So. Linden Ave. & Scott St. Grade Separation (LSGS) Project Preliminary Design Refinements
Presentation to City Council
August 12, 2026
Agenda
1. Project overview and history
2. Design refinement update
3. MOU amendment request
2 Project Location
South San Francisco Station
Colma Creek
N
San Bruno Station
City Limit SSF and SB
Scott St
1,850 feet
to San Francisco
to San Jose
South Linden Ave
Southline
Development
I-380
UPRR/
Granite Rock
Airport Blvd
San Bruno Ave
3 Catrain Tracks
4 Alt South Linden Avenue Scott Street
PSR-Alt1 ▪ Rail Elevated
▪ Roads Lowered
▪ Rail Elevated
▪ Road Closed
▪ Ped/Bike Tunnel
OA ▪ Rail At-Grade
▪ Roads Fully Lowered
▪ Rail At-Grade
▪ Road Closed
▪ Ped/Bike Tunnel
Value Engineering (VE)– Optimized Alternative
Jacked (push) Boxes Beneath Railroad
Optimized Alternative (OA) Selected by Caltrain and Cities in Feb. 2025 Project Schedule
Project Activities Start Date Expected
Completion
Updated Preliminary Engineering/Environmental
Clearance Schedule (35% design)
Feb 2026 May 2027
Jacked Box - OA Design Refinements (DRs)
1. Key Project Goal – separate vehicles, bikes, peds from railroad tracks
2. Jacked Box OA is now in Design Refinement (DR) Stage
3. Additional and updated key information plus feedback incorporated ✓ Forecasted traffic increases roadway (vehicles, ped/bike) and trains ✓ Applicable Caltrain, City and State standards and plans (e.g. ADA) ✓ Feedback from key stakeholders (City, Caltrain, Southline, Utilities) ✓ Property and business impacts (e.g. Southline)
✓ Constructability, Affordability (reduce box size and project footprint)
4. Outcome of DR process will allow project to confidently advance to 35%
5 Design Refinement (DR) Matrix
DR
#
Key Project Design Element Considered Box Size Notes/Decision 1 OA Base Design
• Rail elevated 2 ft, road lowered 20 ft.
• Box sized to support 2 tracks and a 15-ft
Caltrain maintenance road
• 1 WB & 2 EB lanes at S. Linden Ave at RR Box
• Elevated bicycle & pedestrian paths at both
sides of RR Box Structure
• Bicycle lane and pedestrian sidewalk at same
grades as adjacent roadway along lowered
Southline Ave
• 5% roadway slope on Southline Ave
• Ramp to Scott Underpass – full take of AT&T
parcel
84x23x60
(115,920)
• Major impacts to Southline (steep driveways
and no sidewalk to bldgs.)
• Major impacts to other nearby businesses.
• New traffic analysis shows need for 2 WB &
2EB lanes.
• Current 1 WB & 2 EB is not acceptable.
6 Design Refinement (DR) Matrix
DR# Key Project Design Element Considered Box Size Notes/Decision 2A • Removal of 15’ wide Caltrain Maintenance Road
adjacent to one side of RR Tracks
84x23x45
(86,940)
• Reduced size of box width acceptable. RECOMMENDED
2B • Min. lane configuration (1WB & 1EB) at S. Linden 60x23x45 (62,100)
• Eliminated per SSF, due to single EB WB Lane.
2C • Separates Sidewalk and Bike paths at Southline,
Pedestrian Overpass, 1 WB & 2 EB lane at S.
Linden Ave
60x23x45
(62,100)
• Addresses Southline impacts.
• Does not address traffic capacity at 1 EB & 2 WB lanes. • Eliminated by SSF due to 1 WB & 2 EB not acceptable
2D • Pedestrian overpasses & improved lane
configuration at S. Linden Ave with (2 WB & 2 EB
lanes). Shared 13 ft bike/ped path on N. side and
5.5 ft sidewalk on S. Side. 0 ft track raise.
82x23x41
(77,326)
• Best compromise for Southline, Traffic, Safety, Bike/Ped, Reduced Footprint, Affordability. RECOMMENDED.
3 • Track Raise with OCS Replacement n/a • No track raise RECOMMENDED. To be discussed and revisited during next phase of design.
4 • Dollar/Linden/Southline Grade Separation 60x23x45 • Eliminated per SSF due to impacts to traffic. 5 • Use of Petrucco Verona System 84x23x60 • Eliminated per SSF due to impacts to roadway and driveway.
6 • Box Jacking from West to East n/a • Constructability improvement. 7 • Scott Underpass – Only partial take of AT&T
parcel
26x18x60 • Under consideration by San Bruno.
• Reduces footprint. Parking impacts being considered.
7 Traffic Analysis with Grade Separation
Forecasted Vehicle Traffic Volume Increase of 400%
Conclusions - 2EB & 2 WB lanes on S. Linden E of RR Tracks to San Mateo Required.
Pedestrian Bridge over Very Busy/Congested Southline/Dollar Intersection Highly Desirable • Refinement 1 – Longest queues; WB South Linden and SB Dollar are primary constraints. • Refinement 2C – Shorter queues than 1 due to more green time, but queues remain substantial. • Refinement 2D – Best performance; two WB lanes substantially reduce projected queues. RECOMMENDED 8 Caltrain
CaltrainCaltrain
Refinement 1
DR 2D Rendering – Pedestrian Overpass with 2 WB Lanes
9 S. Linden Ave Bike/Ped
Bridges
(18’ VC)
Building B6
Building B7
Parking Garage
Multi-use
path
Sidewalk
Drwy Lowered
2D
Design
Refine.
Lowere
d
1 Base
Design
A/H 0 2.6’
E 1.6’ 1.2’
F 0.4’ 0.3’
G 0 6.0
C 0.5 3.8
B 0.6 1.3
Bike/Ped
Shared Path
16.5’
G
C
F
DR- 2D Rendering – Street/Sidewalk
10 Shared ped/bike
Bridge
From View Facing East From Southline Bldgs
Shared ped/bike
Bridge
DR - 2D Rendering – Multi-use Ped/Bike Path and Bridge
11 Shared ped/bike
Bridge
12 • Additional PE/ENV funds are needed to complete current design phase ✓ Project management budget for the extended schedule during Value Engineering task ✓ Alternative development activities from performed between 2023 to 2025 ✓ Optimized Alternative requires additional technical studies
MOU AMENDMENT
13 Proposed Project Funding
Phase SMCTA
Measure A
Grade
Separation
SMCTA
Measure A
Caltrain
South San
Francisco
San Bruno Total
Original PE/ENV Cost $4,950,000 $0 $386,650 $163,350 $5,500,000 Additional PE/ENV Costs $2,804,490 $860,625 $804,408 $176,577 $4,646100 Total PE/ENV Costs $7,754,490 $860,625 $1,191,058 $339,927 $10,146,079 • SMCTA May Board Approval Resolution 2026-13: Program and Allocate $2,804,490 in Measure A Grade Separation Category and $860,625 Measure A Caltrain Category Funds for the required work.
14 • City of South San Francisco will contribute an additional $804,408 for the South Linden Avenue/Scott Street Grade Separation Project’s Preliminary Engineering and Environmental Clearance Phase.
✓ SMCTA (Measure A) - $2,804,490
✓ Caltrain (Measure A) - $860,625
✓ City of South San Francisco - $804,408
✓ City of San Bruno - $176,577
SSF Staff Recommendation
Preliminary Design Refinements
Presentation to City Council
August 12, 2026
City of South San Francisco
THANK YOU