisch nomograph or Excel implementation to determine the resulting SV for the section. That SV is then compared to the LOS thresholds shown in Table 3. The Leisch procedure also recognizes that weaving and non-weaving traffic may operate at different levels of service; in those cases, supplemental speed calibration is used to reconcile the overall section LOS with the weaving-movement LOS.
TABLE 3: LEISCH METHOD LOS
LEVEL OF SERVICE (LOS)
MAXIMUM SERVICE VOLUME (PCPHPL)
NB = 2 NB = 3 NB = 4
A 750 800 850
B 1000 1100 1200
C 1250 1350 1450
D 1550 1600 1650
E 1900 1900 1900
F >1900 >1900 >1900
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 12
OPERATIONAL ANALYSIS RESULTS
The following section describes the intersection and freeway operations for Future Year (2050). The delay, LOS and queue results for SYNCHRO (Section 1) and VISSIM () as well as the Leisch method graph results () can be found in the Appendix.
LEVEL OF SERVICE (LOS)
The analysis results for the intersection performance for the Future Year (2050) AM and PM peak hours are provided in Table 4. As shown, under No Build conditions, the Prado Road / US 101 NB / Elks Lane intersection is projected to operate at LOS F during the PM peak hour with significant delay (> 2 minutes). Under Build (GAD Design 2-Lane Overcrossing) conditions, all intersections under both time periods would operate at LOS C or better.
When comparing results from SYNCHRO and VISSIM (microsimulation), they are generally similar between time periods, showing that even though the VISSIM models were not calibrated to existing conditions, the assumptions made for driver behavior are consistent with the output from SYNCHRO.
TABLE 4: NO-BUILD FUTURE YEAR (2050) INTERSECTION PERFORMANCE – DELAY AND LOS Note:
A. Average delay in seconds per vehicle. Bold indicates the LOS exceeds the City’s mobility standard.
B. SYNCHRO is a deterministic model and VISSIM a microsimulation model. While the results may be similar, SYNCHRO does not consider downstream queue spillback, while VISSIM does.
C. The Prado Rd / Elks Ln intersection does not exist in the No Build. Elks Ln intersects Prado Rd at the NB off-ramp.
QUEING ANALYSIS
The Future (2050) average and 95th percentile queue lengths for each intersection for the AM and PM peak hours are presented in Table 5 through Table 8. Also shown are queue lengths from SYNCHRO and VISSIM, with VISSIM queues generally longer than queues from SYNCHRO. It should be noted (and described above), the SYNCHRO queue lengths are calculated using equations while VISSIM queue lengths are calculated from observed queue lengths. However, the results between SYNCHRO and VISSIM are consistent in identifying movements that could experience queues in the future. The following discussion is based on the results of the VISSIM analysis.
INTERSECTION SOFTWARE B
DELAY A (LOS)
NO BUILD C
GAD DESIGN (2-LANE OC)
AM PEAK PM PEAK
AM PEAK PM PEAK DELAY LOS DELAY LOS
PRADO RD / US
101 NB RAMPS
SYNCHRO 23 (C) 130 (F) 17 B 19 B
VISSIM 19 (C) 202 (F) 20 C 19 B
PRADO RD /
ELKS LN
SYNCHRO - - 16 B 21 C
VISSIM - - 14 B 26 C
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 13
AVERAGE QUEUE LENGTH
As shown in the tables, average queue lengths (i.e., the queue experienced on average by a driver) are expected to be contained within the available storage and do not extend back to upstream intersections, except for the following:
No Build
• Westbound at Prado Road / US 101 NB Ramps (PM peak)
While the No Build westbound average queue does not extend to Higuera Street during the PM peak, it is within 100 feet of the intersection, meaning that at any given time during the PM peak queues are expected to extend from the US 101 NB ramps back to nearly Higuera Street. This is consistent with the high delay for this movement shown in Table 4. 95TH PERCENTILE QUEUE LENGTH
As shown in the tables, several 95th percentile queue lengths are expected to exceed available storage or extend back to upstream intersections during both the AM and PM peak hours, as described below:
No Build
• Westbound at Prado Road / US 101 NB Ramps (PM peak)
During the PM peak, under No Build conditions, westbound queues are projected to extend back beyond Higuera Street.
GAD Design
• Northbound right at Prado Road / US 101 NB Ramps (AM peak) • Westbound right at Prado Road / US 101 NB Ramps (PM peak) • Westbound through at Prado Road / US 101 NB Ramps (PM peak) • Westbound through at Prado Road / Elks Lane (PM peak) During the AM peak hour the northbound right-turn queue would exceed available storage (330 feet) but does not result in queues back onto the US 101 NB mainline. It should be noted that the 95th percentile queue of 345 feet is less than one vehicle beyond the available storage, and would likely only queue into the taper
The heavy westbound demand (1,600 to 1,700) during the PM peak hour results in westbound queues extending back from the US 101 NB Ramps (both in the right and through lanes) intersection to the Elks Lane intersection, and then back to the Higuera Street intersection.
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 14 TABLE 5: FUTURE (2050) AM PEAK HOUR QUEUE LENGTHS – AVERAGE Note:
All queues are rounded to nearest 5’.
A. L = Left. T = Thru. R = Right.
B. SYNCHRO does not calculate the average queue for all-way stop intersections.
ALTERNATIVE SOFTWARE
QUEUE LENGTH (FT) A
EASTBOUND WESTBOUND NORTHBOUND SOUTHBOUND
L T R L T R L T R L T R
PRADO RD / US 101 NB RAMPS
NO BUILD
(NO OC)
SYNCHRO B - - - - -
VISSIM - - 225 40 20
GAD DESIGN
(2-LANE OC)
SYNCHRO 45 340 - - 150 0 95 130 - - -
VISSIM 75 390 - - 160 135 125 175 - - -
PRADO RD / ELKS LN
GAD DESIGN
(2-LANE OC)
SYNCHRO 10 75 5 40 5 5 10 5
VISSIM 30 185 20 150 10 10 35 25
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 15 TABLE 6: FUTURE (2050) AM PEAK HOUR QUEUE LENGTHS – 95TH PERCENTILE Note:
All queues are rounded to nearest 5’. BOLD indicates the queue exceeds the storage length or extends back to the next upstream intersection.
A. L = Left. T = Thru. R = Right.
B. # = 95th percentile volume exceeds capacity, queue may be longer.
ALTERNATIVE SOFTWARE
QUEUE LENGTH (FT) A
EASTBOUND WESTBOUND NORTHBOUND SOUTHBOUND
L T R L T R L T R L T R
PRADO RD / US 101 NB RAMPS
NO BUILD
(NO OC)
SYNCHRO - - 235 70 10
VISSIM - - 475 120 60
GAD DESIGN
(2-LANE OC)
SYNCHRO 95 545 - - 260 50 190 #280 B - - -
VISSIM 155 855 - - 380 375 240 345 - - -
PRADO RD / ELKS LN
GAD DESIGN
(2-LANE OC)
SYNCHRO 55 355 35 195 25 25 55 50
VISSIM 70 325 60 310 45 40 85 75
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 16 TABLE 7: FUTURE (2050) PM PEAK HOUR QUEUE LENGTHS – AVERAGE Note:
All queues are rounded to nearest 5’. BOLD indicates the queue exceeds the storage length or extends back to the next upstream intersection.
A. L = Left. T = Thru. R = Right.
B. SYNCHRO does not calculate the average queue for all-way stop intersections.
ALTERNATIVE SOFTWARE
QUEUE LENGTH (FT) A
EASTBOUND WESTBOUND NORTHBOUND SOUTHBOUND
L T R L T R L T R L T R
PRADO RD / US 101 NB RAMPS
NO BUILD
(NO OC)
SYNCHRO B - - - - -
VISSIM - - 1545 10 20
GAD DESIGN
(2-LANE OC)
SYNCHRO 55 120 - - 445 45 100 85 - - -
VISSIM 65 135 - - 455 455 100 85 - - -
PRADO RD / ELKS LN
GAD DESIGN
(2-LANE OC)
SYNCHRO 35 85 5 445 20 25 35 5
VISSIM 45 105 10 545 25 30 40 35
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 17 TABLE 8: FUTURE (2050) PM PEAK HOUR QUEUE LENGTHS – 95TH PERCENTILE Note:
All queues are rounded to nearest 5’. BOLD indicates the queue exceeds the storage length or extends back to the next upstream intersection.
A . L = Left. T = Thru. R = Right.
B. # = 95th percentile volume exceeds capacity, queue may be longer.
ALTERNATIVE SOFTWARE
QUEUE LENGTH (FT) A
EASTBOUND WESTBOUND NORTHBOUND SOUTHBOUND
L T R L T R L T R L T R
PRADO RD / US 101 NB RAMPS
NO BUILD
(NO OC)
SYNCHRO - - 950 20 10
VISSIM - - 1690 60 60
GAD DESIGN
(2-LANE OC)
SYNCHRO 115 225 - - #870 B 240 180 155 - - -
VISSIM 135 320 - - 740 735 200 180 - - -
PRADO RD / ELKS LN
GAD DESIGN
(2-LANE OC)
SYNCHRO 75 180 25 635 50 65 75 50
VISSIM 105 220 45 945 65 80 95 90
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 18
CONGESTION
Visual inspection of the congestion provides additional context for the Build scenario operations. As shown in Figure 4 (AM) and Figure 5 (PM), some localized congestion is expected on the US 101 northbound off-ramp during the AM peak and along Prado Road during the PM peak. However, the slowing and queuing remain generally contained within the study area and do not extend far enough to affect upstream facilities, including the freeway mainline or adjacent intersections. In contrast, the No Build PM condition (Figure 6) shows substantially more queuing, with congestion extending east from the US 101 northbound ramps along Prado Road to beyond Higuera Street. This comparison indicates that the Build scenario would reduce the extent and severity of queuing relative to the No Build condition.
FIGURE 4: GAD DESIGN (2-LANE OVERCROSSING) AM CONGESTION
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 19 FIGURE 5: GAD DESIGN (2-LANE OVERCROSSING) PM CONGESTION FIGURE 6: NO BUILD PM CONGESTION
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 20
FREEWAY ANALYSIS
The Leisch method results show that in Year 2050 the US 101 NB weave between Prado Road onramp and Madonna Road off-ramp would operate at LOS C in the AM peak and LOS D in the PM peak, showing that the proposed aux lane from Prado Road on-ramp to Madonna Road off-ramp would operate acceptably.
SUMMARY
Overall, the GAD Design (2-Lane Overcrossing) provides a clear operational benefit compared to the No Build condition by improving intersection operations, reducing delay, and better managing queues under future 2050 AM and PM peak hour conditions. The analysis shows that the Prado Road / US 101 northbound ramps / Elks Lane intersection in No Build is projected to operate at LOS F during the PM peak hour with significant delay greater than two minutes, while the Build (GAD Design 2- Lane Overcrossing) condition operates at LOS C or better at all study intersections in both peak periods.
The GAD Design (2-Lane Overcrossing) also provides benefits by containing congestion and reducing the extent of queuing relative to the No Build condition. While some localized queues are expected in the Build (GAD Design 2-Lane Overcrossing) scenario, including on the US 101 northbound offramp in the AM peak and along Prado Road in the PM peak, the congestion generally remains within the study area and does not extend far enough to affect upstream facilities such as the freeway mainline. By comparison, the No Build PM condition shows extensive queuing along Prado Road from the US 101 northbound ramps toward and beyond Higuera Street. This indicates that the GAD design (2-Lane Overcrossing) improves overall corridor operations, provides better queue management, and supports the planned Prado Road extension and multimodal connectivity improvements.
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026
APPENDIX
CONTENTS
Section 1: SYNCHRO Results
Section 2: VISSIM Results
Section 3: Leisch Method Results
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 SECTION 1: SYNCHRO RESULTS
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026
NO BUILD
AM PEAK HOUR
HCM 7th AWSC
3: US 101 NB Off/Elks Lane & Prado Rd 0_No Build AM
City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 1
Intersection
Intersection Delay, s/veh 22.8
Intersection LOS C
Movement EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR Lane Configurations
Traffic Vol, veh/h 0 0 0 0 565 15 0 30 310 55 0 15
Future Vol, veh/h 0 0 0 0 565 15 0 30 310 55 0 15
Peak Hour Factor 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Heavy Vehicles, % 2 2 2 4 10 10 4 5 5 20 4 20
Mvmt Flow 0 0 0 0 565 15 0 30 310 55 0 15
Number of Lanes 000010010101
Approach WB NB SB
Opposing Approach SB NB
Opposing Lanes 0 2 1
Conflicting Approach Left NB WB
Conflicting Lanes Left 1 0 1
Conflicting Approach Right SB WB
Conflicting Lanes Right 2 1 0
HCM Control Delay, s/veh 29.6 13.7 10.9
HCM LOS D B B
Lane NBLn1 WBLn1 SBLn1 SBLn2
Vol Left, % 0% 0% 100% 0%
Vol Thru, % 9% 97% 0% 0%
Vol Right, % 91% 3% 0% 100%
Sign Control Stop Stop Stop Stop
Traffic Vol by Lane 340 580 55 15
LT Vol 0 0 55 0
Through Vol 30 565 0 0
RT Vol 310 15 0 15
Lane Flow Rate 340 580 55 15
Geometry Grp 4a 2 5 5
Degree of Util (X) 0.503 0.841 0.115 0.026
Departure Headway (Hd) 5.323 5.219 7.546 6.32
Convergence, Y/N Yes Yes Yes Yes
Cap 677 696 474 565
Service Time 3.366 3.248 5.306 4.079
HCM Lane V/C Ratio 0.502 0.833 0.116 0.027
HCM Control Delay, s/veh 13.7 29.6 11.3 9.2
HCM Lane LOS B D B A
HCM 95th-tile Q 2.8 9.4 0.4 0.1
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026
NO BUILD
PM PEAK HOUR
HCM 7th AWSC
3: US 101 NB Off/Elks Lane & Prado Rd 0_No Build PM
City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 1
Intersection
Intersection Delay, s/veh 130.2
Intersection LOS F
Movement EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR Lane Configurations
Traffic Vol, veh/h 0 0 0 0 980 30 0 10 125 45 0 25
Future Vol, veh/h 0 0 0 0 980 30 0 10 125 45 0 25
Peak Hour Factor 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Heavy Vehicles, % 2 2 2 4 5 5 2 5 5 10 4 10
Mvmt Flow 0 0 0 0 980 30 0 10 125 45 0 25
Number of Lanes 000010010101
Approach WB NB SB
Opposing Approach SB NB
Opposing Lanes 0 2 1
Conflicting Approach Left NB WB
Conflicting Lanes Left 1 0 1
Conflicting Approach Right SB WB
Conflicting Lanes Right 2 1 0
HCM Control Delay, s/veh 154.4 10.9 11
HCM LOS F B B
Lane NBLn1 WBLn1 SBLn1 SBLn2
Vol Left, % 0% 0% 100% 0%
Vol Thru, % 7% 97% 0% 0%
Vol Right, % 93% 3% 0% 100%
Sign Control Stop Stop Stop Stop
Traffic Vol by Lane 135 1010 45 25
LT Vol 0 0 45 0
Through Vol 10 980 0 0
RT Vol 125 30 0 25
Lane Flow Rate 135 1010 45 25
Geometry Grp 4a 2 5 5
Degree of Util (X) 0.209 1.286 0.091 0.042
Departure Headway (Hd) 6.252 4.584 8.048 6.814
Convergence, Y/N Yes Yes Yes Yes
Cap 578 798 448 529
Service Time 4.252 2.603 5.748 4.514
HCM Lane V/C Ratio 0.234 1.266 0.1 0.047
HCM Control Delay, s/veh 10.9 154.4 11.6 9.8
HCM Lane LOS B F B A
HCM 95th-tile Q 0.8 37.9 0.3 0.1
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026
GAD DESIGN
AM PEAK HOUR
HCM 7th Signalized Intersection Summary
3: US 101 NB Off/US 101 NB On & Prado Rd 01_GAD AM
City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 1
Movement EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR Lane Configurations
Traffic Volume (veh/h) 100 950 0 0 420 350 240 0 300 0 0 0 Future Volume (veh/h) 100 950 0 0 420 350 240 0 300 0 0 0 Initial Q (Qb), veh 0 0 0 0 0 0 0 0 0
Lane Width Adj. 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Ped-Bike Adj(A_pbT) 1.00 1.00 1.00 0.95 1.00 1.00
Parking Bus, Adj 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Work Zone On Approach No No No
Adj Sat Flow, veh/h/ln 1841 1841 0 0 1841 1841 1841 0 1841 Adj Flow Rate, veh/h 100 950 0 0 420 350 240 0 300
Peak Hour Factor 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Percent Heavy Veh, % 4 4 0 0 4 4 4 0 4
Cap, veh/h 143 1098 0 0 792 637 411 0 366
Arrive On Green 0.08 0.60 0.00 0.00 0.43 0.43 0.23 0.00 0.23 Sat Flow, veh/h 1753 1841 0 0 1841 1480 1753 0 1560
Grp Volume(v), veh/h 100 950 0 0 420 350 240 0 300
Grp Sat Flow(s),veh/h/ln 1753 1841 0 0 1841 1480 1753 0 1560 Q Serve(g_s), s 3.3 25.5 0.0 0.0 10.0 10.4 7.2 0.0 10.8 Cycle Q Clear(g_c), s 3.3 25.5 0.0 0.0 10.0 10.4 7.2 0.0 10.8 Prop In Lane 1.00 0.00 0.00 1.00 1.00 1.00
Lane Grp Cap(c), veh/h 143 1098 0 0 792 637 411 0 366
V/C Ratio(X) 0.70 0.87 0.00 0.00 0.53 0.55 0.58 0.00 0.82 Avail Cap(c_a), veh/h 592 1555 0 0 1555 1250 592 0 527
HCM Platoon Ratio 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Upstream Filter(I) 1.00 1.00 0.00 0.00 1.00 1.00 1.00 0.00 1.00 Uniform Delay (d), s/veh 26.5 10.0 0.0 0.0 12.4 12.6 20.1 0.0 21.5 Incr Delay (d2), s/veh 6.0 3.9 0.0 0.0 0.6 0.7 1.3 0.0 6.7 Initial Q Delay(d3), s/veh 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 %ile BackOfQ(50%),veh/ln 1.5 8.1 0.0 0.0 3.5 3.0 2.7 0.0 4.0 Unsig. Movement Delay, s/veh
LnGrp Delay(d), s/veh 32.5 13.8 0.0 0.0 13.0 13.3 21.4 0.0 28.2 LnGrp LOS C B B B C C
Approach Vol, veh/h 1050 770 540
Approach Delay, s/veh 15.6 13.1 25.2
Approach LOS B B C
Timer - Assigned Phs 2 5 6 8
Phs Duration (G+Y+Rc), s 40.3 9.8 30.5 18.9
Change Period (Y+Rc), s 5.0 5.0 5.0 5.0
Max Green Setting (Gmax), s 50.0 20.0 50.0 20.0
Max Q Clear Time (g_c+I1), s 27.5 5.3 12.4 12.8
Green Ext Time (p_c), s 7.8 0.2 4.3 1.1
Intersection Summary
HCM 7th Control Delay, s/veh 17.0
HCM 7th LOS B
Queues
3: US 101 NB Off/US 101 NB On & Prado Rd 01_GAD AM
City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 1
Lane Group EBL EBT WBT WBR NBL NBR
Lane Group Flow (vph) 100 950 420 350 240 300
v/c Ratio 0.43 0.90 0.56 0.44 0.49 0.69
Control Delay (s/veh) 36.3 25.7 20.9 3.9 28.3 35.9
Queue Delay 0.0 0.0 0.0 0.0 0.0 0.0
Total Delay (s/veh) 36.3 25.7 20.9 3.9 28.3 35.9
Queue Length 50th (ft) 44 341 152 0 95 127
Queue Length 95th (ft) 95 544 259 51 188 #281
Internal Link Dist (ft) 786 602
Turn Bay Length (ft) 130 330
Base Capacity (vph) 487 1794 1283 1105 487 436
Starvation Cap Reductn 000000
Spillback Cap Reductn 000000
Storage Cap Reductn 000000
Reduced v/c Ratio 0.21 0.53 0.33 0.32 0.49 0.69
Intersection Summary
# 95th percentile volume exceeds capacity, queue may be longer.
Queue shown is maximum after two cycles.
