Technical Memorandum
Advanced Mobility Group | 3003 Oak Rd, Suite 100, Walnut Creek, CA 94597 www.amobility.com
To:
Mary Bean
Director, Professional Services
FirstCarbon Solutions
From: Christopher Thnay, PE, AICP
Address: Walnut Creek, California 94597
Email: [email protected] Date: December 7, 2023
Subject: Estimated Trip Generation of Sperry Commercial 2 Project, Patterson, CA Introduction
This brief technical memorandum summarizes the results of a trip generation conducted located to the southwest corner of the intersection of Sperry Avenue and Haggerty Way, Patterson, CA as shown in Figure 1. The proposed project consists
primarily of approximately 13.3 acres.
The purpose of this tech memo is to document results
of our review if the estimated project trips exceeded
the total trips previously approved in the certified
2003 West Patterson Business Park EIR. The
proposed project land use consists of approximately
94,394 sf of commercial and restaurant land use.
AMG will determine if projected trips would result in
additional traffic than the previously approved R&D
land use in the EIR.
Trip Generation Estimate
The proposed Sperry Commercial Park 2 Project site
was approved as a part of the 2003 West
Patterson Master Plan as shown in Figure 2. The
assumed land use was Research and Development
(R&D). The trip generation for the originally
approved 2002 West Patterson Master Plan was
based on the zoning and model trips rates that were assumed at that time.
The proposed Sperry Commercial Park 2 Project site was located within the Traffic Analysis Zones (TAZ) 4 (approximately 171.3 acres) of the model used in the 2002 West Patterson Master Plan.
According to the Baldwin Ranch Project Traffic Impact Study1, the total acreage of two projects within TAZ 4 which were previously approved (Palm Plaza and Baldwin Ranch) were 1 Traffic Impact Study for the Proposed the Proposed Baldwin Ranch Project, City of Patterson, CA, September 11, 2020 Figure 1: Site Plan
December 7, 2023
Mary Bean
approximately 84 percent of the total 171.3 acre in TAZ 4. The Baldwin Ranch Project report indicated a net reduction in trips based on the two previously approved projects.
The first task is to determine the total trips generated by the proposed 94,394 sf Sperry Commercial Park 2 development. AMG would
then compare the total trips generated by all
three developments (Palm Plaza, Baldwin Ranch
and Sperry Commercial Park 2) contained in TAZ
4 (171.3 acre) to the originally approved trips in
the 2002 West Patterson Master Plan.
Typically, the peak hour trip generation for a
project are estimated based on the Trip
Generation Manual, 11th Edition, published by
the Institute of Transportation Engineers (ITE).
AMG used various categories included in the ITE
Manual for the 13 proposed developments
shown in the site plan as shown in Appendix A.
The proposed Sperry Commercial Park 2
development consisted of approximately 94,394 square feet (sf) of retail and services related land uses. The breakdown is shown in Table 1 with key uses summarized below:
• Retail
• Office
• Grocery
• Shushi Restaurant
• Shoe Store
• Pet Supply
• Fastfood
• Car Wash
• Gas/MiniMart
• Coffee Shop
The ITE trip-generation data and analysis methods apply primarily to single-use and freestanding sites, which limits their applicability to compact, mixed-use development. In 2011, two major studies introduced methodologies for predicting traffic generation from mixed use development:
i. National Cooperative Highway Research Program (NCHRP) Report 684, “Enhancing Internal Trip Capture Estimation for Mixed- Use Developments,” analyzed internal-capture relationships of mixed-use sites and examined the travel interactions among six individual types of land uses: office, retail, restaurant, residential, cinema, and hotel, and ii. The U.S. EPA–sponsored 2011 report, “Traffic Generated by Mixed-Use Developments — A Six-Region Study Using Consistent Built Environmental Measures,” investigated trip generation, mode choice, and trip length for trips produced and attracted by mixed use developments.
Figure 2: TAZ of 2002 West Patterson Master Plan
December 7, 2023
Mary Bean
Researchers selected six regions — Atlanta, Boston, Houston, Portland, Sacramento, and Seattle — to represent a wide range of urban scale, form, and climatic condition. It was concluded that the ITE Trip Generation Manual and Handbook overestimate peak traffic generation for mixed-use development by an average of 35 percent.[2] For this project, AMG assumed that approximately 20 percent of trips are internal trips by residents who might be customers for various retail shops, restaurant and other businesses.
Table 1: Proposed Project Trip Generation
For this study, pass-by trip reduction was applied. These trips, known as Pass-By trips, do not result in a route deviation for the existing vehicles as these vehicles are already traveling on a route that provides direct access to the project site. Therefore, these trips result in increased driveway traffic for the project site but do not result in an increase of traffic traveling through the network. Without applying the Pass-By reduction, the trip estimation would effectively double count trips which are attributed to these vehicles.
The ITE estimated Pass-By trips were available for shopping centers, fast-food, restaurant, coffee shop, grocery, and gas/minimart. The percentages of ITE pass-by trips used are listed in Table 1.