HCM 7th Signalized Intersection Summary
6: Elks Lane & Prado Rd 01_GAD AM
City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 2
Movement EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR Lane Configurations
Traffic Volume (veh/h) 40 1170 40 20 730 20 10 5 5 40 20 30 Future Volume (veh/h) 40 1170 40 20 730 20 10 5 5 40 20 30 Initial Q (Qb), veh 0 0 0 0 0 0 0 0 0 0 0 0
Lane Width Adj. 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Ped-Bike Adj(A_pbT) 1.00 0.95 1.00 0.95 1.00 0.96 1.00 0.97 Parking Bus, Adj 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Work Zone On Approach No No No No
Adj Sat Flow, veh/h/ln 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 Adj Flow Rate, veh/h 40 1170 40 20 730 20 10 5 5 40 20 30 Peak Hour Factor 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Percent Heavy Veh, % 4 4 4 4 4 4 4 4 4 4 4 4
Cap, veh/h 82 1586 54 49 1532 42 27 137 137 82 128 193
Arrive On Green 0.05 0.46 0.46 0.03 0.44 0.44 0.02 0.17 0.17 0.05 0.20 0.20 Sat Flow, veh/h 1753 3443 118 1753 3471 95 1753 828 828 1753 651 977 Grp Volume(v), veh/h 40 594 616 20 368 382 10 0 10 40 0 50 Grp Sat Flow(s),veh/h/ln 1753 1749 1812 1753 1749 1818 1753 0 1655 1753 0 1629 Q Serve(g_s), s 1.5 18.5 18.6 0.8 9.9 9.9 0.4 0.0 0.3 1.5 0.0 1.7 Cycle Q Clear(g_c), s 1.5 18.5 18.6 0.8 9.9 9.9 0.4 0.0 0.3 1.5 0.0 1.7 Prop In Lane 1.00 0.06 1.00 0.05 1.00 0.50 1.00 0.60
Lane Grp Cap(c), veh/h 82 806 835 49 772 802 27 0 274 82 0 321 V/C Ratio(X) 0.48 0.74 0.74 0.41 0.48 0.48 0.38 0.00 0.04 0.48 0.00 0.16 Avail Cap(c_a), veh/h 262 1569 1626 262 1569 1631 262 0 619 262 0 609 HCM Platoon Ratio 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Upstream Filter(I) 1.00 1.00 1.00 1.00 1.00 1.00 1.00 0.00 1.00 1.00 0.00 1.00 Uniform Delay (d), s/veh 31.1 14.7 14.7 32.0 13.2 13.2 32.6 0.0 23.4 31.1 0.0 22.2 Incr Delay (d2), s/veh 4.4 1.3 1.3 5.4 0.5 0.4 8.5 0.0 0.1 4.4 0.0 0.2 Initial Q Delay(d3), s/veh 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 %ile BackOfQ(50%),veh/ln 0.7 6.5 6.8 0.4 3.5 3.6 0.2 0.0 0.1 0.7 0.0 0.7 Unsig. Movement Delay, s/veh
LnGrp Delay(d), s/veh 35.4 16.1 16.0 37.4 13.7 13.6 41.1 0.0 23.5 35.4 0.0 22.5 LnGrp LOS D B B D B B D C D C
Approach Vol, veh/h 1250 770 20 90
Approach Delay, s/veh 16.7 14.3 32.3 28.2
Approach LOS B B C C
Timer - Assigned Phs 12345678
Phs Duration (G+Y+Rc), s 6.9 35.8 6.0 18.2 8.1 34.5 8.1 16.1 Change Period (Y+Rc), s 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Max Green Setting (Gmax), s 10.0 60.0 10.0 25.0 10.0 60.0 10.0 25.0 Max Q Clear Time (g_c+I1), s 2.8 20.6 2.4 3.7 3.5 11.9 3.5 2.3 Green Ext Time (p_c), s 0.0 10.2 0.0 0.2 0.0 5.2 0.0 0.0 Intersection Summary
HCM 7th Control Delay, s/veh 16.4
HCM 7th LOS B
Queues
6: Elks Lane & Prado Rd 01_GAD AM
City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 2
Lane Group EBL EBT WBL WBT NBL NBT SBL SBT
Lane Group Flow (vph) 40 1210 20 750 10 10 40 50
v/c Ratio 0.15 0.49 0.08 0.30 0.04 0.04 0.15 0.17
Control Delay (s/veh) 30.6 9.4 32.0 8.1 32.9 32.5 30.6 19.5 Queue Delay 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0
Total Delay (s/veh) 30.6 9.4 32.0 8.1 32.9 32.5 30.6 19.5 Queue Length 50th (ft) 8 77 4 392284
Queue Length 95th (ft) 57 356 36 196 23 23 57 48
Internal Link Dist (ft) 602 903 272 534
Turn Bay Length (ft) 240 190 100 100
Base Capacity (vph) 374 3143 374 3148 374 892 374 888
Starvation Cap Reductn 0 513000000
Spillback Cap Reductn 00000000
Storage Cap Reductn 00000000
Reduced v/c Ratio 0.11 0.46 0.05 0.24 0.03 0.01 0.11 0.06 Intersection Summary
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026
GAD DESIGN
PM PEAK HOUR
HCM 7th Signalized Intersection Summary
3: US 101 NB Off/US 101 NB On & Prado Rd 01_GAD PM
City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 2
Movement EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR Lane Configurations
Traffic Volume (veh/h) 100 600 0 0 910 780 180 0 150 0 0 0 Future Volume (veh/h) 100 600 0 0 910 780 180 0 150 0 0 0 Initial Q (Qb), veh 0 0 0 0 0 0 0 0 0
Lane Width Adj. 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Ped-Bike Adj(A_pbT) 1.00 1.00 1.00 0.96 1.00 1.00
Parking Bus, Adj 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Work Zone On Approach No No No
Adj Sat Flow, veh/h/ln 1841 1841 0 0 1841 1841 1841 0 1841 Adj Flow Rate, veh/h 100 600 0 0 910 780 180 0 150
Peak Hour Factor 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Percent Heavy Veh, % 4 4 0 0 4 4 4 0 4
Cap, veh/h 130 1347 0 0 1087 882 237 0 211
Arrive On Green 0.07 0.73 0.00 0.00 0.59 0.59 0.14 0.00 0.14 Sat Flow, veh/h 1753 1841 0 0 1841 1493 1753 0 1560
Grp Volume(v), veh/h 100 600 0 0 910 780 180 0 150
Grp Sat Flow(s),veh/h/ln 1753 1841 0 0 1841 1493 1753 0 1560 Q Serve(g_s), s 4.2 9.7 0.0 0.0 30.0 33.6 7.4 0.0 6.9
Cycle Q Clear(g_c), s 4.2 9.7 0.0 0.0 30.0 33.6 7.4 0.0 6.9 Prop In Lane 1.00 0.00 0.00 1.00 1.00 1.00
Lane Grp Cap(c), veh/h 130 1347 0 0 1087 882 237 0 211
V/C Ratio(X) 0.77 0.45 0.00 0.00 0.84 0.88 0.76 0.00 0.71 Avail Cap(c_a), veh/h 467 1347 0 0 1226 995 467 0 416
HCM Platoon Ratio 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Upstream Filter(I) 1.00 1.00 0.00 0.00 1.00 1.00 1.00 0.00 1.00 Uniform Delay (d), s/veh 34.1 4.0 0.0 0.0 12.4 13.2 31.3 0.0 31.1 Incr Delay (d2), s/veh 9.0 0.2 0.0 0.0 4.8 8.8 5.0 0.0 4.4 Initial Q Delay(d3), s/veh 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 %ile BackOfQ(50%),veh/ln 2.0 2.3 0.0 0.0 11.2 11.0 3.2 0.0 2.7 Unsig. Movement Delay, s/veh
LnGrp Delay(d), s/veh 43.1 4.2 0.0 0.0 17.2 22.0 36.2 0.0 35.5 LnGrp LOS D A B C D D
Approach Vol, veh/h 700 1690 330
Approach Delay, s/veh 9.8 19.4 35.9
Approach LOS A B D
Timer - Assigned Phs 2 5 6 8
Phs Duration (G+Y+Rc), s 59.9 10.6 49.3 15.1
Change Period (Y+Rc), s 5.0 5.0 5.0 5.0
Max Green Setting (Gmax), s 50.0 20.0 50.0 20.0
Max Q Clear Time (g_c+I1), s 11.7 6.2 35.6 9.4
Green Ext Time (p_c), s 4.4 0.2 8.7 0.7
Intersection Summary
HCM 7th Control Delay, s/veh 18.9
HCM 7th LOS B
Queues
3: US 101 NB Off/US 101 NB On & Prado Rd 01_GAD PM
City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 1
Lane Group EBL EBT WBT WBR NBL NBR
Lane Group Flow (vph) 100 600 910 780 180 150
v/c Ratio 0.49 0.45 0.86 0.72 0.65 0.60
Control Delay (s/veh) 46.3 6.7 29.1 8.0 46.9 46.1
Queue Delay 0.0 0.0 1.0 0.0 0.0 0.0
Total Delay (s/veh) 46.3 6.7 30.1 8.0 46.9 46.1
Queue Length 50th (ft) 56 118 443 45 100 83
Queue Length 95th (ft) 113 223 #871 238 179 154
Internal Link Dist (ft) 786 602
Turn Bay Length (ft) 130 330
Base Capacity (vph) 401 1552 1058 1085 401 358
Starvation Cap Reductn 0 0 36000
Spillback Cap Reductn 000000
Storage Cap Reductn 000000
Reduced v/c Ratio 0.25 0.39 0.89 0.72 0.45 0.42
Intersection Summary
# 95th percentile volume exceeds capacity, queue may be longer.
Queue shown is maximum after two cycles.
HCM 7th Signalized Intersection Summary
6: Elks Lane & Prado Rd 01_GAD PM
City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 4
Movement EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR Lane Configurations
Traffic Volume (veh/h) 50 690 10 10 1600 20 30 20 20 50 10 60 Future Volume (veh/h) 50 690 10 10 1600 20 30 20 20 50 10 60 Initial Q (Qb), veh 0 0 0 0 0 0 0 0 0 0 0 0
Lane Width Adj. 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Ped-Bike Adj(A_pbT) 1.00 0.96 1.00 0.96 1.00 0.96 1.00 0.96 Parking Bus, Adj 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Work Zone On Approach No No No No
Adj Sat Flow, veh/h/ln 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 1841 Adj Flow Rate, veh/h 50 690 10 10 1600 20 30 20 20 50 10 60 Peak Hour Factor 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Percent Heavy Veh, % 4 4 4 4 4 4 4 4 4 4 4 4
Cap, veh/h 82 2019 29 26 1910 24 61 123 123 82 36 214
Arrive On Green 0.05 0.57 0.57 0.01 0.54 0.54 0.03 0.15 0.15 0.05 0.16 0.16 Sat Flow, veh/h 1753 3526 51 1753 3535 44 1753 826 826 1753 220 1322 Grp Volume(v), veh/h 50 342 358 10 791 829 30 0 40 50 0 70 Grp Sat Flow(s),veh/h/ln 1753 1749 1829 1753 1749 1830 1753 0 1651 1753 0 1543 Q Serve(g_s), s 2.6 9.6 9.6 0.5 35.1 35.2 1.6 0.0 2.0 2.6 0.0 3.7 Cycle Q Clear(g_c), s 2.6 9.6 9.6 0.5 35.1 35.2 1.6 0.0 2.0 2.6 0.0 3.7 Prop In Lane 1.00 0.03 1.00 0.02 1.00 0.50 1.00 0.86
Lane Grp Cap(c), veh/h 82 1001 1047 26 945 989 61 0 247 82 0 249 V/C Ratio(X) 0.61 0.34 0.34 0.39 0.84 0.84 0.49 0.00 0.16 0.61 0.00 0.28 Avail Cap(c_a), veh/h 190 1135 1187 190 1135 1188 190 0 446 190 0 417 HCM Platoon Ratio 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Upstream Filter(I) 1.00 1.00 1.00 1.00 1.00 1.00 1.00 0.00 1.00 1.00 0.00 1.00 Uniform Delay (d), s/veh 43.2 10.5 10.5 45.1 17.8 17.9 43.8 0.0 34.3 43.2 0.0 34.0 Incr Delay (d2), s/veh 7.0 0.2 0.2 9.3 4.8 4.7 6.0 0.0 0.3 7.0 0.0 0.6 Initial Q Delay(d3), s/veh 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 %ile BackOfQ(50%),veh/ln 1.3 3.4 3.6 0.3 13.8 14.5 0.8 0.0 0.8 1.3 0.0 1.4 Unsig. Movement Delay, s/veh
LnGrp Delay(d), s/veh 50.3 10.7 10.7 54.4 22.6 22.5 49.8 0.0 34.6 50.3 0.0 34.7 LnGrp LOS D B B D C C D C D C
Approach Vol, veh/h 750 1630 70 120
Approach Delay, s/veh 13.3 22.8 41.1 41.2
Approach LOS B C D D
Timer - Assigned Phs 12345678
Phs Duration (G+Y+Rc), s 6.4 57.9 8.2 19.9 9.3 55.0 9.3 18.8 Change Period (Y+Rc), s 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Max Green Setting (Gmax), s 10.0 60.0 10.0 25.0 10.0 60.0 10.0 25.0 Max Q Clear Time (g_c+I1), s 2.5 11.6 3.6 5.7 4.6 37.2 4.6 4.0 Green Ext Time (p_c), s 0.0 4.8 0.0 0.3 0.0 12.7 0.0 0.1 Intersection Summary
HCM 7th Control Delay, s/veh 21.4
HCM 7th LOS C
Queues
6: Elks Lane & Prado Rd 01_GAD PM
City of SLO - US101 Prado Road Interchange Prado Rd.syn DKS Associates Page 3
Lane Group EBL EBT WBL WBT NBL NBT SBL SBT
Lane Group Flow (vph) 50 700 10 1620 30 40 50 70
v/c Ratio 0.30 0.27 0.07 0.71 0.20 0.24 0.30 0.32
Control Delay (s/veh) 50.6 7.2 49.6 18.5 49.5 49.3 50.6 19.9 Queue Delay 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Total Delay (s/veh) 50.6 7.2 49.6 18.5 49.5 49.3 50.6 19.9 Queue Length 50th (ft) 33 83 7 444 20 27 33 7
Queue Length 95th (ft) 75 180 26 633 52 63 75 51
Internal Link Dist (ft) 602 903 272 534
Turn Bay Length (ft) 240 190 100 100
Base Capacity (vph) 216 2585 216 2378 216 516 216 520
Starvation Cap Reductn 00000000
Spillback Cap Reductn 00000000
Storage Cap Reductn 00000000
Reduced v/c Ratio 0.23 0.27 0.05 0.68 0.14 0.08 0.23 0.13 Intersection Summary
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 SECTION 2: VISSIM RESULTS
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026
NO BUILD
AM PEAK HOUR
City of SLO - US101 Prado Road Interchange No Build AM
Intersection Approach Movement
Demand
Volume
Served
Volume % Served GEH
Average
Delay (s) LOS
Left - -
Through 30 34 113% 0.7 8 A
Right 310 308 99% 0.1 4 A
U-Turn - -
Total 340 342 101% 0.1 4 A
Left 55 54 98% 0.1 6 A
Through - -
Right 15 14 93% 0.3 3 A
U-Turn - -
Total 70 68 97% 0.2 5 A
Left - -
Through - -
Right - -
U-Turn - -
Total - - 0
Left - -
Through 565 563 100% 0.1 30 D
Right 15 15 100% 0.0 22 C
U-Turn - -
Total 580 578 100% 0.1 30 D
988 990 100% 0.1 19 C
EB
WB
TABLE: AVERAGE DELAY
Total
US 101 Ramps /
Prado Rd / Elks Ln
NB
SB
DKS Associates Page 232 of 1065 5/8/2026
City of SLO - US101 Prado Road Interchange No Build AM
20 (60)
225 (475)
40 (120)
TABLE: QUEUE COUNTERS (Avg/95th)
1: US 101 Ramps / Prado Rd /
Elks Ln
DKS Associates Page 233 of 1065 5/8/2026
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026
NO BUILD
PM PEAK HOUR
City of SLO - US101 Prado Road Interchange No Build PM
Intersection Approach Movement
Demand
Volume
Served
Volume % Served GEH
Average
Delay (s) LOS
Left - -
Through 10 11 110% 0.3 7 A
Right 125 123 98% 0.2 2 A
U-Turn - -
Total 135 134 99% 0.1 2 A
Left 45 44 98% 0.1 6 A
Through - -
Right 25 23 92% 0.4 4 A
U-Turn - -
Total 70 67 96% 0.4 5 A
Left - -
Through - -
Right - -
U-Turn - -
Total - - 0
Left - -
Through 980 600 61% 13.5 267 F
Right 30 19 63% 2.2 260 F
U-Turn - -
Total 1010 619 61% 13.7 267 F
820 1215 67% 12.4 202 F
TABLE: AVERAGE DELAY
Total
US 101 Ramps /
Prado Rd / Elks Ln
NB
SB
EB
WB
DKS Associates Page 235 of 1065 5/8/2026
City of SLO - US101 Prado Road Interchange No Build PM
20 (60)
1545 (1690)
10 (60)
TABLE: QUEUE COUNTERS (Avg/95th)
1: US 101 Ramps / Prado Rd /
Elks Ln
DKS Associates Page 236 of 1065 5/8/2026
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026
GAD DESIGN
AM PEAK HOUR
City of SLO - US101 Prado Road Interchange GED Design AM Intersection Approach Movement
Demand
Volume
Served
Volume % Served GEH
Average
Delay (s) LOS
Left 240 236 98% 0.3 35 C
Through - -
Right 300 303 101% 0.2 36 D
U-Turn - -
Total 540 539 100% 0.0 35 D
Left - -
Through - -
Right - -
U-Turn - -
Total - - 0
Left 100 98 98% 0.2 42 D
Through 950 947 100% 0.1 16 B
Right - -
U-Turn - -
Total 1050 1045 100% 0.2 18 B
Left - -
Through 420 417 99% 0.1 16 B
Right 350 351 100% 0.1 10 A
U-Turn - -
Total 770 768 100% 0.1 13 B
2352 2360 100% 0.2 20 C
Left 10 10 100% 0.0 51 D
Through 5 5 100% 0.0 43 D
Right 5 4 80% 0.5 39 D
U-Turn - -
Total 20 19 95% 0.2 47 D
Left 40 40 100% 0.0 46 D
Through 20 20 100% 0.0 33 C
Right 30 29 97% 0.2 9 A
U-Turn - -
Total 90 89 99% 0.1 31 C
Left 40 37 93% 0.5 40 D
Through 1170 1176 101% 0.2 11 B
Right 40 39 98% 0.2 9 A
U-Turn - -
Total 1250 1252 100% 0.1 12 B
Left 20 19 95% 0.2 42 D
Through 730 729 100% 0.0 13 B
Right 20 21 105% 0.2 9 A
U-Turn - -
Total 770 769 100% 0.0 14 B
2129 2130 100% 0.0 14 B
TABLE: AVERAGE DELAY
Total
Total
Elks Ln / Prado Rd
NB
SB
EB
WB
US 101 Ramps /
Prado Rd
NB
SB
EB
WB
DKS Associates Page 238 of 1065 5/8/2026
City of SLO - US101 Prado Road Interchange GAD Design AM
75 (155) 135 (375)
390 (855) 160 (380)
125 (240) 175 (345)
25 (75) 35 (85)
30 (70)
185 (325) 150 (310)
20 (60)
10 (45) 10 (40)
TABLE: QUEUE COUNTERS (Avg/95th)
1: US 101 Ramps / Prado Rd
2: Elks Ln / Prado Rd
DKS Associates Page 239 of 1065 5/8/2026
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026
GAD DESIGN
PM PEAK HOUR
City of SLO - US101 Prado Road Interchange GAD Design PM Intersection Approach Movement
Demand
Volume
Served
Volume % Served GEH
Average
Delay (s) LOS
Left 180 178 99% 0.1 36 D
Through - -
Right 150 152 101% 0.2 31 C
U-Turn - -
Total 330 330 100% 0.0 34 C
Left - -
Through - -
Right - -
U-Turn - -
Total - - 0
Left 100 95 95% 0.5 36 D
Through 600 603 101% 0.1 8 A
Right - -
U-Turn - -
Total 700 698 100% 0.1 11 B
Left - -
Through 910 900 99% 0.3 17 B
Right 780 787 101% 0.3 23 C
U-Turn - -
Total 1690 1687 100% 0.1 20 B
2715 2720 100% 0.1 19 B
Left 30 28 93% 0.4 55 D
Through 20 21 105% 0.2 43 D
Right 20 18 90% 0.5 36 D
U-Turn - -
Total 70 67 96% 0.4 46 D
Left 50 52 104% 0.3 50 D
Through 10 11 110% 0.3 48 D
Right 60 58 97% 0.3 17 B
U-Turn - -
Total 120 121 101% 0.1 34 C
Left 50 50 100% 0.0 59 E
Through 690 694 101% 0.2 10 A
Right 10 8 80% 0.7 7 A
U-Turn - -
Total 750 752 100% 0.1 13 B
Left 10 8 80% 0.7 68 E
Through 1600 1595 100% 0.1 30 C
Right 20 20 100% 0.0 27 C
U-Turn - -
Total 1630 1623 100% 0.2 30 C
2563 2570 100% 0.1 26 C
EB
WB
TABLE: AVERAGE DELAY
Total
Total
Elks Ln / Prado Rd
NB
SB
EB
WB
US 101 Ramps /
Prado Rd
NB
SB
DKS Associates Page 241 of 1065 5/8/2026
City of SLO - US101 Prado Road Interchange GAD Design PM
65 (135) 455 (735)
135 (320) 455 (740)
100 (200) 85 (180)
35 (90) 40 (95)
45 (105)
105 (220) 545 (945)
10 (45)
25 (65) 30 (80)
TABLE: QUEUE COUNTERS (Avg/95th)
1: US 101 Ramps / Prado Rd
2: Elks Ln / Prado Rd
DKS Associates Page 242 of 1065 5/8/2026
US 101 AND PRADO ROAD INTERCHANGE • GAD TRAFFIC ANALYSIS • MAY 2026 SECTION 3: LEISCH METHOD RESULTS
Number of Entering Mainline Lanes Nb 2 Project
Number of Lanes in Weaving Section N 3 ScenarioLength of Weaving Section (feet) L 1,330 Peak FreewayOn-ramp
Volume (vph)* 3,175 Volume (vph)* 450 Volume (vph)* 155 Off-rampTruck Percentage 2.0% Truck Percentage 10.2% Truck Percentage 10.0%PCE for Trucks 2.0 PCE for Trucks 2.0 PCE for Trucks 2.0Volume (pcph) 3,237 Volume (pcph) 496 Volume (pcph) 171 666
Figure
US 101 NB
Prado Rd Madonna Rd
V1. Is the weaving section balanced (Y / N)? N
If optional exit lane, then "Y". Otherwise "N".
2. In the chart to the left, which two speed curves is the red "x" between? 50 MPH and 55 MPH
If left of the 30 MPH curve, LOS is F. Select "-". If below the 55 MPH curve, out of the realm of weaving.
3. Interpolated Weaving Speed (Sw, mph) 52.5
4. Weaving Intensity Factor (k) 1.005. Service Volume (SV, pcph) SV = (1/N)*[V + (k - 1)*min(W1, W2)] 1,079
6. Level of Service (LOS) C
The LOS in the chart above refers to the capacity of weaving traffic only; through and ramp to ramp traffic is not included.* Note: Do not adjust by a Peak Hour Factor (PHF). The methodology incorporates the PHF in the Service Volume tables.
Sources: Completion of Procedures for Analysis and Design of Traffic Weaving Sections , Jack E. Leisch & Associates, September 1983 and Highway Design Manual , California Department of Transportation, 2014 W1+W2
Capacity Analysis
US 101 NB
Total Weaving Section (V) On-ramp to Mainline (W1) Mainline to Off-ramp (W2) Prado Rd Madonna Rd
AM
Leisch Method for Weaving Analysis
Data Input Project Information
US 101 Prado Road Interchange
2045 2-Lane Build
0 1000200030004000
0 1000 2000 3000 4000 5000 6000
W
1 + W2 - Weaving Volume (pcph)
L - Length of Weaving Section (feet)
A
B
C
D
E
55 MPH
30 MPH
35 MPH
40 MPH
45 MPH
OUT OF REALM OF WEAVING
50 MPH
F
Nb N
L
Balanced SectionImbalanced Section
Number of Entering Mainline Lanes Nb 2 Project
Number of Lanes in Weaving Section N 3 ScenarioLength of Weaving Section (feet) L 1,330 Peak FreewayOn-ramp
Volume (vph)* 3,630 Volume (vph)* 935 Volume (vph)* 160 Off-rampTruck Percentage 1.0% Truck Percentage 2.0% Truck Percentage 2.5%PCE for Trucks 2.0 PCE for Trucks 2.0 PCE for Trucks 2.0Volume (pcph) 3,665 Volume (pcph) 954 Volume (pcph) 164 1,118
Figure
US 101 NB
Prado Rd Madonna Rd
V1. Is the weaving section balanced (Y / N)? N
If optional exit lane, then "Y". Otherwise "N".
2. In the chart to the left, which two speed curves is the red "x" between? 40 MPH and 45 MPH
If left of the 30 MPH curve, LOS is F. Select "-". If below the 55 MPH curve, out of the realm of weaving.
3. Interpolated Weaving Speed (Sw, mph) 44.2
4. Weaving Intensity Factor (k) 2.815. Service Volume (SV, pcph) SV = (1/N)*[V + (k - 1)*min(W1, W2)] 1,321
6. Level of Service (LOS) D
The LOS in the chart above refers to the capacity of weaving traffic only; through and ramp to ramp traffic is not included.* Note: Do not adjust by a Peak Hour Factor (PHF). The methodology incorporates the PHF in the Service Volume tables.
Sources: Completion of Procedures for Analysis and Design of Traffic Weaving Sections , Jack E. Leisch & Associates, September 1983 and Highway Design Manual , California Department of Transportation, 2014 W1+W2
Capacity Analysis
US 101 NB
Total Weaving Section (V) On-ramp to Mainline (W1) Mainline to Off-ramp (W2) Prado Rd Madonna Rd
PM
Leisch Method for Weaving Analysis
Data Input Project Information
US 101 Prado Road Interchange
2045 2-Lane Build
0 1000200030004000
0 1000 2000 3000 4000 5000 6000
W
1 + W2 - Weaving Volume (pcph)
L - Length of Weaving Section (feet)
A
B
C
D
E
55 MPH
30 MPH
35 MPH
40 MPH
45 MPH
OUT OF REALM OF WEAVING
50 MPH
F
Nb N
L
Balanced SectionImbalanced Section
D
D
D
D
D
D
D
D
D
D
D
D
15' WIDE JUA-UNION OIL CO. DOC. NO. 2994-B 1238-OR-501
PRADO ROAD US 101 SB
February 2026 US 101 NB
HIGUERA STREET
D
D
D
D
D
D
D
15' WIDE JUA-UNION OIL CO. DOC. NO. 2994-B 1238-OR-501
15' WIDE JUA-UNION OIL CO. DOC. NO. 2994-B
1238-OR-501
US 101 SB US 101 NB
ELKS LANE
Exist Basin 1
Exist Basin 2
(Relocated) Exist Basin
5 SCM 2
BMP 1
SCM 1
Exist Basin 6
Exist Basin 4
Exist Basin 3
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D D D D D D D
D D D D D D
D
D
D
D
D
D
D
D
D
D
PRADO ROAD US 101 SB
May 2026 US 101 NB
HIGUERA STREET
US 101 Prado Road Interchange Proposed Watershed Exhibit EA 05-1H640
Exist Strip 1
Exist Strip 2 BMP 1
SCM 1 Exist Basin 3
D
D
D
D
D
D
D
D
D
D
D
D D
US 101 SB US 101 NB
ELKS LANE
D D D D D D D D D D D D D D D D D D D D D D D D D D D DD D D D D D D D D D PRADO ROAD US 101 SB
June 2026 US 101 NB HIGUERA STREET
US 101 Prado Road Interchange Proposed Drainage Exhibit DRAFT EA 05-1H640
D
D
D
D
D
D
D
D
D
D
D
D D
US 101 SB US 101 NB
ELKS LANE
CO / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / // / / / / / / / / / / // / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / JP RSR PP BOX ELEC ELEC ELEC GM G G G G G GV RSR RSR SLB SLB TCOM TCOM TCOM TCOM TCOM T T JP+ PP+ PP+ EM JP+ EM EM G G ELEC TCOM TCOM ELEC VLT VLT PP CO RSR T RSR EMRSR ELECRSR RSR EM JP JP+ JP+ VLT JP EM JP + ELEC ELEC T TCOM GV T RSR G T G G TCOM ELEC ELEC ELEC TCOM JP+ JP+ JP+ JP+ JP+ JP TP TP JP+ JP+ JP JP / / / / / / / / / / / / ELEC TVLT PP D D D S S S D D S D RCW S SS SS SS SS SS SS SS SS SS PROPOSED WET UTILITIES WITH PROPOSED ROADWAY EXHIBIT ELKS LANE PRADO ROAD
ELKS LANE
US 101 SB US 101 NB Page 252 of 1065
D218721CA.00 • March 2026 • City of San Luis Obispo
Prado Road Interchange • 1
Prado Road Transmission Main Options Analysis
Date: April 20, 2026
Project: Prado Road Interchange
To: Matt Horn, PE
City of San Luis Obispo
From: Nickolas Buonarati, EIT
Consor
Reviewed By: Adam Blair, PE
Consor
Re: Prado Road Transmission Main Options Analysis
Introduction
The City of San Luis Obispo (City) has retained Consor North America (Consor) to design a new partial interchange at US 101 and Prado Road (project, overpass), to allow for a new crossing over the US 101 (highway). Part of the project’s scope includes upgrades to existing utilities located on Prado Road, including a 12-inch diameter cast iron water main (main). During design, Consor determined that the new overpass will impact an existing segment of this main that crosses the highway. This line is critical to maintaining the City’s robustness, connecting the east and west sides of the city.
Consor has identified four options that could provide additional connectivity to the east side of the highway near Prado Road. These four options are outlined below followed by a summary table of the considerations for each option.
Option 1: Jack and Bore Under Highway
Trenchless pipeline installation is commonly used where open-cut pipe installation will cause increased risks, traffic disruptions, or environmental impacts. Option 1 utilizes the jack-and-bore method to install the 12-inch diameter main beneath the highway, minimizing surface disturbance. This approach is a costeffective solution for this location.
Jack and bore trenchless methods involve excavating a launch pit and a smaller receiving pit, which are typically designed by the contractor. The launch pit will then be used to bore the alignment while jacking a 42-inch-diameter steel casing under the highway. An internal auger unit in the casing removes soils back to the launch pit for hauling and disposal. Once the casing is installed between the launch and receiving pits, the 12-inch diameter main can be installed within the casing, connected to the existing piping at either end, and the pits can be backfilled.
Even though no surface impacts are anticipated, an encroachment permit will still need to be acquired from the California Department of Transportation (Caltrans), as work will still be happening within their right-ofway.
D218721CA.00 • April 2026 • City of San Luis Obispo
Prado Road Interchange • 2
As outlined below, Consor has evaluated two potential locations for this work. For both options, Consor currently estimates the construction at $1,150,000 (based on 2026 unit prices, including a 50% Contingency and not including the cost to obtain easements). Although Option 1B is a slightly longer crossing, the cost is assumed the same as Option 1 for this high-level estimation.
Option 1A: El Mercado to Elks Lane
Option 1 utilizes a corridor crossing of the highway at El Mercado Street. The launch pit is excavated at the end of El Mercado, on the west side of US-101. The casing is then bored beneath US-101, towards the receiving pit excavated east of US-101, at Elks Lane (old). Error! Reference source not found. below illustrates this configuration.
Figure 1: El Mercado to Elks Lane (Old)
D218721CA.00 • April 2026 • City of San Luis Obispo
Prado Road Interchange • 3
Option 1B: Elks Lane to Embassy Suites Parking Lot
An alternative to Option 1A is to excavate a launch pit at the corner where Elks Lane (new) starts and bore west beneath US-101 to a receiving pit located within the Embassy Suites parking lot property, necessitating an easement. A potential permitting concern is that this alignment has a larger skew angle than the option outlined above, deviating from a preferred perpendicular crossing. Option 1B is shown in Figure 2 below.
Figure 2: Elks Lane (new) to Embassy Suites Parking Lot Alternatively, if the city does not want to obtain an easement from the Embassy Suites, they could instead obtain two easements from the empty lots south of the Embassy Suites, with access to the receiving pit just south of the property line between these lots and the parking lot.
Easement requirements are outlined in Table 1 and Figure 3 below.
D218721CA.00 • April 2026 • City of San Luis Obispo
Prado Road Interchange • 4
Table 1: Easements for Option 1B
APN Number Parcel Number
Embassy Suites Parking Easement
053-012-030 030
Empty Lot Easements
053-153-007 007
053-153-012 012
Figure 3: Easements needed for Option 1B
D218721CA.00 • April 2026 • City of San Luis Obispo
Prado Road Interchange • 5
Option 2: Northern Extension of Calle Joaquin Main
Option 2 creates east-west connectivity north of Prado Road by extending an existing watermain that currently dead-ends in the cul-de-sac at Calle Joaquin (See Figure 4 for location). From Calle Joaquin the new main would travel north, parallel to the southbound lane to the highway until it meets the existing line at the new Prado Road overpass. This option would be installed utilizing open-cut trenching for the approximate 3,000 LF of new 12-inch ductile iron pipe, with limited, if any, impact to the highway. This option requires utilizing both new and existing City easements with properties adjacent to Caltrans rightof-way on the east side of the highway. Easement needs are outlined in Table 2 and Figure 4 below.
Table 2: Option 2 - Easement Needs
APN Number Parcel Number
Already Acquired Easements
053-153-013 013
053-153-014 014
Properties Requiring Easements
053-152-007 007
053-152-008 008
053-152-006 006
Currently, Consor estimates this option to be $2,300,000.00 (2026 Unit prices, including a 50% Contingency and not including cost of obtaining easements). Below, Figure 4 shows the approximate path that this waterline extension would take, alongside the easements listed in Table 2 above.
D218721CA.00 • April 2026 • City of San Luis Obispo
Prado Road Interchange • 6
Figure 4: Waterline Extension Alignment
Option 3: Waterline Over New Overpass
Option 3 replaces the existing main in Prado Road with a new alignment that crosses the highway via the new overpass. The new alignment places the 12-inch diameter main in the eastside overpass approach fills and then east to west over the highway in a 24-inch diameter steel casing within the bridge structure. At the western side of the highway, the main would extend to bridge support “Bent 3” where a 90-degree bend routes the new line down a support column and connects to the existing 12-inch diameter underground watermain. If attaching the waterline to the column if not desirable, an alternative alignment could route the main further to the west in overpass approach soils, but would result in significantly more new pipe length to connect back to the water main adjacent to the highway (not included in cost). Flexible expansion joints are used at 4 locations along the alignment to provide long-term resilience for the line at the unconstrained bridge joints.
Consor estimates this option to be approximately $1,190,000.00 (2026 Unit prices and including a 50% Contingency). Figure 5 and Figure 6 below show the general location of the waterline in relation to the overpass.
D218721CA.00 • April 2026 • City of San Luis Obispo
Prado Road Interchange • 7
Figure 5: East Side of Overpass
Figure 6: West Side of Overpass
D218721CA.00 • April 2026 • City of San Luis Obispo
Prado Road Interchange • 8
Option 4: Casing of 12-inch line in Prado
Option 4 replaces the existing water main along Prado Road with a new section of 12-inch ductile iron pipe installed within a steel casing beneath the proposed overpass island.
The existing 12-inch diameter ductile iron highway crossing at Prado Road is housed within a 24-inch casing.
The encased section extends east of the highway and terminates at a point approximately midway through the planned overpass island. Under Option 4, a new 24-inch casing is installed over the new 12-inch ductile iron pipe and extended to tie into the existing casing. This approach provides continuous encasement of the water main beneath the entirety of the new overpass island.
Consor estimates this option to be approximately $75,000.00 (2026 Unit prices and including a 50% Contingency. Cost assumes work is performed concurrent with other water utility improvements on Prado).
Figure 7 below show the general location of the waterline in relation to the overpass.
Figure 7: Pipe and Casing Under Overpass
D218721CA.00 • April 2026 • City of San Luis Obispo
Prado Road Interchange • 9
Summary
Established above, there are pros and cons for all options. Below, Table 3 illustrates these differences, while Figure 8 shows approximate locations of each option.
Based on the costs associated with the options for constructing a new crossing of US 101, Consor recommends that Option 4 be pursued by the City assuming that the existing water main and casing is in good condition. The City could pursue one of the other alternatives at a later date to provide additional east west connectivity in the area.
Table 3: Summary
Options Pros Cons Estimated
Construction
Cost
Jack and Bore Under
Highway
• Shorter span of pipe
• Less impact to
surroundings
• Harder to maintain due to
being within a highway
• Possible difficulty in
acquiring qualified
contractor
• Need for easements
• Not within current
project APE, additional
environmental review
required
$1,150,000.00
Northern Extension of
Calle Joaquin Main
• Minimal, if any, Traffic
Control
• Easier to construct
and maintain
• Larger impact to
surroundings
• Need for easements
• Not within current
project APE
• Environmental Review
required
• Most costly option
$2,300,000.00
Waterline Over New
Overpass
• Traffic Control goes
hand-in-hand with the
construction of the
overpass
• Harder to maintain due to
being underneath the
highway overpass
• Difficult to construct
$1,190,000.00
Casing of 12-inch line in
Prado
• Shortest run of pipe
• Most cost effective of
all options
• Still buried underneath
the overpass
• Assumes acceptable
condition of existing pipe
and casing crossing
highway.
$75,000.00
D218721CA.00 • April 2026 • City of San Luis Obispo
Prado Road Interchange • 10
Figure 8: General Map of All Options
Aconsor
th
5 —
a s
CITY OF SAN LUIS OBISPO
PID 0516000105
July 2, 2026
PREPARED FOR:
City of San Luis Obispo
919 Palm Street
San Luis Obispo, CA 93401
PREPARED BY:
Consor
Point of Contact: Dace Morgan, PE
2868 Prospect Park Drive, Suite 250
Rancho Cordova, CA 95630
p: 916.368.9181
e: [email protected]
Draft Prado Road Interchange Project
Bridge Type Selection Report
05-SLO-101 PM 26.8/27.3
EA-O5-1H64O
Type Selection Revisions
Revision Date Description
0 July 2, 2026 Draft Type Selection Memo
Q00FESS/ON,
(
/
Prepared by:
Tyler Z. Eaton
No C89407
* >
Tyler Eaton, Bridge Project Engineer
CIVIL
3)
QQ0FESS/ON,
(
/
Under the Supervision of: Scott McCauley
No C71495
* >
Scott McCauley, Lead Structure Project Engineer CIVIL
3)
Submitted by 07/02/2026 (916) 368-9181
TelephoneDace Morgan, Deputy Project Manager Date
Consor North America, Inc.
OF CAWS%
OF CAWS%
DRAFT
Table of Contents
Chapter 1 General Information 1-1
1.1 Structure Type Selection Summary 1-1
1.2 Introduction 1-1
1.3 General Description 1-2
1.4 Project History 1-2
1.5 Existing and Proposed Nearby Facilities 1-3
1.6 Funding 1-4
1.7 Impacts to Traffic 1-4
1.8 Staging Areas and Contractor Access 1-4
1.9 Right of Way. 1-5
1.10 Hydraulic Considerations 1-5
1.10.1 Flood plain 1-5
1.10.2 Scour 1-5
1.10.3 Drainage 1-6
1.11 Geotechnical Considerations 1-7
1.12 Seismic Ground Motion 1-7
1.13 Liquefaction and Lateral Spreading Potential 1-7
1.14 Horizontal Layout 1-8
1.15 Vertical Profile 1-8
1.15.1 Falsework 1-9
1.16 Structure Layout 1-9
1.17 Design Exceptions 1-10
1.18 Design Criteria 1-10
1.18.1 Corrosion. 1-10
1.18.2 Scour 1-10
1.19 Utilities 1-11
1.20 General Aesthetics 1-11
1.21 Approach Slabs. 1-11
1.22 Environmental Studies and Permits 1-11
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DRAFT
Chapter 2 Prado Road West Overcrossing 2-12
2.1 Preferred Structure Type Summary 2-12
2.2 Structure Type Alternatives 2-13
2.2.1 Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder (Preferred) 2-13
2.2.2 Precast, Pretensioned Reinforced Concrete California Wide Flange Grider. 2-13
2.2.3 Other Alternatives 2-13
2.3 Foundations 2-14
2.3.1 Bents 2-14
2.3.2 Abutments 2-14
2.4 Constructability 2-14
2.4.1 Falsework 2-14
2.4.2 Deep Foundations 2-15
2.4.3 MSE Wall "Island" 2-15
2.5 Barriers 2-16
2.6 Aesthetics 2-16
2.7 Cost Estimate 2-16
2.8 Recommendation 2-16
Chapter 3 Prado Road East Overcrossing 3-17
3.1 Preferred Structure Type Summary 3-17
3.2 Structure Type Alternatives 3-18
3.2.1 Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder (Preferred) 3-18
3.2.2 Precast, Pretensioned Reinforced Concrete California Wide Flange Grider. 3-18
3.2.3 Other Alternatives 3-18
3.3 Foundations 3-19
3.3.1 Bents 3-19
3.3.2 Abutments 3-19
3.4 Constructability 3-19
3.4.1 Falsework 3-19
3.4.2 Deep Foundations 3-19
3.4.3 MSE Wall "Island" 3-20
3.5 Barriers 3-20
3.6 Aesthetics 3-20
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DRAFT
3.7 Cost Estimate 3-20
3.8 Recommendation 3-21
Chapter 4 US 101 Northbound Off-Ramp Structure 4-22
4.1 Preferred Structure Type Summary 4-22
4.2 Structure Type Alternatives 4-23
4.2.1 Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder (Preferred) 4-23
4.2.2 Cast-in-Place, Conventional Reinforced Concrete Box Girder. 4-23
4.2.3 Other Alternatives 4-23
4.3 Foundations 4-24
4.3.1 Bents 4-24
4.3.2 Abutments 4-24
4.4 Constructability 4-24
4.4.1 Falsework 4-24
4.4.2 Deep Foundations 4-24
4.4.3 MSE Wall "Island" 4-25
4.5 Barriers 4-25
4.6 Aesthetics 4-25
4.7 Cost Estimate 4-25
4.8 Recommendation 4-25
Chapter 5 US 101 Northbound On-Ramp Structure 5-1
5.1 Preferred Structure Type Summary 5-1
5.2 Structure Type Alternatives 5-2
5.2.1 Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder (Preferred) 5-2
5.2.2 Cast-in-Place, Conventional Reinforced Concrete Box Girder. 5-2
5.2.3 Other Alternatives 5-2
5.3 Foundations 5-3
5.3.1 Bents 5-3
5.3.2 Abutments 5-3
5.4 Constructability 5-3
5.4.1 Falsework 5-3
5.4.2 Deep Foundations 5-3
5.4.3 MSE Wall "Island" 5-4
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Appendices
5.5 Barriers..................
5.6 Aesthetics..............
5.7 Cost Estimate.........
5.8 Recommendation
5-4
5-4
5-4
5-4
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 4
Appendix A: 35% Bridge Plans
Appendix B: 35% Bridge Cost Estimates
Appendix C: Geometric Approval Drawings (GAD) Approval
Memo
Appendix D: Approved Bridge Site Data Submittal (BSDS)
Appendix E: Preliminary Bridge Design Hydraulic Study (BDHS) Appendix F: Draft Structure Preliminary Geotechnical Report (SPGR) Bridges
DRAFT
CHAPTER 1 GENERAL INFORMATION
Table 1-2 | Bridge Information and Cost
$26,392,000 New BridgeTBD
New BridgeTBD $19,057,000
New BridgeTBD $8,151,000
TBD New Bridge $9,427,000
PROJECT TOTAL (BRIDGE) $63,027,000
1.2 Introduction
Bridge Name Bridge Number Project Type Construction Cost Recommended Structure Type
POST MILES:
26.8/27.3
CO:
SLO
DIST:
05 RTE:
US 101
1.1 Structure Type Selection Summary
Table 1-1 | Project Identification
The project is located within Caltrans District 5 in the City of San Luis Obispo, San Luis Obispo County. The project area is located within Township 31 South, Range 12 East, on the U.S. Geological Survey (USGS) San Luis Obispo, California 7.5-minute quadrangle.
The U.S. Route 101 (US 101)/Prado Road Interchange Project (Prado Road Interchange) is being developed by the City of San Luis Obispo (City). The purpose of the project is to extend Prado Road over U.S. 101 to connect with Dalidio Drive and reconstruct the existing U.S. 101 northbound on- and off-ramp connections to Prado Road in order to provide congestion relief, operational efficiency, and multimodal connectivity.
The interchange is located in the City of San Luis Obispo on U.S. 101 PM 26.8. The project limits extend from PM 26.5 to PM 27.3.
PROJECT IDENTIFICATION:
US HWY 101/Prado Road Interchange Project
EA:
05-1H640
DATE:
July 2, 2026
Prado Road
West
Overcrossing
Prado Road
East
Overcrossing
US 101
Northbound
Off-Ramp
US 101
Northbound
On-Ramp
DESIGN GROUP:
Consor
PID:
0516000105
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 1-1
CIP/PT Reinforced
Concrete Box
Girder
CIP/PT Reinforced
Concrete Box
Girder
CIP/PT Reinforced
Concrete Box
Girder
CIP/PT Reinforced
Concrete Box
Girder
DRAFT
1.3 General Description
Morro Bay
Los Osos
22?
Arroyo Grande Grover Beach
R. in 5 Miles2.5
1 J
The PSR studied three alternatives for a full interchange:
San Luis
Obispo
Los Padres
National
k Forest
Figure 1-1 | Vicinity Map
A total of four (4) bridge structures is proposed as a part of the improvements for the Prado Road Interchange. The Prado Road Western Overcrossing and Eastern Overcrossing provide access across US 101, and the On-Ramp and Off-Ramp Structures provide access to and from US 101, respectively. This type selection report discusses the recommended structure types for each of these (4) bridge structures and summarizes their lengths and structure depths. The On-Ramp and Off-Ramp structures and a portion of the west overcrossing over US 101 are within Caltrans Right-of-way. The General Plans of these bridge structures are included in Appendix A.
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 1-2
1.4 Project History
The US 101/Prado Road Interchange is a project that has been discussed, studied, and developed since the early 1990's. Over time, the project plan has progressed from an overcrossing to a full interchange and from a full interchange to the current overcrossing with northbound ramps. One of the reasons for the overcrossing/interchange was the potential development of the Dalidio property on the west side of US 101 between Madonna Road and Los Osos Valley Road (LOVR). Throughout the years, the Dalidio development took on many forms and land uses with many starts and stops as is common for development.
The earliest planning document for the full interchange was a Project Study Report (PSR) prepared by Nolte and Associates for the City of San Luis Obispo and Caltrans in 1996. 0 L
DRAFT
> Tight diamond
> Spread diamond
> Spread diamond with a cloverleaf southbound off-ramp
Several key public service and transportation-related facilities are located along the Prado Road corridor and are relevant to the proposed project. These include the City's Water Resource Recovery Facility (WRRF), the 40 Prado Homeless Services Center, and the adjacent 46 Prado site. In addition, a nearby transit Because of interchange spacing issues with Madonna Road, a southbound collector-distributor roadway on the west side of US 101 to link Madonna Road and Prado Road was proposed to address the limited weaving distance on southbound US 101. At the time of the 1996 PSR, one of the primary drivers of the project, the Dalidio development to the west of the project, did not move forward and there was no support from Caltrans HQ to approve a design exception for the interchange spacing between Madonna and Prado.
Without developer funds to help offset construction costs and the Caltrans design exception hurdle, the Prado Interchange project laid dormant until the mid 2010's.
A 2018 Project Study Report/Project Development Support (PSR/PDS) noted that because of interchange spacing and forecast traffic needs, the 1996 solution of a full interchange with a collector-distributor was deemed invalid. Alternatives were advanced in the PSR/ PDS for the overcrossing and northbound ramps only. Subsequent traffic evaluations and the 2023 Traffic Operations Assessment Report (TOAR) amendment completed as part of the Project Approval and Environmental Document (PA&ED) supported designs for a refined overcrossing, northbound ramps, and a ramp terminal intersection. These recommendations are proposed to being advanced for final design and implementation.
In 2014, Coastal Community Builders (CCB) known as Ml San Luis Ranch, LLC, initiated an application to develop the Dalidio property. The San Luis Ranch development would include housing, affordable housing, recreation, retail, and commercial spaces with an emphasis on Farm to Table to honor the agricultural history of the property. With the development moving forward, the need for an overcrossing at Prado Road became necessary once again.
Prado Road, classified as a minor arterial according to the Caltrans California Road System (CRS) maps, is currently a two-lane facility that spans roughly one mile from its intersection with US 101. The area surrounding the project includes commercial uses northwest of the intersection of Prado Road and U.S. 101, commercial and residential uses northeast of said intersection.
1.5 Existing and Proposed Nearby Facilities
US 101 is the principal north/south freeway/expressway on the Central Coast traversing the counties of Santa Barbara, San Luis Obispo, Monterey and San Benito within District 5. It serves local, regional and interregional travel needs, including business, recreation, tourism, journey-to-work, freight and goods movement, and national defense transport and is part of the Pacific Coast Bicycle Route. Through the project area, US 101 is a four lane freeway with 12-foot through lanes, 5-foot inside shoulder, 10-foot outside shoulder and approximately 27-foot median. Right-of-Way width varies, but is generally 177 feet.
The nearest interchanges on either side of the project study area include Los Osos Valley Road located at PM 25.9 and Madonna Road located at PM 27.5. There is an existing northbound US 101 off-ramp to Prado Road and an existing Prado Road northbound on-ramp to US 101. The ramp connections to Prado Road are located at PM 26.8.
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The San Luis Ranch property is currently in the initial phases of development, with approved commercial, residential, recreational, and agricultural land uses under the San Luis Ranch Specific Plan, adopted by the City in 2017. There is a roundabout within this development at the intersection of Froom Ranch Way and Dalidio Drive that was constructed with the ability to incorporate an intersection with the future extension of Prado Road to the west US 101.
A preliminary Transportation Management Plan (TMP) Data Sheet/Checklist was previously prepared for this project and was included in the Project Report.
1.8 Staging Areas and Contractor Access
Access to the site is not anticipated to be limited due to its proximity to US 101 within San Luis Obispo.
Construction staging areas are anticipated to be located within the closed portion of Prado Road to the east of US 101 and the undeveloped area to the west of US 101.
On the eastern end of the Prado Road alignmentthe project abuts the western limits of the San Luis Obispo Creek Bridge Widening Project, which has independent utility from the proposed project and is currently being reviewed by the City of San Luis Obispo. This project includes widening the existing 2-lane bridge to provide a total of six lanes and a sidewalk on each side of the bridge.
The project also includes realignment of the Elks Lane intersection to accommodate the footprint of the proposed interchange improvements. The existing Elks Lane connection to Prado Road would be removed due to its conflict with the planned U.S. 101 northbound on- and off-ramp terminal intersection at Prado Road. To maintain local access and circulation, Elks Lane would be realigned to intersect Prado Road east of its current location, adjacent to the 40 Prado Homeless Services Center. operations facility serving local and regional bus services contributes to transit-related vehicle movements in the area.
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 1-4
1.6 Funding
It has been determined that this project is eligible for Federal-aid funding. The City plans to fund the project with a combination of impact fees, debt financing, and the SLOCOG Regional Transportation Improvement Program (RTIP). The PA&ED, PS&E, and Right-of-Way support phases are programmed with 100% local funds. The Construction phase has nearly $64 million currently programmed from a combination of RTIP and local funding sources. The City will continue to pursue additional funds through other state and federal grants.
1.7 Impacts to Traffic
For construction of the Prado Road Western Overcrossing, full freeway closures would be required for falsework erection and removal if the superstructure is constructed with the cast-in-place alternative. This may call for detours and/or median crossovers, which will be addressed in the PS&E phase. It will also need to be determined whether the current ramp configuration at Prado Road will remain open during construction, and if they can be used for the northbound detour. Southbound closure will be more complicated, possibly requiring use of a median crossover, or detour via Madonna Road and Los Osos Valley Road. Mainline closures of US 101 will be allowed at night only. A detour for Elks Lane will also need to be implemented during construction.