Taking into consideration pass-by trips, it is estimated that the project will generate approximately 218 and 406 new trips respectively during the AM and PM peak hours. [2] NCHRP Report 684, “Enhancing Internal Trip Capture Estimation for Mixed- Use Developments,”2011, page 26 Rate In Out Total Rate In Out Total
1 Shoe Store ITE 820 19.20 ksf 0.94 12 7 19 3.81 36 38 74 2 Shushi Restauraunt ITE 931 4.56 ksf 0.73 2 2 4 7.80 24 12 36 3 Fastfood ITE 934 5.00 ksf 44.61 114 110 224 33.03 86 80 166 4 Car Wash A ITE 948 4.76 ksf 0 0 0 14.20 34 34 68
5 Gas/MiniMart ITE 944 12 pump 10.28 62 62 124 13.91 84 84 167 6 Coffee Shop ITE 938 4.10 ksf 39.81 84 80 164 15.08 31 31 62 7 Fastfood ITE 934 4.10 ksf 44.61 93 90 183 33.03 71 65 136 8 Fastfood ITE 934 4.10 ksf 44.61 93 90 183 33.03 71 65 136 9 Grocery ITE 850 14.04 ksf 3.82 32 22 54 9.24 66 64 130 10 Pet Supply A ITE 866 11.91 ksf 0 0 0 3.55 21 22 43
11 Retail ITE 820 4.96 ksf 0.94 3 2 5 3.81 9 10 19
12 Office ITE 712 6.99 ksf 1.67 10 2 12 2.16 5 11 16
13 Office ITE 712 6.99 ksf 1.67 10 2 12 2.16 5 11 16
Total 94.39 515 469 984 543 527 1,069
Shopping Center B ITE 820 - - - -34% -15 -16 -31
Fastfood B ITE 934 -50% -150 -145 -295 -55% -125 -116 -241 Restaurant B ITE 931 0% 0 0 0 -44% -8 -8 -16
Coffee Shop B ITE 938 -90% -103 -99 -202 -98% -32 -29 -61 Grocery B ITE 950 0 0 0 -24% -16 -15 -31
Gas/MiniMart B ITE 944 -58% -37 -35 -72 -42% -36 -34 -70 -290 -279 -569 -232 -218 -450
- - -20% -103 -94 -197 -20% -109 -105 -214
122 96 218 202 204 406
Parcel
# Land Use ITE Code Size
A.M. Peak P.M. Peak
Pass-By Reductions
Sub-Total
Internal Trip Reduction C
20% Internal Trip Assumption
Total New Trips
Note:
A - No AM info provided
B - Pass-By through ITE
C - Internal trips of 20 % used (NCHRP 684) - lower than 30% or more shown in NCHRP 684 or EPA Study ITE Source: ITE Trip Generation Manual 11th Edition, 2022; Pass-By - ITE Handbook 2021;ITE 820 based on TripGenHandbook_3rdEdition_Sep2017
December 7, 2023
Mary Bean
Determine Incremental Difference in Trip Generation
As indicated earlier, the proposed Sperry Commercial Park 2 development project site was approved as a part of the 2003 West Patterson Master Plan as shown in Figure 2. The assumed land use was Research and Development (R&D)
The trip generation for the originally approved 2002 West Patterson Master Plan was based on the zoning and model trips rates that were assumed at that time. TAZ 4 is approximately 171.3 acres. The trip generation estimates for approximately 1.7 ksf R&D were approximately 1,651 and 1,786 trips during the AM and PM peak hours for the site contained in TAZ 4.
The Palms Plaza project that will occupy 12.29 acre of the southwest quadrant of the intersection of Baldwin Road/Sperry Drive is expected to generate approximately 291 and 289 trips during the AM and PM peak hours.2 The Baldwin Ranch is approximately 131.4 acre and estimated to generate approximately 552 and 1,076 trips during the AM and PM peak hours. The total acreage of Palm Plaza and Baldwin Ranch would be approximately 84 percent of the total 171.3 acre in TAZ 4.
Compared to the originally approved 2002 West Patterson Master Plan project, it is estimated that the incremental trip difference due to the proposed Sperry Commercial Park 2 development project and the rest of proposed projects in TAZ 4 when compared to the previously assumed land use in TAZ 4 is shown in Table 2.
Table 2: Incremental Difference Project Trip Generation In summary, after prorated based on the project acreage, the total of proposed projects in TAZ 4 (including Sperry Commercial Park 2, Baldwin Ranch project and Palms Plaza) would generate 558 less trips during the AM peak hour and 14 less trips during the PM peak hour based on new trips generated compared with the originally approved 2002 West Patterson Master Plan project. Detailed information of the 2002 West Patterson Master Plan land use and trip generation assumption are shown in Appendix B.
z:\p2310371 - sperry commercial park 2 project (fcs)\07 report\tm 120723 sperry comm # 2 trip gen.docx 2 Traffic Impact Study for Proposed Palms Plaza Development in Patterson, CA, December 14, 2018 TAZ AM Peak Hr Trips PM Peak Hr Trips Acreage
4 1,651 1,786 171.3
Approved Palms Plaza Trips 291 289 12.29
Approved Baldwin Ranch Trips 552 1,076 131.4
Estimated Sperry Commercial #2 218 406 18.42
Total Sperry Commercial #2, Palms Plaza
& Baldwin Ranch 1061 1771 162.11
Net New Trips (Prorated) -558 -14
W Patterson Master Plan EIR (2002)
Advanced Mobility Group | 3003 Oak Rd, Suite 100, Walnut Creek, CA 94597 www.amobility.com
Appendix A
Site Plan
Advanced Mobility Group | 3003 Oak Rd, Suite 100, Walnut Creek, CA 94597 www.amobility.com
Appendix B
2002 West Patterson Master Plan Land Use and Trip Generation Assumption Keystone Pacific
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