DRAFT
>
1.10.2 Scour
7 >
>
1.10 Hydraulic Considerations
The project is within the limits of the floodplain of San Luis Obispo Creek. Accordingly, HDR, Inc. (HDR) has provided a Preliminary Bridge Design Hydraulic Study (BDHS) for this project, and is included in Appendix E. The Preliminary BDHS was developed in accordance with Caltrans Structure Technical Policy (STP) 2.6, and includes:
1.9 Right of Way
An encroachment permit from Caltrans will need to be obtained for portions of the western overcrossing constructed within Caltrans right-of-way. Right-of-way acquisition will be required for portions of the western overcrossing to the west of US 101. Temporary construction easements may be required to establish sufficient area for construction staging areas.
Scour for both the 100-Year and 200-year flood events is evaluated in the Preliminary BDHS. The scour at each bridge support is summarized in the tables below.
1.10.1 Floodplain
All structures are located within the San Luis Obispo Creek Splitflow floodplain, which is categorized as a Zone AE Regulatory Floodway based on FEMA Flood Maps. The layout of the structures for this project was partly governed by the need to satisfy both FEMA and City requirements for allowable rises in water surface elevation in the floodplain between existing and proposed conditions. The analysis included in the Preliminary BDHS indicates that the proposed condition for this project results in a maximum change in water surface elevation of only 0.3 feet.
A review of available hydrologic data
Hydrologic analyses
Hydraulic analyses to determine design water surface elevations and flow velocities for existing and proposed conditions
Scour analyses to estimate potential scour depths for the proposed condition D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 1-5 Page 274 of 1065 DRAFT
Table 1-3 | 100-Year Flood Scour Values
1.4 4.7
US 101NB
Off-Ramp
Structure
US 101NB
Table 1-4 | 200-Year Flood Scour Values
7.7 .. ..
1.10.3 Drainage
Support
Support
Structure
Name
Structure
Name
Prado East
Overcrossing
Prado East
Overcrossing
Prado West
Overcrossing
Prado West
Overcrossing
Total Scour
Depth (ft)
Total Scour
Depth (ft)
Short Term
(Local) Scour
Depth (ft)
Short Term
(Local) Scour
Depth (ft)
US 101NB
Off Ramp
US 101NB
On Ramp
On-Ramp
Structure
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1.2 0
0.9 3.3
4.0 2.7
9.0 6.2
5.9 11.0
1.7 1.7
1.4 0.9
1.2 1.2
0.8 0.7
1.1 1.1
1.0 1.3
1.3 1.2
1.2 0
1.3 7.8
6.7 13
2.8 2.1
5.9 2.9
5.8 6.4
2.1 2.8
2.7 7.7
7.9 7.3
11.9 2.9
2.6 5.5
2.3 5.9
6.7 2.6
2.9 2.0
6.5 Caltrans Standard Plan type D-1 deck drains will be required for all the east and west overcrossings as well as the on and off Ramps. Deck drains will connect to City sewer systems where applicable or outlet into drainage swales for onsite treatment.
2.1 1.7
1.4 1.2
1.2 1.6
4.8 5.6
1.4 D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 1-6
9.9 8.4
14.4 4.0
3.3 7.0
3.9 7.1
1.1 1.2
1.7 2.0
5.6 Degradation
Scour Depth
(ft)
Contraction
Scour Depth
(ft)
Degradation
Scour Depth
(ft)
Contraction
Scour Depth
(ft)
Abut 1
Bent 2
Bent 3
Abut 4 (RW 9 Island)
Abut 1 (RW 9 Island)
Bent 2
Abut 3
Abut 1
Bent 2
Abut 3 (RW 9 Island)
Abut 1 (RW 9 Island)
Bent 2
Abut 3
Abut 1
Bent 2
Bent 3
Abut 4 (RW 9 Island)
Abut 1 (RW 9 Island)
Bent 2
Abut 3
Abut 1
Bent 2
Abut 3 (RW 9 Island)
Abut 1 (RW 9 Island)
Bent 2
Abut 3
DRAFT
1.11 Geotechnical Considerations
1.12 Seismic Ground Motion
1.4 1.2
/
1 08 1
0.4 0.2
1.0 2.0 3.0 6.0 7.0 8.0 9.0 10.0
ARS Online V4.0
--------- Design Response Spectrum
O Peak Ground Accleration = 0.39g
Figure 1-2 | Preliminary Design Response Spectrum
1.13 Liquefaction and Lateral Spreading Potential
Based on CPT soundings, potentially liquefiable medium dense layers of sand were encountered at depths of 44 to 55 feet below the ground surface. Liquefiable materials are not likely to impact roadways orsurface The seismic data for the project was generated by Yeh using selected site parameters and ARS Online version 4.0 to estimate ground motion parameters in accordance with Appendix B of the Caltrans Seismic Design Criteria (SDC) version 2.1, dated January 2025. Seismic data was generated for the Safety Evaluation Earthquake, which is defined as an earthquake with a 975-year return period. The shear wave velocity for the project site was estimated from the CPT data obtained by Yeh at the project site. The preliminary design response spectrum for the project is provided in Figure 1-2 below. For additional information, see the Draft SPGR prepared by Yeh included in Appendix F.
35.2569 degrees
-120.6748 degrees
320 meters/second
Mean Magnitude: 7.05 at 25.37 km
Spectral Damping. 5 percent
a 1
s
The Draft SPGR identifies cast-in-drilled-hole (CIDH) piles as generally the most suitable foundation support for each of the structures. The CIDH piles are recommended to be embedded below the compressible and liquefiable (if present) layers and bearing within the Francisan melange bedrock. The bedrock is located approximately 60 feet below the ground surface based on the available data. The Draft SPGR also identifies that both driven and cast-in-steel-shell (CISS) piles are considered feasible alternatives for this site.
Yeh and Associates, Inc. (Yeh) has prepared a Draft Structure Preliminary Geotechnical Report (SPGR) for the bridge structures included in this project and is included in Appendix F. The Draft SPGR includes a discussion of project alternatives, site conditions, geologic conditions, seismicity and faulting, geotechnical considerations regarding the overcrossings and ramp structures foundation alternatives, and additional field and laboratory data needed for design. The preliminary characterization of the subsurface conditions is based on boring information from previous explorations performed in the vicinity of the project site as well as cone penetration test (CPT) soundings performed for Phase 1 of this project. —V •V
\
0 —
0.0 Latitude:
Longitude:
V,20:
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 1-7
4.0 5.0
Period, T (sec)
8 r
DRAFT
1.14 Horizontal Layout
Table 1-5 | Roadway Typical Sections
N/A2-11' Lanes
1.15 Vertical Profile
Structure Travel Lanes Shoulders Sidewalk
The vertical profiles were also developed to meet the freeboard requirements listed in the Caltrans Structure Technical Policy (STP) 2.6. STP 2.6 indicates that the soffit of each of the structures must provide at least 2-feet of freeboard over the 50-year flood and at least convey the 100-year flood with no freeboard. 2-12' Lanes and 1-11'
Median/Turning Lane
improvements, but could have an impact on deep foundations for the project. Additional subsurface explorations will be required to verify if there are liquefiable layers and if it will be a design constraint.
The horizontal alignment and typical section of each of the structures are governed by the roadway design criteria that was agreed upon in conjunction with the City and Caltrans considering the volume of traffic and design speed. The design criteria for both Prado Road and the On & Off-Ramps are included in the "Design Criteria Memorandum" prepared for this project by Consor. The typical section geometry parameters are summarized for each structure in the table below.
The vertical profile of each of the structures is primarily governed by the required vertical clearance between the soffit of the Prado Road West Overcrossing and the existing profile of US 101. Section 309.2 of the Caltrans HDM indicates that a minimum of 16.5-feet of vertical clearance must be provided for structures spanning over highways.
The layout of the abutments and intermediate bents of the western overcrossing are governed by the minimum horizontal clearance required by Section 309.1 of the Caltrans Highway Design Manual (HDM).
The Caltrans HDM requires that supports be located a minimum of 20-feet beyond each edge of travel way for US 101.
Liquefaction-induced lateral spreading is not a consideration for the design of the overcrossings and ramp structures based on review of previous data collected at the site and the CPT soundings performed for this project.
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 1-8
Note:
1. Southernmost eastbound lane width transitions from 0' to 11' on the eastern overcrossing.
2. Travel lane width is roughly 16-feet minimum on the on-ramp structure.
Prado Road Western
Overcrossing
Prado Road Eastern
Overcrossing
US 101 On-Ramp
Structure
US 101 Off-Ramp
Structure
Left EOD - 6' Sidewalk
minimum & varies
Right EOD - 14' Sidewalk
minimum & varies
Left EOD - 6' Sidewalk
Right EOD - 14' Sidewalk
N/A
Left EOD - 4' minimum &
varies
Right EOD - 4'
Left EOD - 5'
Right EOD-5'
Left EOD - 4' minimum &
varies
Right EOD -8' minimum
& varies
Left EOD - 4'
Right EOD - 8'
l- Lane, 3-11' Lanes1,
and 1-11' Median
1-12' Lane minimum &
varies2
DRAFT
1.15.1 Falsework
1.16 Structure Layout
Top of Barrier Superstructure
3 2
>5’-0”
V
[ nMSE
FG
A%
The Consor team has since performed more detailed
hydrologic and hydraulic analyses of the floodplain to
aid in the preparation of the Preliminary BDHS.
Iterations of these analyses were performed to
determine the most cost-efficient structure layout that still meets the requirements for impacts to the
floodplain. It was determined that reducing the total
length of the overcrossing to 750 feet would be
acceptable through these iterations of the analyses.
This led to converting the easternmost span of the
overcrossing to a bridge approach supported by MSE
walls, and more notably implementing an "island" of
MSE wall at the structure intersection directly east of US 101. The proposed island support will be composed of
a Mechanically Stabilized Embankment Abutment
(MSEA) Type 2 (per Caltrans Memos to Designers 5-1)
that spans the entire perimeter of this intersection and is offset to provide a minimum clearance between
the front of the MSE wall and the abutment of
each of the four structures. The implementation
of the MSEA Type 2 splits the overcrossing into
The alignments of the overcrossing, on-ramp, and off-ramp structures intersect directly adjacent to US 101 on its east side. Previous studies of the floodplain for this project had determined that the overcrossing would have needed to span approximately 1050 feet between the west and east approaches in order to limit water surface elevation impacts to an acceptable amount. This would have required the ends of the on-ramp and off-ramp superstructures to directly connect to a span of the overcrossing, which would lead to nonstandard detailing and construction methods, more unpredictable seismic performance, and increases in construction cost.
two separate structures, western and eastern, and provides cost savings and more predictable seismic performance compared to the previously proposed elevated intersection. The cost savings are primarily associated with the reduction in retained height of the abutments, reducing vertical and overturning loads on the deep foundations. Further discussion of the island support is included in the separate Type Selection Report developed for the retaining walls for this project.
In addition to the clearance requirements over US 101 for the permanent condition, there are temporary clearance requirements that the vertical profile of the western overcrossing would need to meet if falsework is required for construction. Falsework would be required if cast-in-place construction methods are used for the construction of the superstructure for the western overcrossing. Section 204.8 of the Caltrans HDM requires that a minimum vertical falsework clearance over US 101 of 15 feet must be provided. It should be evaluated for a cast-in-place superstructure alternative if this required temporary vertical clearance, considering the anticipated depth of falsework for the minimum falsework span lengths over US 101, can be feasibly provided.
o
N
A |
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 1-9
Figure 1-3 | MSEA Type 2 Diagram (MTD 5-1)
DRAFT
>
>
>
>
1.18.1 Corrosion
1.18.2 Scour
1.18 Design Criteria
The design criteria for the bridge structures are primarily based on the codes and guidelines below. See the Design Criteria Memorandum for the Road and Bridge, both included in the Appendix, for further information.
In accordance with Caltrans STP 2.6, the bridge design will consider scour for the 100-year flood event (Scour Design Flood) along with scour for the 200-year flood event (Scour Check Flood) for the Extreme II limit state. The bottom of the pile caps for the abutments will be located below the total scour elevation for the Scour Design Flood with the exception of abutments supported by the MSEA Type II wall.
1.17 Design Exceptions
No design exceptions related to the bridge design are currently anticipated for this project.
In accordance with guidance provided by Tony Nedwick with Caltrans Structures Hydraulics, the pile caps for the abutments at the MSEA Type II wall do not need to be located below the total scour elevation of the Scour Design Flood as long as the abutment piles are designed to be stable under scoured conditions while neglecting any support of the MSEA Type II wall. The piles for the four abutments located at the MSEAType II wall will be designed accordingly.
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 1-10
The Draft SPGR indicates that the soils at the site are not corrosive. Standard concrete cover and conventional uncoated reinforcement details will be used for the design. Freeze thaw is not a concern at this site.
Road Design
Roadway design will be based on AASHTO "Guidelines for Geometric Design of Low-Volume Roads 2019 (2nd Edition)" (GDLVR) supplemented with AASHTO "A Policy on Geometric Design of Highways and Streets 2018 (7th Edition)" (Green Book), and County Public Improvement Standards 2022 where applicable.
Bridge Design
Bridge design will be performed in accordance with "AASHTO LRFD Bridge Design Specifications (8th Edition)", and the "Caltrans Amendments (dated April 2019)". The latest versions of the Caltrans bridge design manuals, Bridge Design Memos (BDMs), and Structure Technical Policies (STPs) at the time of type selection will also be utilized in the design.
Seismic Design
Seismic design will be performed in accordance with the Caltrans "Seismic Design Criteria Version 2.1 (February 2025)" and the latest information available from Caltrans Earthquake Research. All bridge structures will be categorized as "Ordinary Standard" bridges.
Hydraulic Design
The hydraulics design will be in accordance with Caltrans STP 2.6 "Hydraulic Design for Structures over Waterways". The proposed bridge soffit will be located a minimum of 2 feet above the 50-year flood elevation, or convey the 100-year flood (i.e., no freeboard), whichever is greater.
DRAFT
1.19 Utilities
1.20 General Aesthetics
1.22 Environmental Studies and Permits
Table 1-6 | Permits
Regional Water Quality Control Board (RWQCB) Clean Water Act (CWA) § 401 California Department of Fish and Wildlife (CDFW) Streambed Alteration Agreement 1600 Resource Agency Permit
SWCA, Inc. will conduct and prepare the technical studies, prepare the California Environmental Quality Act (CEQA) document, and prepare project permit applications.
The County will be the lead agency for CEQA, and the anticipated document will be an Initial Study Mitigated Negative Declaration (IS/MND). Caltrans will be the lead agency for the National Environmental Policy Act (NEPA), and the anticipated document will be a Categorical Exclusion (CE). The project is not expected to result in any negative impacts to native plant or animal species. SWCA will prepare permit applications after environmental clearance is obtained shown below. Note the City will be responsible for obtaining an encroachment permit from Caltrans for all work within Caltrans right-of-way.
Consor and Apexx Architecture, LCC (Apexx), a subconsultant, are in the process of developing preliminary concepts for the overall aesthetics for the project. These preliminary concepts are being developed with the goal of achieving consensus for the direction of the overall aesthetics of the project with all stakeholders involved, including the City and Caltrans, while maintaining consistency with the requirements of the Visual Impact Assessment for the project. Structural elements of the bridge structures that may receive architectural treatment for developing the aesthetics of the project potentially include the barriers, railing, lighting, columns, bent caps, and other elements.
1.21 Approach Slabs
Structure Approach Type N (30) approach slabs per the Caltrans Standard Plans will be implemented at all bridge approaches in accordance with Caltrans STP 2.2.
It is anticipated that the only utilities that will be carried on the bridge structures will be smaller dry utilities (6 inch diameter maximum) located within the sidewalks on the overcrossings.
Various utilities located within the vicinity of the project site will either be relocated or remain in place during construction. Among these utilities is an oil line owned by Phillips 66, which will be relocated with sufficient clearance away from the US 101 NB Off-Ramp and Prado Road Eastern Overcrossing foundations.
Two proposed water lines, each owned by the City and 12 inch in diameter, will be located underground along Prado Road.
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CHAPTER 2 PRADO ROAD WEST OVERCROSSING
2.1 Preferred Structure Type Summary
Table 2-1 | Structure Summary — Prado Road Western Overcrossing Bridge Name Prado Road West Overcrossing over US 101
Bents
Vertical Clearance
Approaches
Deck Protection
Drains
Loading
Profile
Abutments
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 2-12
Temp Vertical Clearance
Barriers/Sidewalks
Temperature Range
Joints
Utilities
Bridge Number
Structure Type
Structure Cost
Spans
Structure Depth
Depth-to-Span Ratio
Structure Width
Future Widening
Aesthetics
TBD
Cast-In-Place, Post-Tensioned Reinforced Concrete Box Girder $26,392,000
Span 1-3 = 150-0"; Total Length = 450-0"
6'-0"
Spans 1-3: 0.040
65'-4" minimum total width and varies starting at Bent 3 to 89'-10" maximum total width at Abut 4, including:
■ 2-12'-0" Lanes
■ 1-1T-0" Median/Turning Lane
■ l-4'-0" Minimum & Varies Shoulder at LEOD
■ l-4'-0" Shoulder at REOD
■ 6'-0" Minimum & Varies Sidewalk at LEOD
■ 14'-0" Minimum & Varies Sidewalk at REOD
Crowned at "P" Line with 2% cross slope each direction
Abut 1: Seat Type Abutment on Three Rows of HP14x89 Piles Abut 4: Seat Type Abutment on Two Rows of HP14x89 Piles Bent 2 & 3: Integral bent cap with a single row of 3 - 5'-0" diameter columns pinned top founded on 7'-0" diameter Type II CIDH piles
16'-6" minimum is met over US 101
2'-0" minimum freeboard over 50-year WSE and 0' minimum freeboard over 100- year WSE is met over full length
15'-0" minimum is met over US 101 for falsework
LEOD: Type 732SW barrier sidewalk width = 6'-0"
REOD: Type 732SW barrier sidewalk width = 14'-0"
Abutment 1: Structure Approach Type N (30)
Abutment 4: Structure Approach Type N (Mod)
This structure is in a Non-Freeze-Thaw Area, in which deck salting does not occur.
No special deck protection is required.
Deck Drainage will be required. Drain location and layout are pending.
Interdisciplinary coordination will be required to determine viability of drainage pipe to storm drain connections at columns and abutments.
10°F to 80°F
Abutment 1 & 4: Type B Joint Seal (MR = 2")
Anticipated lighting and PG&E electrical conduits will be carried by the overcrossing. 6" diameter maximum located inside REOD barrier sidewalk.
Live Load (LL): HL93 and permit design load
Dead Load (DC): Type 732SW barriers and railing
Additional Dead Load (DW): 35 psf for future wearing surface; 100 plf allowance for utilities
None.
TBD
DRAFT
2.2 Structure Type Alternatives
2.2.3 Other Alternatives
Alternatives analysis focused more on commonly economical structure types for the required span configuration. Other cast-in-place and precast alternatives structure types were not considered
2.2.2 Precast, Pretensioned Reinforced Concrete California Wide Flange Grider
This structure type results in the lowest construction cost and provides visual consistency with other structures within this section of the corridor, such as the LOVR overcrossing. The ability to form the superstructure on-site also provides the advantage of increased constructability and design compatibility with accommodating the horizontal curve on the overcrossing on the western portion. Additionally, a flare in the width of the superstructure near the ramp intersection is required to accommodate an acceptable truck turn radius and an acceptable sight distance, which can be easily incorporated with cast-in-place construction. The primary disadvantage of this alternative includes requiring falsework, creating the need for night closures for its installation and longer construction duration. However, temporary night closures are considered feasible, and the construction duration is not critical forthis project. Additionally, the profile of the overcrossing for this alternative would need to consider accommodating a minimum temporary vertical clearance of 15 feet for the falsework over US 101.
The proposed structure type is a three-span cast-in-place, post-tensioned reinforced concrete box girder supported by seat type abutments founded on multiple rows of driven steel H-piles and bents supported by a single row of columns founded on Type II Cast-in-Drilled-Hole (CIDH) shafts. The structure depth would be 6 feet total with a total width of 65 feet 4 inches minimum and varies within Span 3 to a maximum width of 89'-10" at Abutment 4.
Precast alternatives are not typically economical compared to cast-in-place alternatives and are usually only used when falsework installation is not possible or there is a desire to reduce construction duration.
Additionally, the horizontal curve on the western end of the bridge would require a more complicated design and more complicated formwork between the girders compared to a cast-in-place alternative. This alternative is considered a feasible, but not preferred alternative for these reasons. This alternative could be considered preferred if the required falsework configuration for the cast-in-place alternative is not feasible or if the aesthetics of the precast girder are desired.
Due to its span length, a precast alternative would need to include the utilization of California Wide Flange Girders. These girders would be 72 inches deep and support a cast-in-place reinforced concrete topping slab, resulting in a total structure depth of 7 feet. A total of eight girders spaced at approximately 8.25 feet are anticipated to be required to support the full width structure of 65 feet 4 inches. The abutments would be seat type abutments founded on multiple rows of driven steel H-piles and the bents would be a drop bent cap supported on a single row of columns founded on Type II CIDH shafts. accordingly. A steel superstructure was also not considered due to typically higher construction costs and increased maintenance needs compared to a concrete superstructure.
2.2.1 Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder (Preferred)
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2.3 Foundations
2.3.1 Bents
2.3.2 Abutments
2.4 Constructability
2.4.1 Falsework
The primary constructability consideration for the preferred alternative is the feasibility of the installation of falsework at this site. The falsework will need to span over each of the northbound and southbound corridors of US 101, which are both composed of two 12-foot lanes, one 5-foot shoulder, and one 10-foot shoulder for a total minimum normal width of traffic opening of 39 feet. Based on the guidance provide in Table 204.8 of the Caltrans HDM, this width would result in a resulting falsework span of up to 51 feet and a minimum falsework depth of 3-foot 1-inch. This guidance is based on the assumption that temporary barriers will be installed at each edge of shoulder that are anchored. The proposed profile of Prado Road and superstructure depth of the overcrossing for the cast-in-place alternative would be in accordance with the minimum vertical clearance requirement of 15 feet based on these assumptions.
A variable depth box girder bridge with a parabolic soffit could be considered for this site if desired. The maximum depth at the bents would be approximately 6-foot 9-inch and the minimum depth at midspan of the intermediate span and near the abutment of the end spans would be approximately 4-foot 6-inch.
Disadvantages of this alternative would include inconsistent visual appearance with other nearby structures located within this section of the US 101 corridor, and potentially requiring a raise in profile grade to accommodate the greater structure depth at the intermediate supports. Additionally, even though providing a parabolic flare in the soffit typically reduces the total material required for the construction of the superstructure, it could potentially result in a minor increase in construction costs due to the increase in complexity of the formwork.
Driven steel H-piles are utilized instead of CIDH piles at the abutments. The driven piles are more costeffective than CIDH piles for the abutments because they do not need to be embedded deep into the relatively weak top of bedrock layer. Driven piles are more feasible at the abutment supports because the excavation required for constructing the pile cap is not considered an issue at the abutments, unlike the bent locations that are near US 101. Three rows of HP14x89 piles are anticipated at Abutment 1 to sufficiently resist the lateral load demands of a relatively tall abutment, while only two rows of HP14x89 piles are anticipated to be required at Abutment 4 due to the reduction in abutment height that the MSE "island" provides. Analysis of the lateral stability of the proposed pile layout will be performed after borings are completed for this project.
Type II CIDH shafts are utilized for the bent supports because they are identified as the preferred pile type in the Draft SPGR due to their constructability, cost-effectiveness, and lateral capacity. 7-foot diameter Type II CIDH shafts were selected to support the 5-foot diameter columns required by Caltrans SDC requirements. The Draft SPGR recommends that the CIDH piles be embedded into the Franciscan melange bedrock layer to achieve vertical capacity, which could be as low as 60-feet below the existing ground surface. The Draft SPGR also provides a figure that displays the required embedment into bedrock corresponding to the preliminary factored nominal resistance for various sizes of CIDH piles, which indicates that the vertical tip of a 7-foot diameter Type II pile would be roughly 120 feet below the existing ground surface.
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4 ...
14 x te
seryre
SaEs - — to
Figure 2-1 | US 101 Median (looking northbound)
The following constructability considerations were also provided in the Draft SPGR for driven piles:
d
12 i 4
Lite elc
The piles for the abutment support at the MSE wall "island" fully provide vertical support for the bridge, while the MSE wall will help provide lateral resistance to the piles. The sequencing and methodology of constructing each of the MSE wall and the deep foundations for the abutment must be considered accordingly. Simple cutting and bending of the reinforcements for the MSE wall for installation of the piles is not recommended to be allowed. It is anticipated that a casing can be provided around each pile to ensure that an adequate area within the reinforced region for the wall is provided for each pile. The casing would then be filled with sand prior to constructing the pile cap so that the lateral resistance of the piles are not isolated from the MSE wall. Methodology for designing and installing the MSE wall reinforcement The erection and removal of the falsework will require night closures of US 101. It will be assessed if detour routes and/or median crossovers are required during the PS&E phase. Additionally, there is an existing stretch of guardrail present in the middle of the median between the northbound and southbound corridors that could potentially conflict with a falsework support. Either the minimum normal width of traffic opening could be reduced, or a section of the existing guardrail could be removed if required for the installation of the falsework support(s) in the median.
2.4.2 Deep Foundations
The Draft SPGR indicates that wet methods (slurry displacement) will likely be needed to construct the CIDH piles because of the groundwater elevation encountered in the previous borings at the project site.
Temporary casings could also be necessary to support the shaft during drilling and advancing the hole through soft ground, caving soil layers, and groundwater.
SCR
Hard driving conditions could be associated with the denser layers of older alluvium or within the Franciscan melange bedrock. The bedrock may also have variable depths and variable driving conditions based on the presence of harder, more resistant blocks within the formation. Predrilling for pile installation could be necessary to penetrate into the bedrock to achieve the needed axial and lateral resistances.
Pile driving could be delayed if splicing of steel piles is needed if field conditions vary from observed conditions.
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 2-15
■
0 2.4.3 MSE Wall “Island”
» f r.
DRAFT
2.5 Barriers
2.6 Aesthetics
2.7 Cost Estimate
Alternative 1 - Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder Total Structure Construction Cost = $26,392,000o
Alternative 2 - Precast, Prestressed Reinforced Concrete California Wide Flange Girder Total Structure Construction Cost = $27,649,000o
2.8 Recommendation
Both edges of deck will support Caltrans Standard Plan Type 732SW concrete barriers. The Type 732SW barrier on the north side (left edge of deck) will provide a 6-foot wide sidewalk, which is in conformance with the minimum width provide in the standard plan. The Type 732SW barrier on the south side (right edge of deck) will provide a total 14-foot wide sidewalk to incorporate a Class I Bikeway in accordance with the Caltrans HDM.
around these vertical obstructions is discussed in Section 5.4.2 of the FHWA GEC Oil and the Type Selection Report for the retaining walls.
General Plan Estimates for both alternatives were prepared utilizing unit costs determined from available Caltrans Contract Cost Data and from bid results for previous projects. A 10% mobilization, a 25% contingency, and a 6.19% escalation rate were added to the subtotal of construction costs. The estimated cost for both alternatives is shown below:
A standard one-way flare at the top of the columns at each bent. The flare would be architectural only, with a horizontal gap provided between the top of the column and the superstructure beyond the structural section.
Black paint coating incorporated for the tubular handrailing and chain link railing installed on top of the Type 732SW barriers, for both the desired appearance and to help protect the railing from corrosion.
Aesthetics are anticipated to be proposed for the western overcrossing, but options are still being evaluated. Typical treatments that could be implemented include:
Alternative 1 - Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder is the preferred alternative because it provides the most cost-effective solution for this site. Alternative 2 is also feasible and could be considered further if the installation of falsework in the median of US 101 is infeasible and if the appearance of the precast girders is desired. Additionally, the incorporation of a variable depth superstructure could be further considered if its appearance would be desired.
The Type 732SW concrete barriers will support tubular handrailing on Span 1 and Span 2, while Chain Link Railing Type 7 will be supported by the barriers on Span 3 that spans over US 101. Both the handrailing and the chain link railing will be in accordance with the Caltrans Standard Plans. Lighting is also proposed to be installed on the overcrossing.
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CHAPTER 3 PRADO ROAD EAST OVERCROSSING
3.1 Preferred Structure Type Summary
Table 3-1 | Structure Summary — Prado Road Eastern Overcrossing Bridge Name Prado Road East Overcrossing over US 101
Bents
Vertical Clearance
Approaches
Deck Protection
Drains
Loading
Profile
Abutments
Temp Vertical Clearance
Barriers/Sidewalks
Temperature Range
Joints
Utilities
Bridge Number
Structure Type
Structure Cost
Spans
Structure Depth
Depth-to-Span Ratio
Structure Width
Future Widening
Aesthetics
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 3-17
TBD
Cast-In-Place, Post-Tensioned Reinforced Concrete Box Girder $19,057,000
Span 1-2 = 150-0"; Total Length = 300-0"
6'-0"
Spans 1-2: 0.040
77'-10" minimum total width at Abut l & varies to 87'-4" maximum total width at Abut 3, including:
■ l-12'-0" Lane
■ 3-ll'-0" Lanes (Southern eastbound lane width transitions from 0' to 11') ■ 1-11-0" Median
■ l-4'-0" Shoulder at LEOD
■ l-5'-0" Shoulder at REOD
■ 6'-0" Sidewalk at LEOD
■ 14'-0" Sidewalk at REOD
Crowned at "P" Line with 2% cross slope each direction
Abut 1: Seat Type Abutment on Two Rows of HP14x89 Piles Abut 3: Seat Type Abutment on Two Rows of HP14x89 Piles Bent 2: Integral bent cap with a single row of 4 - 5'-0" diameter columns pinned top founded on 7'-0" diameter Type II CIDH piles
2'-0" minimum freeboard over 50-year WSE and 0' minimum freeboard over 100- year WSE is met over full length
N/A
LEOD: Type 732SW barrier sidewalk width = 6'-0"
REOD: Type 732SW barrier sidewalk width = 14'-0"
Abutment 1: Structure Approach Type N (Mod)
Abutment 3: Structure Approach Type N (30)
This structure is in a Non-Freeze-Thaw Area, in which deck salting does not occur.
No special deck protection is required.
Deck Drainage will be required. Drain location and layout are pending.
Interdisciplinary coordination will be required to determine viability of drainage pipe to storm drain connections at columns and abutments.
10° to 80°
Abutment 1 & 3: Type B Joint Seal (MR = 2")
Anticipated lighting and PG&E electrical conduits will be carried by the overcrossing. 6" diameter maximum located inside REOD barrier sidewalk.
Live Load (LL): HL93 and permit design load
Dead Load (DC): Type 732SW barriers and railing
Additional Dead Load (DW): 35 psf for future wearing surface; 100 plf allowance for utilities
None.
TBD
DRAFT
3.2 Structure Type Alternatives
3.2.3 Other Alternatives
Alternatives analysis focused more on commonly economical structure types for the required span configuration. Other cast-in-place and precast alternatives structure types were not considered A variable depth box girder bridge with a parabolic soffit could be considered for this site if desired. Even though providing a parabolic flare in the soffit typically reduces the total material required for the construction of the superstructure, it could potentially result in a minor increase in construction costs due to the increase in complexity of the formwork. This alternative is not considered preferred for the eastern
3.2.2 Precast, Pretensioned Reinforced Concrete California Wide Flange Grider
This structure type results in the lowest construction cost and provides visual consistency with the on- and off-ramp structures. The ability to form the superstructure on-site provides the advantage of increased constructability and design compatibility with accommodating the varying width of the overcrossing. The primary disadvantage of this alternative is that the duration required to erect and remove falsework and for the superstructure to cure would correlate with an overall longer construction duration compared to other alternatives. However, the construction duration of this structure is not critical for this project.
Additionally, there is no minimum temporary vertical clearance requirementforthis project because it does not cross over the freeway.
Precast alternatives are not typically economical compared to cast-in-place alternatives and are usually only used when falsework installation is not possible or there is a desire to reduce construction duration.
Additionally, the varying width of the overcrossing would require a more complicated design and more complicated formwork between the girders compared to a cast-in-place alternative. This alternative is considered a feasible, but not preferred alternative for these reasons. This alternative could be considered further if reducing the construction duration or if the aesthetics of the precast girder are desired.
3.2.1 Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder (Preferred)
The proposed structure type is a two-span cast-in-place, post-tensioned reinforced concrete box girder supported by seat type abutments founded on multiple rows of driven steel H-piles and a bent supported by single row of columns founded on Type II Cast-in-Drilled-Hole (CIDH) shafts. The structure depth would be 6 feet total with a total width varying between 77-feet 10-inches and 87-feet 4-inches.
Due to its span length, a precast alternative would need to include the utilization of California Wide Flange Girders. These girders would be 72 inches deep and support a cast-in-place reinforced concrete topping slab, resulting in a total structure depth of 7 feet. A total of eleven girders with varied spacing at each support are anticipated to be required to support the varied width structure. The abutments would be seat type abutments founded on multiple rows of driven steel H-piles and the bent would be a drop bent cap supported on a single row of columns founded on Type II CIDH shafts. accordingly. A steel superstructure was also not considered due to typically higher construction costs and increased maintenance needs compared to a concrete superstructure.
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3.3 Foundations
3.3.1 Bents
3.3.2 Abutments
3.4 Constructability
3.4.1 Falsework
The following constructability considerations were also provided in the Draft SPGR for driven piles:
Hard driving conditions could be associated with the denser layers of older alluvium or within the Franciscan melange bedrock. The bedrock may also have variable depths and variable driving conditions based on the presence of harder, more resistant blocks within the formation. Pre3.4.2 Deep Foundations The Draft SPGR indicates that wet methods (slurry displacement) will likely be needed to construct the CIDH piles because of the groundwater elevation encountered in the previous borings at the project site.
Temporary casings could also be necessary to support the shaft during drilling and advancing the hole through soft ground, caving soil layers, and groundwater.
The erection and removal of falsework will be required for the construction of the preferred structure. The installation of falsework is not a constructability concern because the eastern overcrossing does not cross over an open portion of road or freeway.
Driven steel H-piles are utilized instead of CIDH piles at the abutments. The driven piles are more costeffective than CIDH piles for the abutments because they do not need to be embedded deep into the relatively weak top of bedrock layer. Driven piles are more feasible at the abutment supports because the excavation required for constructing the pile cap is not considered an issue at the abutments, unlike the bent locations that are near US 101. Two rows of HP14x89 piles are anticipated at Abutment 3 to sufficiently resist the lateral load demands for a relatively short abutment, while two rows of HP14x89 piles are anticipated to be required at Abutment I as well due to the reduction in abutment height that the MSE "island" provides. Analysis of the lateral stability of the proposed pile layout will be performed after borings are completed for this project.
Type II CIDH shafts are utilized for the bent supports because they are identified as the preferred pile type in the Draft SPGR due to their constructability, cost-effectiveness, and lateral capacity. 7-foot diameter Type II CIDH shafts were selected to support the 5-foot diameter columns required by Caltrans SDC requirements. The Draft SPGR recommends that the CIDH piles be embedded into the Franciscan melange bedrock layer to achieve vertical capacity, which could be as low as 60-feet below the existing ground surface. The Draft SPGR also provides a figure that displays the required embedment into bedrock corresponding to the preliminary factored nominal resistance for various sizes of CIDH piles, which indicates that the vertical tip of a 7-foot diameter Type II pile would be roughly 120 feet below the existing ground surface.
overcrossing because the level of visibility of this structure is anticipated to be lower than the western overcrossing.
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 3-19 Page 288 of 1065 DRAFT
3.5 Barriers
3.6 Aesthetics
3.7 Cost Estimate
Alternative 1 - Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder Total Structure Construction Cost = $19,057,000o
Alternative 2 - Precast, Prestressed Reinforced Concrete California Wide Flange Girder The piles for the abutment support at the MSE wall "island" fully provide vertical support for the bridge, while the MSE wall will help provide lateral resistance to the piles. The sequencing and methodology of constructing each of the MSE wall and the deep foundations for the abutment must be considered accordingly. Simple cutting and bending of the reinforcements for the MSE wall for installation of the piles is not recommended to be allowed. It is anticipated that a casing can be provided around each pile to ensure that an adequate area within the reinforced region for the wall is provided for each pile. The casing would then be filled with sand prior to constructing the pile cap so that the lateral resistance of the piles are not isolated from the MSE wall. Methodology for designing and installing the MSE wall reinforcement around these vertical obstructions is discussed in Section 5.4.2 of the FHWA GEC Oil and the Type Selection Report for the retaining walls.
Both edges of deck will support Caltrans Standard Plan Type 732SW concrete barriers. The Type 732SW barrier on the north side (left edge of deck) will provide a 6-foot wide sidewalk, which is in conformance with the minimum width provide in the standard plan. The Type 732SW barrier on the south side (right edge of deck) will provide a total 14-foot wide sidewalk to incorporate a Class I Bikeway in accordance with the Caltrans HDM.
General Plan Estimates for both alternatives were prepared utilizing unit costs determined from available Caltrans Contract Cost Data and from bid results for previous projects. A 10% mobilization, a 25% contingency, and a 6.19% escalation rate were added to the subtotal of construction costs. The estimated cost for both alternatives is shown below:
Aesthetics are anticipated to be proposed for the eastern overcrossing, but options are still being evaluated. Typical treatments that could be implemented include:
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 3-20
A standard one-way flare at the top of the columns at each bent. The flare would be architectural only, with a horizontal gap provided between the top of the column and the superstructure beyond the structural section.
Black paint coating incorporated for the tubular handrailing installed on top of the Type 732SW barriers, for both the desired appearance and to help protect the railing from corrosion.
The Type 732SW concrete barriers will support tubular handrailing that will be in accordance with the Caltrans Standard Plans. Lighting is also proposed to be installed on the overcrossing. drilling for pile installation could be necessary to penetrate into the bedrock to achieve the needed axial and lateral resistances.
Pile driving could be delayed if splicing of steel piles is needed if field conditions vary from observed conditions.
3.4.3 MSE Wall “Island”
DRAFT
Total Structure Construction Cost = $20,287,000o
3.8 Recommendation
Alternative 1 - Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder is the preferred alternative because it provides the most cost-effective solution for this site. Alternative 2 is also feasible and could be considered further if reduction in construction duration and/or if the appearance of the precast girders is desired.
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 3-21 Page 290 of 1065 DRAFT
CHAPTER 4 US 101 NORTHBOUND OFF-RAMP STRUCTURE
4.1 Preferred Structure Type Summary
Table 4-1 | Structure Summary - US 101 NB Off-Ramp
Bridge Name US 101 NB Off-Ramp
Bents
Vertical Clearance
Approaches
Deck Protection
Drains
TBD
Profile
Abutments
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 4-22
Temperature Range
Joints
Utilities
Loading
Future Widening
Aesthetics
Bridge Number
Structure Type
Structure Cost
Spans
Structure Depth
Depth-to-Span Ratio
Structure Width
Temporary Vertical
Clearance
Barriers/Sidewalks LEOD: Type 836 Concrete Barrier
REOD: Type 836 Concrete Barrier
Abutment 1: Structure Approach Type N (30)
Abutment 3: Structure Approach Type N (Mod)
This structure is in a Non-Freeze-Thaw Area, in which deck salting does not occur. No special deck protection is required.
Deck Drainage will be required. Drain location and layout are pending.
Interdisciplinary coordination will be required to determine viability of drainage pipe to storm drain connections at columns and abutments.
10° to 80°
Abutment 1 & 3: Type B Joint Seal (MR = 2")
None.
Live Load (LL): HL93 and permit design load
Dead Load (DC): Type 836 barriers and railing
Additional Dead Load (DW): 35 psf for future wearing surface None.
TBD
Cast-In-Place, Post-Tensioned Reinforced Concrete Box Girder $8,151,000
Span 1-2 = 125'-0"; Total Length = 250-0"
5'-0"
Spans 1-2: 0.040
39'-6" total width including:
■ 2-12'-0" Lanes
■ 4'-0" Shoulder at LEOD
■ 8'-0" Shoulder at REOD
Superelevated, with a superelevation transition across its length Abut 1: Seat Type Abutment on Three Rows of HP14x89 Piles Abut 3: Seat Type Abutment on Two Rows of HP14x89 Piles Bent 2: Integral bent cap with a single row of 2 - 4'-0" diameter columns pinned top founded on 6'-0" diameter Type II CIDH piles
2'-0" minimum freeboard over 50-year WSE and 0' minimum freeboard over 100- year WSE is met over full length
None.
DRAFT
4.2 Structure Type Alternatives
This structure type results in the lowest construction cost and provides visual consistency with the overcrossing. The ability to form the superstructure on-site provides the advantage of increased
4.2.2 Cast-in-Place, Conventional Reinforced Concrete Box Girder
4.2.3 Other Alternatives
A variable depth box girder bridge with a parabolic soffit could be considered for this site if desired. Even though providing a parabolic flare in the soffit typically reduces the total material required for the construction of the superstructure, it could potentially result in a minor increase in construction costs due to the increase in complexity of the formwork. This alternative is not considered preferred for the on-ramp because the level of visibility of this structure is anticipated to be lower than the western overcrossing.
A conventional cast-in-place, reinforced concrete box girder alternative could also be feasible for the required span configuration. This structure type would increase its structure depth to a total of 7 feet. The substructure for this alternative would also be composed of seat type abutments founded on multiple rows of driven steel H-piles and a bent supported by single row of columns founded on Type II CIDH shafts. constructability and design compatibility with accommodating the horizontal curve on the structure. The primary disadvantage of this alternative is that the duration required to erect and remove falsework and for the superstructure to cure would correlate with an overall longer construction duration compared to other alternatives. However, the construction duration of this structure is not critical for this project.
Additionally, there is no minimum temporary vertical clearance requirement for this project because it does not cross over the freeway.
Even vertical clearance requirements are still met with the increased superstructure depth, this alternative is not considered to be the preferred alternative. The increase in concrete and reinforcement material costs is much greater in comparison to the cost of post-tensioning for Alternative 1. Additionally, the substructure elements would need to increase in size and/or length to support the increased dead loads as a result of an increased superstructure depth. Accordingly, this alternative would not be the most costeffective structure type.
The proposed structure type is a two-span cast-in-place, post-tensioned reinforced concrete box girder supported by seat type abutments founded on multiple rows of driven steel H-piles and a bent supported by single row of columns founded on Type II Cast-in-Drilled-Hole (CIDH) shafts. The structure depth will be 5 feet total with a total width of 39-feet 6-inches.
Alternatives analysis focused more on commonly economical structure types for the required span configuration. Other cast-in-place alternatives structure types were not considered accordingly. Precast alternatives were not considered because this structure type is typically less cost-effective than cast-inplace alternatives, especially for a structure with a horizontal curve, substantial vertical curve, and superelevation transition. Additionally, as discussed in the alternatives analysis section for the on-ramp structure, precast is not feasible for both structures. A steel superstructure was also not considered due to typically higher construction costs and increased maintenance needs compared to a concrete superstructure.
4.2.1 Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder (Preferred)
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 4-23 Page 292 of 1065 DRAFT
4.3 Foundations
4.3.1 Bents
4.3.2 Abutments
4.4 Constructability
4.4.1 Falsework
The following constructability considerations were also provided in the Draft SPGR for driven piles:
The erection and removal of falsework will be required for the construction of the preferred structure. The installation of falsework is not a constructability concern because the off-ramp structure does not cross over an open portion of road or freeway.
4.4.2 Deep Foundations
The Draft SPGR indicates that wet methods (slurry displacement) will likely be needed to construct the CIDH piles because of the groundwater elevation encountered in the previous borings at the project site.
Temporary casings could also be necessary to support the shaft during drilling and advancing the hole through soft ground, caving soil layers, and groundwater.
Driven steel H-piles are utilized instead of CIDH piles at the abutments. The driven piles are more costeffective than CIDH piles for the abutments because they do not need to be embedded deep into the relatively weak top of bedrock layer. Driven piles are more feasible at the abutment supports because the excavation required for constructing the pile cap is not considered an issue at the abutments, unlike the bent locations that are near US 101. Three rows of HP14x89 piles are anticipated at Abutment 3 to sufficiently resist the lateral load demands of a relatively tall abutment, while only two rows of HP14x89 piles are anticipated to be required at Abutment 1 due to the reduction in abutment height that the MSE "island" provides. Analysis of the lateral stability of the proposed pile layout will be performed after borings are completed for this project.
Type II CIDH shafts are utilized for the bent supports because they are identified as the preferred pile type in the Draft SPGR due to their constructability, cost-effectiveness, and lateral capacity. 6-foot diameter Type II CIDH shafts were selected to support the 4-foot diameter columns required by Caltrans SDC requirements. The Draft SPGR recommends that the CIDH piles be embedded into the Franciscan melange bedrock layer to achieve vertical capacity, which could be as low as 60-feet below the existing ground surface. The Draft SPGR also provides a figure that displays the required embedment into bedrock corresponding to the preliminary factored nominal resistance for various sizes of CIDH piles, which indicates that the vertical tip of a 6-foot diameter Type II pile would be roughly 110 feet below the existing ground surface.
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 4-24
Hard driving conditions could be associated with the denser layers of older alluvium or within the Franciscan melange bedrock. The bedrock may also have variable depths and variable driving conditions based on the presence of harder, more resistant blocks within the formation. Predrilling for pile installation could be necessary to penetrate into the bedrock to achieve the needed axial and lateral resistances.
Pile driving could be delayed if splicing of steel piles is needed if field conditions vary from observed conditions.
DRAFT
4.5 Barriers
4.6 Aesthetics
4.7 Cost Estimate
Alternative 1 - Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder Total Structure Construction Cost = $8,151,000o
Alternative 2 - Cast-in-Place, Conventional Reinforced Concrete Box Girder Total Structure Construction Cost = $9,357,000o
4.8 Recommendation
Aesthetics are anticipated to be proposed for the off-ramp structure, but options are still being evaluated.
Typical treatments that could be implemented include:
The piles for the abutment support at the MSE wall "island" fully provide vertical support for the bridge, while the MSE wall will help provide lateral resistance to the piles. The sequencing and methodology of constructing each of the MSE wall and the deep foundations for the abutment must be considered accordingly. Simple cutting and bending of the reinforcements for the MSE wall for installation of the piles is not recommended to be allowed. It is anticipated that a casing can be provided around each pile to ensure that an adequate area within the reinforced region for the wall is provided for each pile. The casing would then be filled with sand prior to constructing the pile cap so that the lateral resistance of the piles are not isolated from the MSE wall. Methodology for designing and installing the MSE wall reinforcement around these vertical obstructions is discussed in Section 5.4.2 of the FHWA GEC Oil and the Type Selection Report for the retaining walls.
Both edges of deck will support Caltrans Standard Plan Type 836 concrete barriers. The barriers will support tubular handrailing that will be in accordance with the Caltrans Standard Plans.
Alternative 1 - Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder is the preferred alternative because it provides the most cost-effective solution for this site.
A standard one-way flare at the top of the columns at the bent. The flare would be architectural only, with a horizontal gap provided between the top of the column and the superstructure beyond the structural section.
Black paint coating incorporated for the tubular handrailing installed on top of the Type 836 barriers, for both the desired appearance and to help protect the railing from corrosion.
General Plan Estimates for both alternatives were prepared utilizing unit costs determined from available Caltrans Contract Cost Data and from bid results for previous projects. A 10% mobilization, a 25% contingency, and a 6.19% escalation rate were added to the subtotal of construction costs. The estimated cost for both alternatives is shown below:
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 4-25
4.4.3 MSE Wall “Island”
DRAFT
CHAPTER 5 US 101 NORTHBOUND ON-RAMP STRUCTURE
5.1 Preferred Structure Type Summary
Table 5-1 | Structure Summary - US 101 NB On-Ramp
Bridge Name US 101 NB On-Ramp
Bents
Vertical Clearance
Approaches
Deck Protection
Drains
Profile
Abutments
Future Widening
Aesthetics
Temperature Range
Joints
Utilities
Loading
Bridge Number
Structure Type
Structure Cost
Spans
Structure Depth
Depth-to-Span Ratio
Structure Width
Temporary Vertical
Clearance
Barriers/Sidewalks
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 5-1
LEOD: Type 836 Concrete Barrier
REOD: Type 836 Concrete Barrier
Abutment 1: Structure Approach Type N (Mod)
Abutment 3: Structure Approach Type N (30)
This structure is in a Non-Freeze-Thaw Area, in which deck salting does not occur. No special deck protection is required.
Deck Drainage will be required. Drain location and layout are pending.
Interdisciplinary coordination will be required to determine viability of drainage pipe to storm drain connections at columns and abutments.
10° to 80°
Abutment 1 & 3: Type B Joint Seal (MR = 2")
None.
Live Load (LL): HL93 and permit design load
Dead Load (DC): Type 836 barriers and railing
Additional Dead Load (DW): 35 psf for future wearing surface None.
TBD
TBD
Cast-In-Place, Post-Tensioned Reinforced Concrete Box Girder $9,427,000
Span 1-2 = 125'-0"; Total Length = 250-0"
5'-0"
Spans 1-2: 0.040
31'-6" minimum total width at Abut 3 & varies to 67'-0" maximum total width at Abut 1, including:
■ l-12'-0" Minimum & Varies Lane (16' minimum on structure) ■ 4'-0" Minimum & Varies Shoulder at LEOD
■ 8'-0" Minimum & Varies Shoulder at REOD
Superelevated, with a superelevation transition across its length Abut 1: Seat Type Abutment on Three Rows of HP14x89 Piles Abut 3: Seat Type Abutment on Two Rows of HP14x89 Piles Bent 2: Integral bent cap with a single row of 2 - 4'-0" diameter columns pinned top founded on 6'-0" diameter Type II CIDH piles
2'-0" minimum freeboard over 50-year WSE and 0' minimum freeboard over 100- year WSE is met over full length
None.
DRAFT
5.2 Structure Type Alternatives
This structure type results in the lowest construction cost and provides visual consistency with the overcrossing. The ability to form the superstructure on-site provides the advantage of increased
5.2.2 Cast-in-Place, Conventional Reinforced Concrete Box Girder
5.2.3 Other Alternatives
A variable depth box girder bridge with a parabolic soffit could be considered for this site if desired. Even though providing a parabolic flare in the soffit typically reduces the total material required for the construction of the superstructure, it could potentially result in a minor increase in construction costs due to the increase in complexity of the formwork. This alternative is not considered preferred for the off-ramp because the level of visibility of this structure is anticipated to be lower than the western overcrossing.
A conventional cast-in-place, reinforced concrete box girder alternative could also be feasible for the required span configuration. This structure type would increase its structure depth to a total of 7 feet. The substructure for this alternative would also be composed of seat type abutments founded on multiple rows of driven steel H-piles and a bent supported by single row of columns founded on Type II CIDH shafts. constructability and design compatibility with accommodating the horizontal curve and varied width of the structure. The primary disadvantage of this alternative is that the duration required to erect and remove falsework and for the superstructure to cure would correlate with an overall longer construction duration compared to other alternatives. However, the construction duration of this structure is not critical for this project. Additionally, there is no minimum temporary vertical clearance requirement for this project because it does not cross over the freeway.
Alternatives analysis focused more on commonly economical structure types for the required span configuration. Other cast-in-place alternatives structure types were not considered accordingly. Precast alternatives were not considered because this structure type is typically less cost-effective than cast-inplace alternatives, especially for a structure with a horizontal curve, substantial vertical curve, and superelevation transition. Additionally, the significant difference in width between Abutment 1 and Bent 2, as much as a 27-foot differential, would not be feasible to accommodate with a precast alternative. A steel superstructure was also not considered due to typically higher construction costs and increased maintenance needs compared to a concrete superstructure.
Even vertical clearance requirements are still met with the increased superstructure depth, this alternative is not considered to be the preferred alternative. The increase in concrete and reinforcement material costs is much greater in comparison to the cost of post-tensioning for Alternative 1. Additionally, the substructure elements would need to increase in size and/or length to support the increased dead loads as a result of an increased superstructure depth. Accordingly, this alternative would not be the most costeffective structure type.
The proposed structure type is a two-span cast-in-place, post-tensioned reinforced concrete box girder supported by seat type abutments founded on multiple rows of driven steel H-piles and a bent supported by single row of columns founded on Type II Cast-in-Drilled-Hole (CIDH) shafts. The structure depth will be 5 feet total with a varying total width between 31-feet 6-inches and 67-feet.
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 5-2
5.2.1 Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder (Preferred)
DRAFT
5.3 Foundations
5.3.1 Bents
5.3.2 Abutments
5.4 Constructability
5.4.1 Falsework
The following constructability considerations were also provided in the Draft SPGR for driven piles:
The erection and removal of falsework will be required for the construction of the preferred structure. The installation of falsework is not a constructability concern because the ol-ramp structure does not cross over an open portion of road or freeway.
5.4.2 Deep Foundations
The Draft SPGR indicates that wet methods (slurry displacement) will likely be needed to construct the CIDH piles because of the groundwater elevation encountered in the previous borings at the project site.
Temporary casings could also be necessary to support the shaft during drilling and advancing the hole through soft ground, caving soil layers, and groundwater.
Driven steel H-piles are utilized instead of CIDH piles at the abutments. The driven piles are more costeffective than CIDH piles for the abutments because they do not need to be embedded deep into the relatively weak top of bedrock layer. Driven piles are more feasible at the abutment supports because the excavation required for constructing the pile cap is not considered an issue at the abutments, unlike the bent locations that are near US 101. Three rows of HP14x89 piles are anticipated at Abutment 1 to sufficiently resist the lateral load demands of a relatively tall abutment, while only two rows of HP14x89 piles are anticipated to be required at Abutment 3 due to the reduction in abutment height that the MSE "island" provides. Analysis of the lateral stability of the proposed pile layout will be performed after borings are completed for this project.
Type II CIDH shafts are utilized for the bent supports because they are identified as the preferred pile type in the Draft SPGR due to their constructability, cost-effectiveness, and lateral capacity. 6-foot diameter Type II CIDH shafts were selected to support the 4-foot diameter columns required by Caltrans SDC requirements. The Draft SPGR recommends that the CIDH piles be embedded into the Franciscan melange bedrock layer to achieve vertical capacity, which could be as low as 60-feet below the existing ground surface. The Draft SPGR also provides a figure that displays the required embedment into bedrock corresponding to the preliminary factored nominal resistance for various sizes of CIDH piles, which indicates that the vertical tip of a 6-foot diameter Type II pile would be roughly 110 feet below the existing ground surface.
Hard driving conditions could be associated with the denser layers of older alluvium or within the Franciscan melange bedrock. The bedrock may also have variable depths and variable driving conditions based on the presence of harder, more resistant blocks within the formation. Predrilling for pile installation could be necessary to penetrate into the bedrock to achieve the needed axial and lateral resistances.
Pile driving could be delayed if splicing of steel piles is needed if field conditions vary from observed conditions.
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 5-3 Page 298 of 1065 DRAFT
5.5 Barriers
5.6 Aesthetics
5.7 Cost Estimate
Alternative 1 - Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder Total Structure Construction Cost = $9,427,000o
Alternative 2 - Cast-in-Place, Conventional Reinforced Concrete Box Girder Total Structure Construction Cost = $10,832,000o
5.8 Recommendation
Aesthetics are anticipated to be proposed for the off-ramp structure, but options are still being evaluated.
Typical treatments that could be implemented include:
The piles for the abutment support at the MSE wall "island" fully provide vertical support for the bridge, while the MSE wall will help provide lateral resistance to the piles. The sequencing and methodology of constructing each of the MSE wall and the deep foundations for the abutment must be considered accordingly. Simple cutting and bending of the reinforcements for the MSE wall for installation of the piles is not recommended to be allowed. It is anticipated that a casing can be provided around each pile to ensure that an adequate area within the reinforced region for the wall is provided for each pile. The casing would then be filled with sand prior to constructing the pile cap so that the lateral resistance of the piles are not isolated from the MSE wall. Methodology for designing and installing the MSE wall reinforcement around these vertical obstructions is discussed in Section 5.4.2 of the FHWA GEC Oil and the Type Selection Report for the retaining walls.
Both edges of deck will support Caltrans Standard Plan Type 836 concrete barriers. The barriers will support tubular handrailing that will be in accordance with the Caltrans Standard Plans.
Alternative 1 - Cast-in-Place, Post-Tensioned Reinforced Concrete Box Girder is the preferred alternative because it provides the most cost-effective solution for this site.
A standard one-way flare at the top of the columns at the bent. The flare would be architectural only, with a horizontal gap provided between the top of the column and the superstructure beyond the structural section.
Black paint coating incorporated for the tubular handrailing installed on top of the Type 836 barriers, for both the desired appearance and to help protect the railing from corrosion.
General Plan Estimates for both alternatives were prepared utilizing unit costs determined from available Caltrans Contract Cost Data and from bid results for previous projects. A 10% mobilization, a 25% contingency, and a 6.19% escalation rate were added to the subtotal of construction costs. The estimated cost for both alternatives is shown below:
D218721CA.00 • July 2026 • Prado Road Interchange • City of San Luis Obispo Bridge Type Selection Report • Page 5-4
5.4.3 MSE Wall “Island”
APPENDIX A: 35% Bridge Plans
7consor
Dist COUNTY ROUTE
5 SLO US 101 1
50+32.48 EVC
30% SUBMITTAL
ROFESS/o,, REGISTERED CIVIL ENGINEER DATE
/
/ /
280’ VC 250’ VC s /SCOTT MCCAULEY \
0.87%
240’ VC 4.90% -4.90% 275’ VC 0.64% PLANS APPROVAL DATE
R/C = -2.1046% / Sta R/C = -1.5618% / Sta Exp. R/C = 1.6787% / Sta R/C = 2.0124% / Sta
OF CALN
PROFILE GRADE
No Scale Aconsor P: 916.368.9181
Notes
450‘-O" Measured along "P" Line EB BB
150-0” 150-0” 150’-0”
9 *Oqt
"P" Line
J 65’-4”
I
Abut 4 28’—8” 36-8”
Abut 1 Bent 2 3g0
Approx OG r-o” 6‘-2"4-0‘ 12’-0” 11’-0” 12’-0” 4-0" 14’-2” j
00 Datum Elev = 80.0
46+00 47+00 48+00 49+00 50+00 51+00 PG
/
1.5% 2.0% 2.0% 1.5%
OR 60" Dia Column, Typ
Approx OG t Pe
r
1 F — L -L F—L
t
CURVE DATA 7 (
k:
"N" Lines’ 5’
TYPICAL SECTION
1 - -
10’ . 24’ . . 24’ . 10’ 1" = 10’
1s ©
.00 , | \
=T
Lu
-R=675.00’
EB 50+75. TRAFFIC NOTES
46 8-Eley 160.87* r.
VEHICULAR TRAFFIC:
■co
L
3 47
4 48 49 5150+00 Stage construction will will not be required.
Typ (6 1
■
Typ (3
CM
76+91.83 EC
(O
"F" LINEi
N
O
CHECKED HL93 W/HLOW—BOY' T. Eaton PRADO ROAD INTERCHANGE CHECKED *y T. Eaton
DESIGN OVERSIGHT DETAILS
QUANTITIES
CHECKED
SPECIFICATIONS GENERAL PLAN NO. 1 - ALT 1
T T
I
| REWSION OATES
7/2/26 I I
T T
FILE A:\_V-TPD\Projects\CA\Son Luis 0bispo\D218721CA.00_Prodo\500-Design\505 - CADD Files\Bridge\D218721a-o-gpO1.dwg I
_____ No falsework allowed over traffic.
__X_ Falsework opening(s) required:_____ Temporary traffic lane reduction needed for footing excavation.
Concrete Barrier
Type 732SW, Typ
Legend
(1) Paint "Prado Rd Overcrossing”(2) Paint "Br No. XXX-XXXX”(3) MSE Wall, see "Retaining Wall" sheets (4) Structure Approach Type N (30)
(5) Structure Approach Type N (Mod)(6) Joint Armor(7) Exist Double Thrie Beam Barrier © Point of Minimum vertical Clearance
DISREGARD PRINTS BEARINGEARLIER REVISION DATES
POST MILES
TOTAL PROJECT
26.8/27.3
TOTAL
SHEETS
EUANSAANP SPECS
00 S
ORIGINAL SCALE IN INCHES
FOR REDUCED PLANS
SHEET
No.
O
CM
NB US 101SB US 101
Scott McCauley
PROJECT ENGINEER
A.B.
C71495
. 12/31/27)CIVIL 7
PLAN
1” = 40’
For General Notes, see "Deck Contours" sheet.
For Hydrologic Summary, see ’’Foundation Plan" sheet.For Utilities, see "Typical Section" sheet.
Temp Vertical
Clearance
15’—0”
15’-0”
OF
4. _X__ Traffic will pass under the structure on
NB US 101, SB US 101
CONSOR NORTH AMERICA, INC.2868 PROSPECT PARK DR, STE 250 RANCHO CORDOVA, CA 95670
Note:
The Contractor must verify all
controlling field dimensions before
ordering or fabricating any material.
LOAD & RESISTANCE
FACTOR DESIGN
58+47.81 EVCElev 135.95
UNIT: UNITPROJECT NUMBER & PHASE: PROJECT COMBERT NO.: CONTRACT
1. 2.3.
43+97.70 BVCElev 143.27
BB 46+25.00Elev 149.59
1.2.3. Tubular
Handrailing, Typ
46+37.70 EVCElev 150.20
161.29
50+86.37 BVC Elev 160.75
84” Dia CIDH
Pile, Typ
53+36.37 EVC
Elev 153.39
THE STATE OF CALIFORNIA OR ITS OFFICERS
OR AGENTS SHALL NOT BE RESPONSIBLE FOR
THE ACCURACY OR COMPLETENESS OF SCANNED
COPIES OF THIS PLAN SHEET.
Bent 3
47+52.48 BVCElev 155.82
SIGN OFF DATEDESIGN DETAIL SHEET (ENGUISH) (REV.7/16/10) | ”P” Line
S 62’55’10” E
55+72.81 BVCElev 141.81
R=675.00’A =35’ 07’ 53”T=213.68’L=413.88’
00 8
BRIDGE NO.
XX-XXXX
POST MILE
26.8 PREPARED FOR THE
CITY OF SAN LUIS OBISPO
PUBLIC WORKS DEPARTMENT
6 D. Polglase
3 PERMIT DESIGN VEHICLE
To S. Higuera
Street
LIVE LOADING:
-
2 Width of
Traffic Opening
39’—0” 39-0”
____ New alignment. No traffic at the site.____ Traffic will be detoured away from the site.____ Traffic will be carried on the structure. s
1-0”
DEVELOPED ELEVATION
1” = 40’
%
Dist COUNTY ROUTE
50+32.48 EVC 5 SLO US 101 2
30% SUBMITTAL
ROFESS/o,,
/
REGISTERED CIVIL ENGINEER DATE
/ /
250’ VC
0.87%
240’ VC 4.90% -4.90% 275’ VC 0.64%
R/C = -2.1046% / Sto
No. R/C 1.5618% / Sta PLANS APPROVAL DATE
R/C = 1.6787% / Sta R/C = 2.0124% / Sta Exp.
3 OF CALN og"
PROFILE GRADE
Aconsor
No Scale
P: 916.368.9181
Notes
450‘-O" Measured along "P" Line EB BB
150-0” 150-0” 150’-0”
&
"P" Line
5 I
3 65-4”
+
Abut 4 28-8” 36’-8” Bent 3 Abut 1 Bent 2
Approx OG 1-0” 6‘—2"4-0‘ 12’-0" n’-o” 12-0” 4-0 14-2” 1’-0” Datum Elev = 80.0
46+00 47+00 48+00 49+00 50+00 51+00
PG
]
60" Dia Column, Typ
Approx OG
t
CURVE DATA
l N
J
------
7 "N" Line --h 84" Dia CIDH pile, Typ
5’ 5’
k: ki k:
1 - - AOne
10’ . 24’ . . 24’ . 10’
Ch TYPICAL SECTION 1s
1” = 10’
Lu
-R=675.00’
Elev 160.87 TRAFFIC NOTES
,46
r.
VEHICULAR TRAFFIC:
■co
L
3 47
4 48 49 51
I Stage construction will will not be required.
_X__ Traffic will pass under the structure on
Typ (6 1 NB US 101, SB US 101
1 Typ (3
76+91.83 EC
O
5 co
"F" LINE-
■
CM
O
CHECKED HL93 W/HLOW—BOY' T. Eaton DES CHK PRADO ROAD INTERCHANGE
PERMIT DESIGN VEHICLE
6 D. Polglase
CHECKED
*y T. Eaton
DESIGN OVERSIGHT DETAILS DET CHK LAYOUT CHECK
QUANTITIES BY QTY BY
CHECKEDQTY CHK SPECIFICATIONS BY SPECS BY SPEC CHECK GENERAL PLAN NO. 1 - ALT 2 T T
I
I REW । -. DATES | ShEET T
7/2/26 I l P I
T
FILE A:\_V-TPD\Projects\CA\Son Luis 0bispo\D218721CA.00_Prodo\500-Design\505 - CADD Files\Bridge\D218721a-o-gpO2.dwg I
Concrete Barrier
Type 732SW, Typ
Concrete
Bent Cap
Legend
(1) Paint "Prado Rd Overcrossing”(2) Paint ”Br No. XXX-XXXX”(3) MSE Wall, see "Retaining Wall" sheets (4) Structure Approach Type N (30)
(5) Structure Approach Type N (Mod)(6) Joint Armor(7) Exist Double Thrie Beam Barrier © Point of Minimum vertical Clearance
DISREGARD PRINTS BEARING EARLIER REVISION DATES
POST MILES
TOTAL PROJECT
26.8/27.3
TOTAL
SHEETS
EUANSAANP SPECS
00 S
3 2
ORIGINAL SCALE IN INCHES
FOR REDUCED PLANS
SHEET
No.
O
CM
P/S CA Wide Flange
Conc Girder, Typ
Scott McCauley
PROJECT ENGINEER
C71495
. 12/31/27, CIVIL 7
For General Notes, see "Deck Contours" sheet.
For Hydrologic Summary, see ’’Foundation Plan" sheet.For Utilities, see "Typical Section" sheet. _____No falsework allowed over traffic.
_____Falsework opening(s) required:
_____ Temporary traffic lane reduction needed for
footing excavation.
PLAN
1” = 40’
UNIT: UNITPROJECT NUMBER & PHASE: PROJECT COMBERT NO.: CONTRACT TubularHandrailing, Typ
58+47.81 EVCElev 135.95
CONSOR NORTH AMERICA, INC.2868 PROSPECT PARK DR, STE 250 RANCHO CORDOVA, CA 95670
Note:
The Contractor must verify all
controlling field dimensions before
ordering or fabricating any material.
LOAD & RESISTANCE
FACTOR DESIGN
1. 2.3.
BB 46+25.00Elev 149.59
161.2950+86.37 BVCElev 160.75
1. 2.3.
53+36.37 EVC
Elev 153.39
46+37.70 EVCElev 150.20
| "P” Line
S 62’55’10” E
THE STATE OF CALIFORNIA OR ITS OFFICERS
OR AGENTS SHALL NOT BE RESPONSIBLE FOR
THE ACCURACY OR COMPLETENESS OF SCANNED
COPIES OF THIS PLAN SHEET.
A.B.C.
So
co
55+72.81 BVC
Elev 141.81
43+97.70 BVCElev 143.27
SIGN OFF DATEDESIGN DETAIL SHEET (ENGUISH) (REV.7/16/10) R=675.00’A =35’ 07’ 53”T=213.68’L=413.88’
00 8
47+52.48 BVCElev 155.82
280’ VC
BRIDGE NO.
XX-XXXX
POST MILE
26.8 PREPARED FOR THE
CITY OF SAN LUIS OBISPO
PUBLIC WORKS DEPARTMENT
LIVE LOADING:
DEVELOPED ELEVATION
1” = 40’
____ New alignment. No traffic at the site.____ Traffic will be detoured away from the site.____ Traffic will be carried on the structure. 3/SCOTT MCCAULE1
8-
5 50+00
- — To S. Higuera
Street
o
EB 50+75.00
Ele'
.J \ G
1
Dist COUNTY ROUTE
5 SLO US 101 3
50+32.48 EVC
30% SUBMITTAL
ROFESS/o,, REGISTERED CIVIL ENGINEER DATE
/
/ /
250’ VC s /SCOTT MCCAULEY \
0.87%
240’ VC 4.90% -4.90% 275’ VC 0.64% PLANS APPROVAL DATE
R/C = -2.1046% / Sta R/C = -1.5618% / Sta Exp. R/C = 1.6787% / Sta R/C = 2.0124% / Sta
OF CALN
Aconsor P: 916.368.9181
BB 300‘-0" Measured along "P" Line EB
150’—0" 150’—0”
3 "P" Line
FG I
87‘-4" Max & Var
Bent 2
Approx OG 1’-O” n’-o” 6’-2”4’-(J 12-0” 11’-0"
39‘-8" Max & Var 47‘-8" Max & Var +11-0” T-O” 11’-0” 5—0‘ 14’-2” Datum Elev = 80.0 &Var
52+00 53+00 54+00 55+00
71.5%, 2.0% 2.0%. 1
DEVELOPED ELEVATION
1” = 40’
60" Dia Column, Typ »
o
Approx OG Pe
(o
I--h -h I-h 84" Dia CIDH Pile, Typ
t
ki J k: k: k:
TYPICAL SECTION
1” = 10’
1&()
5 /
I
52 53 55 56 —E
@
To S. Higuera
Street
6)
Typ
3)
Typ
CHECKED HL93 W/HLOW—BOY' T. Eaton DES CHK PERMIT DESIGN VEHICLE PRADO ROAD INTERCHANGE 6 D. Polglase
CHECKED
*y T. Eaton
DESIGN OVERSIGHT DETAILS DET CHK LAYOUT CHECK
QUANTITIES BY QTY BY
CHECKEDQTY CHK SPECIFICATIONS BY SPECS BY SPEC CHECK GENERAL PLAN NO. 2 - ALT 1 T T
I
I REW । -. DATES | ShEET T
6/5/26 I I h |
T
FILE A:\_V-TPD\Projects\CA\Son Luis 0bispo\D218721CA.00_Prodo\500-Design\505 - CADD Files\Bridge\D218721b-o-gpO1.dwg I
Concrete Barrier
Type 732SW, Typ
Legend
(1) Paint "Prado Rd Overcrossing”(2) Paint ”Br No. XXX-XXXX”(3) MSE Wall, see "Retaining Wall" sheets (4) Structure Approach Type N (30)
(5) Structure Approach Type N (Mod)(6) Joint Armor
To Froom
Ranch Way
DISREGARD PRINTS BEARING EARLIER REVISION DATES
2.3. TubularHandrailing, Typ
POST MILES
TOTAL PROJECT
26.8/27.3
TOTAL
SHEETS
EUANSAANP SPECS
ORIGINAL SCALE IN INCHES
FOR REDUCED PLANS
Scott McCauley
PROJECT ENGINEER
Note:
The Contractor must verify all
controlling field dimensions before
ordering or fabricating any material.
SHEET
No.
C71495
. 12/31/27)CIVIL 7
BB 52+00.00Elev 158.62
CONSOR NORTH AMERICA, INC.2868 PROSPECT PARK DR, STE 250 RANCHO CORDOVA, CA 95670
LOAD & RESISTANCE
FACTOR DESIGN
EB 55+00.00Elev 145.37
UNIT: UNITPROJECT NUMBER & PHASE: PROJECT COMBERT NO.: CONTRACT PLAN
1” = 40’
46+37.70 EVCElev 150.20
53+36.37 EVCElev 153.39
43+97.70 BVCElev 143.27
SIGN OFF DATEDESIGN DETAIL SHEET (ENGUISH) (REV.7/16/10) 161.29
50+86.37 BVC
Elev 160.75
THE STATE OF CALIFORNIA OR ITS OFFICERS
OR AGENTS SHALL NOT BE RESPONSIBLE FOR
THE ACCURACY OR COMPLETENESS OF SCANNED
COPIES OF THIS PLAN SHEET.
47+52.48 BVCElev 155.82
280’ VC
58+47.81 EVC
Elev 135.95
"P" Line
S 62-45’46” E
PREPARED FOR THE
CITY OF SAN LUIS OBISPO
PUBLIC WORKS DEPARTMENT
BRIDGE NO.
XX-XXXX
POST MILE
26.8 55+72.81 BVCElev 141.81
Abut 3
3 LIVE LOADING:
-
2 Notes1. For General Notes, see "Deck Contours" sheet.
Abut 1
Var"
PP
-
54 PROFILE GRADE
No Scale
For Hydrologic Summary, see "Foundation Plan" sheet.
For Utilities, see "Typical Section" sheet.
Dist COUNTY ROUTE
5 SLO US 101 4
50+32.48 EVC
30% SUBMITTAL
ROFESS/o,, REGISTERED CIVIL ENGINEER DATE
/
/ /
250’ VC s /SCOTT MCCAULEY \
0.87%
240’ VC 4.90% -4.90% 275’ VC 0.64% PLANS APPROVAL DATE
R/C = -2.1046% / Sta R/C = -1.5618% / Sta Exp. R/C = 1.6787% / Sta R/C = 2.0124% / Sta
OF CALN
Aconsor
P: 916.368.9181
BB 300‘-0" Measured along "P" Line EB
150’—0" 150’-0”
"P" Line
3 G 87‘-4" Max & Var
7 I
39‘-8" Max & Var 47‘-8" Max & Var
1 ’-0” 6‘-2"4-0‘ 12’-0” 11’-0” n’-o” 11’-o” 5-0" 14’-2” 1’-O” Approx OG
Datum Elev = 80.0
1.5% 2.0% 2.0%. .1.5% 52+00 53+00 54+00 55+00
DEVELOPED ELEVATION
1” = 40’
]
60" Dia Column, Typ
Approx OG
t
-h I--h I--h 84" Dia CIDH pile, Typ
1= k k
TYPICAL SECTION
1&() 1” = 10’
5 /
52 53 55 56 —E
@
To S. Higuera
Street
6)
Typ
3)
Typ
CHECKED HL93 W/HLOW—BOY' T. Eaton DES CHK PERMIT DESIGN VEHICLE PRADO ROAD INTERCHANGE 6 D. Polglase
CHECKED
*y T. Eaton
DESIGN OVERSIGHT DETAILS DET CHK LAYOUT CHECK
QUANTITIES BY QTY BY
CHECKEDQTY CHK SPECIFICATIONS BY SPECS BY SPEC CHECK GENERAL PLAN NO. 2 - ALT 2 T T
I
| REWSION DATES
6/5/26 I I
-
T
FILE A:\_V-TPD\Projects\CA\Son Luis 0bispo\D218721CA.00_Prodo\500-Design\505 - CADD Files\Bridge\D218721b-o-gpO2.dwg I
Concrete Barrier
Type 732SW, Typ
To Froom
Ranch Way
Concrete
Bent Cap
Legend
(1) Paint "Prado Rd Overcrossing”(2) Paint ”Br No. XXX-XXXX”(3) MSE Wall, see "Retaining Wall" sheets (4) Structure Approach Type N (30)
(5) Structure Approach Type N (Mod)(6) Joint Armor
DISREGARD PRINTS BEARING EARLIER REVISION DATES
2.3. 11’-0”
& Var
TOTAL
SHEETS
Tubular
Handrailing, Typ
POST MILES
TOTAL PROJECT
26.8/27.3
EUANSAANP SPECS
ORIGINAL SCALE IN INCHES
FOR REDUCED PLANS
Scott McCauley
PROJECT ENGINEER
Note:
The Contractor must verify all
controlling field dimensions before
ordering or fabricating any material.
SHEET
No.
C71495
. 12/31/27)CIVIL 7
BB 52+00.00Elev 158.62
P/S CA Wide Flange
Conc Girder, Typ
CONSOR NORTH AMERICA, INC.2868 PROSPECT PARK DR, STE 250 RANCHO CORDOVA, CA 95670
LOAD & RESISTANCE
FACTOR DESIGN
PLAN
1” = 40’
EB 55+00.00Elev 145.37
UNIT: UNITPROJECT NUMBER & PHASE: PROJECT COMBERT NO.: CONTRACT 46+37.70 EVCElev 150.20
53+36.37 EVCElev 153.39
43+97.70 BVCElev 143.27
SIGN OFF DATEDESIGN DETAIL SHEET (ENGUISH) (REV.7/16/10) 161.29
50+86.37 BVC
Elev 160.75
THE STATE OF CALIFORNIA OR ITS OFFICERS
OR AGENTS SHALL NOT BE RESPONSIBLE FOR
THE ACCURACY OR COMPLETENESS OF SCANNED
COPIES OF THIS PLAN SHEET.
47+52.48 BVCElev 155.82
280’ VC
58+47.81 EVC
Elev 135.95
PREPARED FOR THE
CITY OF SAN LUIS OBISPO
PUBLIC WORKS DEPARTMENT
BRIDGE NO.
XX-XXXX
POST MILE
26.8 55+72.81 BVCElev 141.81
"P" Line
S 62-45’46” E
Abut 3
3 LIVE LOADING:
-
2 Notes1. For General Notes, see "Deck Contours" sheet.
Abut 1
-
54 PROFILE GRADE
No Scale
For Hydrologic Summary, see ’’Foundation Plan" sheet.
For Utilities, see "Typical Section" sheet.
*
l+
-
Bent 2
Dist COUNTY ROUTE
5 SLO US 101 5
30% SUBMITTAL
/
RVROFESS/o,, REGISTERED CIVIL ENGINEER DATE
)_______
2.00%
'SCOTT MCCAULEY 3.73%
500’ VC R/C = -0.8663% / Sta PLANS APPROVAL DATE
Exp.
R/C 0.8465% / Sta
OF CALN
Aconsor P: 916.368.9181
250‘-0" Measured along "F" Line BB EB
"F" Line 125-0” 125’—0”
39-6”
3 T-9” 4’—0” 12-0” 12’-0” 8’-0”
I
5 3
PG
SR
=T Approx OG Abut 3
Abut 1 Bent 2
Datum Elev = 100.0
75+00 76+00 77+00
DEVELOPED ELEVATION
1” = 20’
Approx OG
A
o
3 m
0) TYPICAL SECTION
O) 1/4” = 1-0”
IO
N 32*45′32” E ID
75+00 r ‘F”LINE
r
N 27’04’50" E
76 77 T
"F" 77+86.24 ="P” 51+1 5.24
I
3 Lu
(
Typ (3
CHECKED HL93 W/HLOW—BOY' A. Hanson
CHECKED PRADO ROAD INTERCHANGE
2 A. Hanson
DESIGN OVERSIGHT DETAILS
QUANTITIES
CHECKED
SPECIFICATIONS GENERAL PLAN NO. 3 - ALT 1 S
T T
I
I REW I ■ DATES I SHEET I
6/4/26 I I I 5 I
T T
FILE A:\_V-TPD\Projects\CA\Son Luis 0bispo\D218721CA.00_Prodo\500-Design\505 - CADD Files\Bridge\D218721c-o-gp01.dwg I
48" Dia Conc
Column, Typ-
(1) Paint ’’US 101 NB Off-Ramp”(2) Paint ”No. XXX-XXXX”(3) MSE Wall, see "Retaining Wall" sheets (4) Structure Approach Type N (30)
(5) Structure Approach Type N (Mod)
DISREGARD PRINTS BEARING EARLIER REVISION DATES
Conc BarrierType 836, Typ
2.3. CIP/PT Conc
Box Girder —
POST MILES
TOTAL PROJECT
26.8/27.3
TOTAL
SHEETS
EUANSAANP SPECS
To Prado
Road
ORIGINAL SCALE IN INCHES
FOR REDUCED PLANS
Scott McCauley
PROJECT ENGINEER
SHEET
No.
O CO
0 I
I
I
C71495
. 12/31/27)CIVIL 7
1 •0&
N)CO
Note:
The Contractor must verify all
controlling field dimensions before
ordering or fabricating any material.
EB 77+26.68Elev 159.21
71+62.76 EVCElev 139.99
CONSOR NORTH AMERICA, INC.2868 PROSPECT PARK DR, STE 250 RANCHO CORDOVA, CA 95670
LOAD & RESISTANCE
FACTOR DESIGN
BB 74+76.68Elev 151.71
UNIT: UNITPROJECT NUMBER & PHASE: PROJECT COMBERT NO.: CONTRACT 77+21.06 EVCElev 159.09
72” Dia CIDH pile, Typ
SIGN OFF DATEDESIGN DETAIL SHEET (ENGUISH) (REV.7/16/10) PLAN
1” = 20’
THE STATE OF CALIFORNIA OR ITS OFFICERS
OR AGENTS SHALL NOT BE RESPONSIBLE FOR
THE ACCURACY OR COMPLETENESS OF SCANNED
COPIES OF THIS PLAN SHEET.
PREPARED FOR THE
CITY OF SAN LUIS OBISPO
PUBLIC WORKS DEPARTMENT
CM----------
ID
BRIDGE NO.
XX-XXXX
POST MILE
26.8 6 D. Polglase
u 8
PERMIT DESIGN VEHICLE
LIVE LOADING:
75+21.06 BVCElev 153.36
200’ VC
Notes
1. For General Notes, see "Deck Contours" sheet.
1’-9”
CURVE DATA
R=1000.00’A=5* 40’ 43”T=49.59’L=99.11’
PROFILE GRADE
No Scale
For Hydrologic Summary, see "Foundation Plan" sheet. For Utilities, see "Typical Section" sheet.
Dist COUNTY ROUTE
5 SLO US 101 6
30% SUBMITTAL
/
RVROFESS/o,, REGISTERED CIVIL ENGINEER DATE
)__________
2.00%
'SCOTT MCCAULEY 3.73%
500’ VC R/C = -0.8663% / Sta PLANS APPROVAL DATE
Exp.
R/C 0.8465% / Sta
OF CALN
Aconsor P: 916.368.9181
250‘-0" Measured along "F" Line BB EB
"F" Line 125-0” 125’—0”
39-6”
r-9” 4’—0” 12-0” 12’-0” 8’-0”
f
I
3 1 PG
SR
===a Approx OG T
Abut 3
Abut 1 Bent 2
O
CIP/RC Box Girder
Datum Elev = 100.0
75+00 76+00 77+00
DEVELOPED ELEVATION
1” = 20’
Approx OG
A
o
3 m
0) TYPICAL SECTION
in
O) 1/4” = 1-0”
5 N3245‘32"E m
75+00 r "F”LINE N 27*04’50" E
76 1&(2) 77
"F" 77+86.24 ="P" 51+1 5.24
I
3 Luin
Typ (3
CHECKED HL93 W/HLOW—BOY' A. HansonCHECKED PRADO ROAD INTERCHANGE 2 A. Hanson
DESIGN OVERSIGHT DETAILS
QUANTITIES
CHECKED
SPECIFICATIONS GENERAL PLAN NO. 3 - ALT 2
T T
I
I REW । -. DATES | ShEET T
6/3/26 I I I 6 I
T T
FILE A:\_V-TPD\Projects\CA\Son Luis 0bispo\D218721CA.00_Prado\500-Design\505 - CADD Files\Bridge\D218721c-o-gp02.dwg I
48" Dia Conc
Column, Typ-
(1) Paint ’’US 101 NB Off-Ramp”(2) Paint ”No. XXX-XXXX”(3) MSE Wall, see "Retaining Wall" sheets (4) Structure Approach Type N (30)
(5) Structure Approach Type N (Mod)
DISREGARD PRINTS BEARINGEARLIER REVISION DATES
Conc BarrierType 836, Typ
2.3. POST MILES
TOTAL PROJECT
26.8/27.3
TOTAL
SHEETS
EUANSAANP SPECS
To Prado
Road
ORIGINAL SCALE IN INCHES
FOR REDUCED PLANS
Scott McCauley
PROJECT ENGINEER
OCO
0 SHEET
No.
I
I
I
C71495
. 12/31/27)CIVIL 7
1 •0&
N)CO
Note:
The Contractor must verify all
controlling field dimensions before
ordering or fabricating any material.
EB 77+26.74Elev 159.21
71+62.76 EVCElev 139.99
CONSOR NORTH AMERICA, INC.2868 PROSPECT PARK DR, STE 250 RANCHO CORDOVA, CA 95670
LOAD & RESISTANCE
FACTOR DESIGN
BB 74+76.68Elev 151.71
UNIT: UNITPROJECT NUMBER & PHASE: PROJECT COMBERT NO.: CONTRACT 72” Dia CIDH pile, Typ
77+21.06 EVCElev 159.09
SIGN OFF DATEDESIGN DETAIL SHEET (ENGUISH) (REV.7/16/10) PLAN
1” = 20’
THE STATE OF CALIFORNIA OR ITS OFFICERS
OR AGENTS SHALL NOT BE RESPONSIBLE FOR
THE ACCURACY OR COMPLETENESS OF SCANNED
COPIES OF THIS PLAN SHEET.
PREPARED FOR THE
CITY OF SAN LUIS OBISPO
PUBLIC WORKS DEPARTMENT
CM---------
in
BRIDGE NO.
XX-XXXX
POST MILE
26.8 6 D. Polglase
PERMIT DESIGN VEHICLE
LIVE LOADING:
2 75+21.06 BVCElev 153.36
200’ VC
Notes
1. For General Notes, see "Deck Contours" sheet.
1’-9”
CURVE DATA
R=1000.00’A=5* 40’ 43”T=49.59’L=99.11’
PROFILE GRADE
No Scale
For Hydrologic Summary, see "Foundation Plan" sheet. For Utilities, see "Typical Section" sheet.
Dist COUNTY ROUTE
5 SLO US 101 7
30% SUBMITTAL
ROFESS/o,,
/
REGISTERED CIVIL ENGINEER DATE
-2.00% 300’ VC
-3.45% 400’ VC 0.84% s /SCOTT MCCAULEY \
R/C = -0.4849% / Sta
PLANS APPROVAL DATE
R/C = 1.0743% / Sta Exp.
OF CALN
PROFILE GRADE
No Scale Aconsor P: 916.368.9181
BB 250‘—0" Measured along "N" Line EB
125’—0” 125-0” "N" Line
31‘-6" Min & Var
l’-9” 12’ Min & Var 1’-9”
4 J
=
3 PG
7 SR
Abut 1
Approx OG
Bent 2
#
Abut 3
7 7 Ol—
i
Datum Elev = 100.0
31+00 32+00 33+00
DEVELOPED ELEVATION
Approx OG
1” = 20’ A
$
o
CURVE DATA
3) Typ TYPICAL SECTION
1/4” = 1-0”
i - • 3
O
O
"N" Line
33 N 27’04’50” E 32
(
'm
To US 101
"P" Line 4
3 5
CHECKED HL93 W/HLOW—BOY' A. Hanson
CHECKED PRADO ROAD INTERCHANGE
2 A. Hanson
DESIGN OVERSIGHT DETAILS
QUANTITIES
CHECKED
SPECIFICATIONS GENERAL PLAN NO. 4 - ALT 1
T T
I
| REWSION OATES
6/3/26 I I F
T T
FILE A:\_V-TPD\Projects\CA\Son Luis 0bispo\D218721CA.00_Prodo\500-Design\505 - CADD Files\Bridge\D218721d-o-gpO1.dwg I
t
0 48" Dia Conc
Column, Typ-
(1) Paint "US 101 NB On-Ramp”(2) Paint "No. XXX-XXXX”(3) MSE Wall, see "Retaining Wall" sheets (4) Structure Approach Type N (30)
(5) Structure Approach Type N (Mod)
DISREGARD PRINTS BEARING EARLIER REVISION DATES
Conc Barrier
Type 836, Typ
2.3. I I
CIP/PT Conc
Box Girder—
POST MILES
TOTAL PROJECT
26.8/27.3
TOTAL
SHEETS
O
Co0
EUANSAANP SPECS
1 |1
ORIGINAL SCALE IN INCHES
FOR REDUCED PLANS
Scott McCauley
PROJECT ENGINEER
SHEET
No.
C71495
. 12/31/27)CIVIL 7
PLAN
1” = 20’
BB 30+67.50
Elev 158.86
EB 33+17.50Elev 152.43
Note:
The Contractor mst verify all
controlling field dimensions before
ordering or fabricating any material.
"N" 30+00.00 ="P” 51+27.711
CONSOR NORTH AMERICA, INC.2868 PROSPECT PARK DR, STE 250 RANCHO CORDOVA, CA 95670
LOAD & RESISTANCE
FACTOR DESIGN
UNIT: UNITPROJECT NUMBER & PHASE: PROJECT COMBERT NO.: CONTRACT 72” Dia CIDH pile, Typ
42+39.82 BVC
Elev 146.26
SIGN OFF DATEDESIGN DETAIL SHEET (ENGUISH) (REV.7/16/10) 30+75.00 BVCElev 158.71
THE STATE OF CALIFORNIA OR ITS OFFICERS
OR AGENTS SHALL NOT BE RESPONSIBLE FOR
THE ACCURACY OR COMPLETENESS OF SCANNED
COPIES OF THIS PLAN SHEET.
34+43.73 BVCElev 148.15
8‘-0" Min
& Var
33+75.00 EVC
Elev 150.53
mo
38+43.73 EVCElev 142.93
4‘-0" Min
& Var
PREPARED FOR THE
CITY OF SAN LUIS OBISPO
PUBLIC WORKS DEPARTMENT
BRIDGE NO.
XX-XXXX
POST MILE
26.8 R=1200.00’A =13’ 43’ 09”T=144.36’L=287.33’
tO
6 D. Polglase
PERMIT DESIGN VEHICLE
3 LIVE LOADING:
-
2 Notes
1. For General Notes, see "Deck Contours" sheet.
I
.1
I
—31
For Hydrologic Summary, see ’’Foundation Plan" sheet. For Utilities, see "Typical Section" sheet.
Dist COUNTY ROUTE
5 SLO US 101 8
30% SUBMITTAL
ROFESS/o,,
/
REGISTERED CIVIL ENGINEER DATE
-2.00% 300’ VC
-3.45% 400’ VC 0.84% s /SCOTT MCCAULEY \
R/C = -0.4849% / Sta
PLANS APPROVAL DATE
R/C = 1.0743% / Sta Exp.
OF CALN
PROFILE GRADE
No Scale Aconsor P: 916.368.9181
BB 250‘-O" Measured along "N" Line EB
125’—0” 125-0” "N" Line
31‘-6" Min & Var
l’-9” 12’ Min & Var 1’-9”
3 2 PG J SR
L AConc ---
Abut 1
Approx OG
Bent 2
ym
CIP/RC Box Girder
Datum Elev = 100.0
48" Dia Conc
Column, Typ 31+00 32+00 33+00
Approx OG
k----- •:
o
CURVE DATA
3) Typ TYPICAL SECTION
1/4” = 1-0”
i - • 3
O
O
"N" Line
33 N 27’04’50” E 32
(
'm
To US 101
"P" Line 4
3 5
CHECKED HL93 W/HLOW—BOY' A. HansonCHECKED PRADO ROAD INTERCHANGE 2 A. Hanson
DESIGN OVERSIGHT DETAILS
QUANTITIES
CHECKED
SPECIFICATIONS GENERAL PLAN NO. 4 - ALT 2
T T
I
| REWSION DATES
6/3/26 I I
T T
FILE A:\_V-TPD\Projects\CA\Son Luis 0bispo\D218721CA.00_Prodo\500-Design\505 - CADD Files\Bridge\D218721d-o-gpO2.dwg I
t
0 (1) Paint "US 101 NB On-Ramp”(2) Paint "No. XXX-XXXX”(3) MSE Wall, see "Retaining Wall" sheets (4) Structure Approach Type N (30)
(5) Structure Approach Type N (Mod)
DISREGARD PRINTS BEARINGEARLIER REVISION DATES
Conc Barrier
Type 836, Typ
2.3. TOTAL
SHEETS
I I
POST MILES
TOTAL PROJECT
26.8/27.3
O
Co0
EUANSAANP SPECS
1 |1
ORIGINAL SCALE IN INCHES
FOR REDUCED PLANS
Scott McCauley
PROJECT ENGINEER
SHEET
No.
C71495
. 12/31/27)CIVIL 7
PLAN
1” = 20’
BB 30+67.50
Elev 158.86
EB 33+17.50Elev 152.43
Note:
The Contractor mst verify all
controlling field dimensions before
ordering or fabricating any material.
"N" 30+00.00 ="P” 51+27.711
CONSOR NORTH AMERICA, INC.2868 PROSPECT PARK DR, STE 250 RANCHO CORDOVA, CA 95670
LOAD & RESISTANCE
FACTOR DESIGN
UNIT: UNITPROJECT NUMBER & PHASE: PROJECT COMBERT NO.: CONTRACT 72” Dia CIDH
pile, Typ
42+39.82 BVC
Elev 146.26
SIGN OFF DATEDESIGN DETAIL SHEET (ENGUISH) (REV.7/16/10) 30+75.00 BVCElev 158.71
THE STATE OF CALIFORNIA OR ITS OFFICERS
OR AGENTS SHALL NOT BE RESPONSIBLE FOR
THE ACCURACY OR COMPLETENESS OF SCANNED
COPIES OF THIS PLAN SHEET.
34+43.73 BVCElev 148.15
8‘-0" Min
& Var
33+75.00 EVC
Elev 150.53
mo
4’-0” Min
& Var
38+43.73 EVCElev 142.93
PREPARED FOR THE
CITY OF SAN LUIS OBISPO
PUBLIC WORKS DEPARTMENT
BRIDGE NO.
XX-XXXX
POST MILE
26.8 R=1200.00’A =13’ 43’ 09”T=144.36’L=287.33’
tO
6 D. Polglase
PERMIT DESIGN VEHICLE
3 LIVE LOADING:
-
2 Notes
1. For General Notes, see "Deck Contours" sheet.
DEVELOPED ELEVATION
1” = 20’
[HTTP
Abut 3
I
.1
1 —31
For Hydrologic Summary, see ’’Foundation Plan" sheet. For Utilities, see "Typical Section" sheet.
DRAFT
APPENDIX B: 35% Bridge Cost Estimates
7consor
Aconsor
Date 7/2/2026
Prado Road Western Overcrossing CON Year 2030
30% Construction Cost Estimate (Alt 1 - CIP/PT Box Girder) Total
F $ $ 173,250
2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 815 525 427,875 $ $ 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 4160 125 520,000 $ $ 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 64 5,000 320,000 $ $ 5 490616 84" CAST-IN-DRILLED-HOLE CONCRETE PILING LF 720 $ $ 4,500 3,240,000 5 500001 PRESTRESSING CAST-IN-PLACE CONCRETE LS LUMPSUM $ $ 423,100 423,100 6 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 208 1,400 291,200 $ $ 7 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 1565 $ $ 2,600 4,069,000 8 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 900 2,300 $ $ 2,070,000 9 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 215 $ $ 2,000 430,000 10 519100 JOINT SEAL (MR 2") LF 155 225 34,875 $ $
11 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 880016 $ $ 2 1,980,036 12 F 833033 CHAIN LINK RAILING (TYPE 7 MODIFIED) LF 315 500 157,500 $ $ 13 F 833088 TUBULAR HANDRAILING LF 619 300 185,700 $ $
14 F 839719 CONCRETE BARRIER (TYPE 732SW) LF 448 600 268,800 $ $ 15 F 839720 CONCRETE BARRIER (TYPE 732SW MODIFIED) LF 470 750 352,500 $ $ 16 $
17 $
18 $
19 $
20 $
21 999990 MOBILIZATION LS LUMPSUM $ $ 1,660,426
SUBTOTAL CONTRACT $ 16,604,262
SUPPLEMENTAL WORK
22 $
23 $
24 $
SUBTOTAL SUPPLEMENTAL WORK $
Bridge Quantities By: T. Eaton PROJECT SUBTOTAL $ 16,604,262 CONTINGENCY 25% 4,151,066 $
ESCALATION $ 5,636,173
TOTAL $ 26,392,000
1 Bridge Check By: -
Road Quantities By: -
Road Check By: -
Item Code
192003
Unit
cY
Quantity
550
Project. No.
Project Manager
4 Years at
6.19% Per Year
D218721CA.00
B. Lemon
Unit Price
315
Item No. Item Description
STRUCTURE EXCAVATION (BRIDGE)
Aconsor
Date 7/2/2026
Prado Road Western Overcrossing CON Year 2030
30% Construction Cost Estimate (Alt 2 - PC/PS CA Wide Flange Girder) Total
F $ $ 173,250
2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 820 525 430,500 $ $ 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 4160 125 520,000 $ $ 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 64 5,000 320,000 $ $ 5 490616 84" CAST-IN-DRILLED-HOLE CONCRETE PILING LF 720 $ $ 4,500 3,240,000 6 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 208 1,400 291,200 $ $ 7 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 486 $ $ 2,500 1,215,000 8 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 949 2,400 $ $ 2,277,600 9 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 215 $ $ 2,000 430,000 10 512211 FURNISH PRECAST PRESTRESSED CONCRETE WIDE FLANGE GIRDER (140-150') EA 27 $ $ 115,500 3,118,500 11 F 512401 ERECT PRECAST CONCRETE GIRDER EA 27 $ $ 36,750 992,250 12 519100 JOINT SEAL (MR 2") LF 155 225 34,875 $ $
13 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 659262 3 1,648,155 $ $ 14 F 833033 CHAIN LINK RAILING (TYPE 7 MODIFIED) LF 315 500 157,500 $ $ 15 F 833088 TUBULAR HANDRAILING LF 619 300 185,700 $ $
16 F 839719 CONCRETE BARRIER (TYPE 732SW) LF 448 600 268,800 $ $ 17 F 839720 CONCRETE BARRIER (TYPE 732SW MODIFIED) LF 470 750 352,500 $ $ 18 $
19 $
20 $
21 $
22 $
23 999990 MOBILIZATION LS LUMPSUM $ $ 1,739,537
SUBTOTAL CONTRACT $ 17,395,367
SUPPLEMENTAL WORK
24 $
25 $
26 $
SUBTOTAL SUPPLEMENTAL WORK $
Bridge Quantities By: T. Eaton PROJECT SUBTOTAL $ 17,395,367 CONTINGENCY 25% $ 4,348,842
ESCALATION $ 5,904,706
TOTAL $ 27,649,000
1 Bridge Check By: -
Road Quantities By: -
Road Check By: -
Item Code
192003
Unit
cY
Quantity
550
Project. No.
Project Manager
4 Years at
6.19% Per Year
D218721CA.00
B. Lemon
Unit Price
315
Item No. Item Description
STRUCTURE EXCAVATION (BRIDGE)
Aconsor
Date 7/2/2026
Prado Road Eastern Overcrossing CON Year 2030
30% Construction Cost Estimate (Alt 1 - CIP/PT Box Girder) Total
F $ $ 56,700
2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 297 525 155,925 $ $ 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 4160 125 520,000 $ $ 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 64 5,000 320,000 $ $ 5 490616 84" CAST-IN-DRILLED-HOLE CONCRETE PILING LF 480 4,500 2,160,000 $ $ 6 500001 PRESTRESSING CAST-IN-PLACE CONCRETE LS LUMPSUM $ $ 317,300 317,300 7 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 131 1,400 183,400 $ $ 8 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 1158 $ $ 2,600 3,010,800 9 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 682 2,300 1,568,600 $ $ 10 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 231 $ $ 2,000 462,000 11 519100 JOINT SEAL (MR 2") LF 166 225 37,350 $ $
12 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 628239 $ $ 2 1,413,538 13 F 833088 TUBULAR HANDRAILING LF 600 300 180,000 $ $
14 F 839719 CONCRETE BARRIER (TYPE 732SW) LF 300 600 180,000 $ $ 15 F 839720 CONCRETE BARRIER (TYPE 732SW MODIFIED) LF 300 750 225,000 $ $ 16 $
17 $
18 $
19 $
20 $
21 999990 MOBILIZATION LS LUMPSUM $ $ 1,198,957
SUBTOTAL CONTRACT $ 11,989,570
SUPPLEMENTAL WORK
22 $
23 $
24 $
SUBTOTAL SUPPLEMENTAL WORK $
Bridge Quantities By: T. Eaton PROJECT SUBTOTAL $ 11,989,570 CONTINGENCY 25% $ 2,997,392
ESCALATION $ 4,069,755
TOTAL $ 19,057,000
1 Bridge Check By: -
Road Quantities By: -
Road Check By: -
Item Code
192003
Unit
cY
Quantity
180
Project. No.
Project Manager
4 Years at
6.19% Per Year
D218721CA.00
B. Lemon
Unit Price
315
Item No.
1 Item Description
STRUCTURE EXCAVATION (BRIDGE)
Aconsor
Date 7/2/2026
Prado Road Eastern Overcrossing CON Year 2030
30% Construction Cost Estimate (Alt 2 - PC/PS CA Wide Flange Girder) Total
F $ $ 56,700
2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 297 525 155,925 $ $ 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 4160 125 520,000 $ $ 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 64 5,000 $ $ 320,000 5 490616 84" CAST-IN-DRILLED-HOLE CONCRETE PILING LF 480 4,500 2,160,000 $ $ 6 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 130 1,400 182,000 $ $ 7 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 305 2,500 $ $ 762,500 8 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 768 2,500 1,920,000 $ $ 9 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 231 $ $ 2,000 462,000 10 512211 FURNISH PRECAST PRESTRESSED CONCRETE WIDE FLANGE GIRDER (140-150') EA 22 $ $ 110,000 2,420,000 11 F 512401 ERECT PRECAST CONCRETE GIRDER EA 22 35,000 770,000 $ $ 12 519100 JOINT SEAL (MR 2") LF 166 225 $ $ 37,350
13 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 454106 $ $ 3 1,135,265 14 F 833088 TUBULAR HANDRAILING LF 600 300 180,000 $ $
15 F 839719 CONCRETE BARRIER (TYPE 732SW) LF 300 600 180,000 $ $ 16 F 839720 CONCRETE BARRIER (TYPE 732SW MODIFIED) LF 300 $ $ 750 225,000 17 $
18 $
19 $
20 $
21 $
22 999990 MOBILIZATION LS LUMPSUM $ $ 1,276,304
SUBTOTAL CONTRACT $ 12,763,044
SUPPLEMENTAL WORK
23 $
24 $
25 $
SUBTOTAL SUPPLEMENTAL WORK $
Bridge Quantities By: T. Eaton PROJECT SUBTOTAL $ 12,763,044 CONTINGENCY 25% 3,190,761 $
ESCALATION $ 4,332,305
TOTAL $ 20,287,000
1 Bridge Check By: -
Road Quantities By: -
Road Check By: -
Item Code
192003
Unit
cY
Quantity
180
Project. No.
Project Manager
4 Years at
6.19% Per Year
D218721CA.00
B. Lemon
Unit Price
315
Item No.
1 Item Description
STRUCTURE EXCAVATION (BRIDGE)
Aconsor
Date 7/2/2026
Prado Road Interchange Off-Ramp Structure CON Year 2030 30% Construction Cost Estimate (Alt 1 - CIP/PT Box Girder) Total
F $ $ 45,045
2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 306 525 160,650 $ $ 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 2080 125 260,000 $ $ 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 32 5,000 160,000 $ $ 5 490611 72" CAST-IN-DRILLED-HOLE CONCRETE PILING LF 220 $ $ 3,700 814,000 6 500001 PRESTRESSING CAST-IN-PLACE CONCRETE LS LUMPSUM $ $ 139,600 139,600 7 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 93 1,400 130,200 $ $ 8 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 441 $ $ 2,600 1,146,600 9 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 276 $ $ 2,300 634,800 10 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 110 $ $ 2,000 220,000 11 519100 JOINT SEAL (MR 2") LF 79 225 17,775 $ $
12 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 248577 2 559,298 $ $ 13 F 833088 TUBULAR HANDRAILING LF 503 300 150,900 $ $
14 F 839741 CONCRETE BARRIER (TYPE 836) LF 503 350 176,050 $ $ 15 $
16 $
17 $
18 $
19 $
20 999990 MOBILIZATION LS LUMPSUM $ $ 512,769
SUBTOTAL CONTRACT $ 5,127,687
SUPPLEMENTAL WORK
21 $
22 $
23 $
SUBTOTAL SUPPLEMENTAL WORK $
Bridge Quantities By: T. Eaton PROJECT SUBTOTAL $ 5,127,687 CONTINGENCY 25% $ 1,281,922
ESCALATION $ 1,740,549
TOTAL $ 8,151,000
1 Bridge Check By: -
Road Quantities By: -
Road Check By: -
Item Code
192003
Unit
cY
Quantity
143
Project. No.
Project Manager
4 Years at
6.19% Per Year
D218721CA.00
B. Lemon
Unit Price
315
Item No.
1 Item Description
STRUCTURE EXCAVATION (BRIDGE)
Aconsor
Date 7/2/2026
Prado Road Interchange Off-Ramp Structure CON Year 2030 30% Construction Cost Estimate (Alt 2 - CIP/RC Box Girder) Total
F $ $ 45,045
2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 306 525 160,650 $ $ 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 2080 125 260,000 $ $ 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 32 5,000 160,000 $ $ 5 490611 72" CAST-IN-DRILLED-HOLE CONCRETE PILING LF 220 4,500 $ $ 990,000 6 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 93 1,400 130,200 $ $ 7 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 524 $ $ 2,500 1,310,000 8 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 276 $ $ 2,500 690,000 9 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 110 $ $ 2,000 220,000 10 519100 JOINT SEAL (MR 2") LF 79 225 17,775 $ $
11 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 395010 3 987,525 $ $ 11 F 833088 TUBULAR HANDRAILING LF 503 300 150,900 $ $
12 F 839741 CONCRETE BARRIER (TYPE 836) LF 503 350 176,050 $ $ 13 $
14 $
15 $
16 $
17 $
18 999990 MOBILIZATION LS LUMPSUM $ $ 588,683
SUBTOTAL CONTRACT $ 5,886,828
SUPPLEMENTAL WORK
19 $
20 $
21 $
SUBTOTAL SUPPLEMENTAL WORK $
Bridge Quantities By: T. Eaton PROJECT SUBTOTAL $ 5,886,828 CONTINGENCY 25% $ 1,471,707
ESCALATION $ 1,998,233
TOTAL $ 9,357,000
1 Bridge Check By: -
Road Quantities By: -
Road Check By: -
Item Code
192003
Unit
cY
Quantity
143
Project. No.
Project Manager
4 Years at
6.19% Per Year
D218721CA.00
B. Lemon
Unit Price
315
Item No.
1 Item Description
STRUCTURE EXCAVATION (BRIDGE)
Aconsor
Date 7/2/2026
Prado Road Interchange On-Ramp Structure CON Year 2030
30% Construction Cost Estimate (Alt 1 - CIP/PT Box Girder) Total
F $ $ 45,360
2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 334 525 175,350 $ $ 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 2470 $ $ 125 308,750 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 38 5,000 190,000 $ $ 5 490611 72" CAST-IN-DRILLED-HOLE CONCRETE PILING LF 220 $ $ 3,700 814,000 6 500001 PRESTRESSING CAST-IN-PLACE CONCRETE LS LUMPSUM $ $ 176,300 176,300 7 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 102 1,400 142,800 $ $ 8 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 560 $ $ 2,600 1,456,000 9 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 326 2,300 749,800 $ $ 10 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 137 $ $ 2,000 274,000 11 519100 JOINT SEAL (MR 2") LF 99 225 $ $ 22,275
12 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 291172 $ $ 2 655,137 12 F 833088 TUBULAR HANDRAILING LF 504 300 151,200 $ $
13 F 839741 CONCRETE BARRIER (TYPE 836) LF 504 350 176,400 $ $ 14 $
15 $
16 $
17 $
18 $
19 999990 MOBILIZATION LS LUMPSUM $ $ 593,041
SUBTOTAL CONTRACT $ 5,930,413
SUPPLEMENTAL WORK
20 $
21 $
22 $
SUBTOTAL SUPPLEMENTAL WORK $
Bridge Quantities By: T. Eaton PROJECT SUBTOTAL $ 5,930,413 CONTINGENCY 25% 1,482,603 $
ESCALATION $ 2,013,027
TOTAL $ 9,427,000
1 Bridge Check By: -
Road Quantities By: -
Road Check By: -
Item Code
192003
Unit
cY
Quantity
144
Project. No.
Project Manager
4 Years at
6.19% Per Year
D218721CA.00
B. Lemon
Unit Price
315
Item No.
1 Item Description
STRUCTURE EXCAVATION (BRIDGE)
Aconsor
Date 7/2/2026
Prado Road Interchange On-Ramp Structure CON Year 2030
30% Construction Cost Estimate (Alt 2 - CIP/RC Box Girder) Total
F $ $ 45,360
2 F 193003 STRUCTURE BACKFILL (BRIDGE) CY 334 525 175,350 $ $ 3 490528 FURNISH STEEL PILING (HP 14 X 89) LF 2470 $ $ 125 308,750 4 490529 DRIVE STEEL PILE (HP 14 X 89) EA 38 5,000 190,000 $ $ 5 490611 72" CAST-IN-DRILLED-HOLE CONCRETE PILING LF 220 4,500 $ $ 990,000 6 F 510051 STRUCTURAL CONCRETE, BRIDGE FOOTING CY 102 1,400 142,800 $ $ 7 F 510053 STRUCTURAL CONCRETE, BRIDGE CY 655 $ $ 2,500 1,637,500 8 F 510054 STRUCTURAL CONCRETE, BRIDGE (POLYMER FIBER) CY 333 2,500 832,500 $ $ 9 F 510086 STRUCTURAL CONCRETE, APPROACH SLAB (TYPE N) CY 137 $ $ 2,000 274,000 10 519100 JOINT SEAL (MR 2") LF 99 225 $ $ 22,275
11 F 520102 BAR REINFORCING STEEL (BRIDGE) LB 474930 3 1,187,325 $ $ 11 F 833088 TUBULAR HANDRAILING LF 504 300 151,200 $ $
12 F 839741 CONCRETE BARRIER (TYPE 836) LF 504 350 176,400 $ $ 13 $
14 $
15 $
16 $
17 $
18 999990 MOBILIZATION LS LUMPSUM $ $ 681,496
SUBTOTAL CONTRACT $ 6,814,956
SUPPLEMENTAL WORK
19 $
20 $
21 $
SUBTOTAL SUPPLEMENTAL WORK $
Bridge Quantities By: T. Eaton PROJECT SUBTOTAL $ 6,814,956 CONTINGENCY 25% 1,703,739 $
ESCALATION $ 2,313,277
TOTAL $ 10,832,000
1 Bridge Check By: -
Road Quantities By: -
Road Check By: -
Item Code
192003
Unit
cY
Quantity
144
Project. No.
Project Manager
4 Years at
6.19% Per Year
D218721CA.00
B. Lemon
Unit Price
315
Item No.
1 Item Description
STRUCTURE EXCAVATION (BRIDGE)
7consor
APPENDIX C: Geometric Approval Drawings (GAD)
Approval Memo
[PENDING CALTRANS REVIEW]
DRAFT
7consor
APPENDIX D: Approved Bridge Site Data Submittal (BSDS)
[PENDING CALTRANS REVIEW]
7consor
APPENDIX E: Preliminary Bridge Design Hydraulic Study
(BDHS)
F2
mn’s
Canamration beums Sunmer 202% -N sm-e iem rulvdelil" t— US 101 at Prado Road Interchange Project
Project No. 2091613-02 | Caltrans EA 05-1H640
I
J
— poeo
City of San Luis Obispo, California
June 25, 2026
Preliminary Bridge Design
Hydraulic Study
p FUTURE LOCATION OF THE
- PRADO INTERCHANGE
F?
Executive Summary
June 25, 2026 | i
The scour potential was evaluated for the proposed bridges using the scour design flood, which is the 100-year flow, and the scour check flood, which is the 200-year flow. Long-term bed elevation changes (degradation) are typically based on historical data at the bridge site. Bridge Inspection Reports do not exist at the Project, and long-term bed elevation change was not assessed for the Preliminary Bridge Design Hydraulic Study
US 101 at Prado Road Interchange Project
This Bridge Design Hydraulic Study focuses on the new bridges at US 101 NB off-ramp to Prado Road, US 101 NB on-ramp from Prado Road, the Prado Road west overcrossing, and the Prado Road east overcrossing, which are located within the floodplain of San Luis Obispo Creek. The purpose of this Bridge Design Hydraulic Study is to present the design flow characteristics for San Luis Obispo at the Project site, the hydraulic characteristics associated with the pre-Project (existing condition) and post-Project (proposed condition), and the scour potential for the proposed condition.
The proposed bridge design was provided by Consor Engineers and the geotechnical data used for the scour analysis were provided by Yeh and Associates, Inc.
The proposed U.S. Route 101 (US 101) at Prado Road Interchange Project (Project) includes improvements to extend Prado Road over US 101 to connect with Dalidio Drive, reconstruct the existing US 101 northbound (NB) off-ramp and on-ramp connections with Prado Road, and construct an auxiliary lane on NB US 101 between the Prado Road and Madonna Road interchanges in order to provide congestion relief, operational efficiency, and multimodal connectivity. The interchange is located in the city of San Luis Obispo in the county of San Luis Obispo at Post Mile (PM) 26.8 and improvements on NB US 101 extend from PM 26.5 to PM 27.3. The preferred alternative includes a partial interchange with the proposed Prado Road overcrossing constructed over US 101, a new US 101 NB off-ramp to Prado Road, and a new NB on-ramp from Prado Road.
The 200-year, 100-year, and 50-year recurrence interval design flows for the Project are based on data from the Federal Emergency Management Agency and calculated using United States Geological Survey equations. A two-dimensional (2D) model was developed for the Project to assess the existing and proposed conditions using the design flows. Grading for the Project was provided by Consor Engineers and was used to develop the proposed condition model.
Comparison rasters were generated in the hydraulic model to calculate the differences in water surface elevation (WSE) between the proposed and existing conditions. There are localized increases and decreases in WSE within the vicinity of the Project improvements. During the 100- year storm event, the maximum increase in WSE is 2.4 feet (ft), and it occurs at the upstream corner of the western abutment (Abut 1) at the Prado Road west overcrossing bridge. During the 50-year storm event, the maximum increase in WSE is 1.9 ft, and it also occurs at the upstream corner of the western abutment (Abut 1) at the Prado Road west overcrossing bridge.
The applicable freeboard criteria for the Project require that the bridges pass the 100-year flow without freeboard and the 50-year flow with 2 ft of freeboard. Based on the results of the hydraulic analysis, the Project bridges will meet the freeboard requirements.
Cross section lines were used to extract data from the 2D model results. The WSEs were extracted along the upstream faces of the Project bridges. The maximum WSEs were extracted, and an average of WSEs along the line were also estimated. The maximum WSE in the proposed condition compared with the maximum WSE in the existing condition increases by 0.1 ft or less. The average WSE in the proposed condition compared with the average WSE in the existing condition increases by 0.3 ft or less.
ii | June 25, 2026
Preliminary Bridge Design Hydraulic Study
US 101 at Prado Road Interchange Project
Project. Based on the scour analysis for the design flood, the contraction scour depths range from 0 to 1.7 ft depending on support location, and the local scour depths range from 1.4 to 11.0 ft depending on the support location. The associated long-term scour elevation for the design flood ranges from 127.2 ft North American Vertical Datum of 1988 (NAVD 88) to 133.0 ft NAVD 88. Based on the scour analysis for the check flood, the contraction scour depths range from 0 to 2.1 ft depending on support location, and the local scour depths range from 2.1 to 13.0 ft depending on the support location. The associated long-term scour elevation for the check flood ranges from 126.9 to 133.0 ft NAVD 88. The foundations are required to be designed to withstand the effects of scour with pile resistance accounting for potential material loss due to scour.
F2
Contents
Executive Summary i
1 General Description
1.5 Vertical Datum
2 Geographic Setting
3 Hydrologic Assessment 13
4 Hydraulic Analysis
4.3 Hydraulic Model Results
5 Scour Analysis
6 References 47
Tables
June 25, 2026 | iii
Geographic Location...
Watershed Description
Design Tools...........................
Hydraulic Model Development
Preliminary Bridge Design Hydraulic Study
US 101 at Prado Road Interchange Project
10 10
10 2.1
2.2 4.2.1
4.2.2 4.2.3
4.2.4 4.1
4.2 4.3.1
4.3.2 4.3.3
1.4.1 1.4.2
1.4.3 1.1
1.2 1.3
1.4 5.1
5.2 5.3
5.4 5.5
5.6 5.7
15 15
15 15
15 17
21 23
26 36
37 40
40 41
41 41
42 43
44 1
1 1
1 7
7 8
9 9
Project Description
Study Purpose......
Key Tasks.............
Design Criteria......
11 13
17 20
Hydraulic Design Criteria
Foundation Criteria........
Scour Design Criteria.....
Water Surface Elevations
Freeboard.......................
Flow Velocities................
Caltrans Bridge Inspection Reports
Existing Channel Bed.....................
Long-Term Bed Elevation Change..
Contraction Scour...........................
Pier Scour.......................................
Abutment Scour..............................
Total Scour......................................
Computational Grid/2D Flow Areas.............
Model Boundary Conditions.........................
Existing Condition Geometry.......................
Proposed Condition Geometry Adjustments
Table 1. Watershed Drainage Areas.......................................................
Table 2. Hydrologic Data Summary for Project.......................................
Table 3. Data Sources Used to Develop the Hydraulic Model Geometry Table 4. Manning's n Values....................................................................
Figures
iv | June 25, 2026
Preliminary Bridge Design Hydraulic Study
US 101 at Prado Road Interchange Project
23 34
34 35
35 35
36 36
36 40
42 43
44 44
44 45
45 45
45 46
46 ..2
..3
..4
..5
..6
11 12
16 19
22 24
25 26
28 29
30 31
32 33
38 39
Table 5. River Stations along San Luis Obispo Creek at Geographical Locations.
Table 6. 100-year Water Surface Elevations Upstream of Bridges........................
Table 7. 50-year Water Surface Elevations Upstream of Bridges..........................
Table 8. Hydrologic Summary Table for Prado Road West Overcrossing.............
Table 9. Hydrologic Summary Table for Prado Road East Overcrossing..............
Table 10. Hydrologic Summary Table for US 101 NB Off-Ramp...........................
Table 11. Hydrologic Summary Table for US 101 NB On-Ramp...........................
Table 12. 100-Year Water Surface Elevations and Freeboard..............................
Table 13. 50-Year Water Surface Elevations and Freeboard................................
Table 14. Summary of Structures within Floodplain and Type of Scour Assessed Table 15. Calculated Contraction Scour Depths....................................................
Table 16. Calculated Local Pier Scour Depths.......................................................
Table 17. Calculated Local Abutment (and MSE Wall) Scour Depths...................
Table 18. Scour Summary Table: Prado Road West Overcrossing.......................
Table 19. Scour Summary Table: Prado Road East Overcrossing........................
Table 20. Scour Summary Table: US 101 NB Off-Ramp.......................................
Table 21. Scour Summary Table: US 101 NB On-Ramp.......................................
Table 22. Scour Data Table: Prado Road West Overcrossing...............................
Table 23. Scour Data Table: Prado Road East Overcrossing................................
Table 24. Scour Data Table: US 101 NB Off-Ramp...............................................
Table 25. Scour Data Table: US 101 NB On-Ramp...............................................
Figure 1. Project Location Map...........................................................................................
Figure 2. Project Vicinity Map.............................................................................................
Figure 3. Proposed Prado Road Interchange Bridges General Plan.................................
Figure 4. Proposed US 101 NB Off-Ramp Bridge General Plan........................................
Figure 5. Proposed US 101 NB On-Ramp Bridge General Plan........................................
Figure 6. San Luis Obispo Creek Watershed Map.......................................................
Figure 7. Project Watershed Map.......................................................
Figure 8. 2D Flow Areas and Boundary Conditions.......................................................
Figure 9. Bridges as SA/2D Connections in Hydraulic Model............................................
Figure W.Terrain Comparison in Vicinity of Project.......................................................
Figure 11. Location of Profile Used to Summarize Model Results.....................................
Figure 12. Locations of Cross Sections Used to Summarize Model Results.....................
Figure 13. Existing Condition 100-year Flow Depths.......................................................
Figure 14. Existing Condition 100-year Flow Depths at Project Vicinity............................
Figure 15. San Luis Obispo Creek 100-Year Water Surface Profile within Model Domain Figure 16. San Luis Obispo Creek 50-Year Water Surface Profile within Model Domain..
Figure 17. Changes in WSE within the 2D Model Domain.................................................
Figure 18. 100-year WSE Comparison (Proposed - Existing) within Project Vicinity.........
Figure 19. 50-year WSE Comparison (Proposed - Existing) within Project Vicinity...........
Figure 20. Changes in Velocities within the 2D Model Domain.........................................
Figure 21. 100-year Velocity Comparison (Proposed - Existing) within Project Vicinity....