APPENDIX H
TRANSPORTATION IMPACT STUDY
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490 Mendocino Avenue, Suite 201 Santa Rosa, CA 95401 707.542.9500 w-trans.com SANTA ROSA • OAKLAND
November 24, 2025
Ms. Amber Sharpe
Placeworks
2040 Bancroft Way, Suite 400
Berkeley, CA 94704
Transportation Impact Study for the Yountville Commons Project Dear Ms. Sharpe;
W-Trans has completed the evaluation of potential transportation impacts associated with the Yountville Commons Project to be located on the northeast corner of Yount Street/Finnell Road in the Town of Yountville.
The purpose of this letter is to set forth the project’s trip generation, potential impacts under the guidance of the California Environmental Quality Act (CEQA), and effect on traffic operations.
Project Description
The Yountville Commons Project would be located on the northeast corner of Yount Street/Finnell Road and consist of up to 150 multi-family units, distributed across 15 three-story buildings. The proposed units would primarily be designated for residents that work within the Town, and all are being designed to be affordable for the Town’s workforce. The project would also include up to 1,500 square feet of food-oriented commercial space on the ground floor of the three multi-family buildings on the southern portion of the site and up to 1,500 square feet of other local-serving businesses such as dog grooming and training services as well as up to 8,000 square feet of civic and commercial space in three two-story buildings along Yount Street that would accommodate potential uses such as a town archive and small local-serving businesses. Vehicle parking would be accommodated in a parking lot and bike parking facilities would also be provided.
A portion of the site was previously occupied by the Yountville Elementary School, which closed in 2020. Other uses that exist and would be retained include Town Hall, a dog park, a fitness center, a community hall in the school’s multi-purpose room, a Farmstand Garden and a café and farmstand in the athletic field snack shack.
Trip Generation
The anticipated trip generation of the proposed project was estimated using standard rates published by the Institute of Transportation Engineers (ITE) in Trip Generation Manual, 12th Edition, 2025. Although the site is not located near rail transit, because of the preference to local workers who would not need to drive to work, rates for “Multifamily Housing (Low-Rise) Close to Rail Transit” (ITE LU #220) were used for the residential units. This rate captures the trips for residents who work outside the Town and commute to work. Rates for a “Strip Retail Plaza” (ITE LU #822) were applied to the commercial space given the broad variety of both retail and service uses that are accommodated by this land use category.
ITE also provides guidance to determine the number of trips that would be internally captured – or those made between new residences and new commercial enterprises and therefore not contribute to traffic on the surrounding roadway network. While no internal capture would be anticipated during the morning peak hour given the relatively low volumes projected, an average of 19 percent internal capture would be anticipated during the evening peak hour as shown on the enclosed spreadsheet. This rate was applied to the lower of the trip generations for the two land uses, and then the corresponding number of trips was deducted from the other land use as one internally-captured trip results in two fewer trip ends – one from the generating land use and one from the receiving land use.
Ms. Amber Sharpe Page 2 November 24, 2025
Based on the application of these assumptions, the proposed project is expected to generate an average of 1,079 net new trips per day, including 72 a.m. peak hour trips and 111 trips during the p.m. peak hour. These results are summarized in Table 1.
Table 1 – Trip Generation Summary
Land Use Units Daily AM Peak Hour PM Peak Hour
Rate Trips Rate Trips In Out Rate Trips In Out
Multifamily Residential 150 du 4.72 708 0.30 45 13 32 0.45 68 40 28 Internal Capture n/a -114 n/a 0 0 0 -19% -13 -8 -5
Strip Retail Plaza 11.0 ksf 54.45 599 3.93 43 24 19 6.29 69 35 34 Internal Capture -19% -114 n/a 0 0 0 n/a -13 -5 -8
Net New Trips 1,079 88 37 51 111 62 49
Note: du = dwelling unit; ksf = 1,000 square feet
Trip Distribution
The pattern used to allocate new project trips to the street network was determined by reviewing employment patterns for residents of the Town of Yountville as indicated by the 2000 Census as well as based on knowledge of the local circulation system. The assumptions shown in Table 2 were applied.
Table 2 – Trip Distribution Assumptions
Route Percent
To/from the south via SR-29 40%
To/from the north via SR-29 35%
Within Yountville 25%
TOTAL 100%
Study Area and Periods
The study consists of the following intersections. Conditions during the weekday a.m. and p.m. peak periods were evaluated.
1. Yount Street/Madison Street
2. Yount Street/Finnell Road
3. Yount Street/Washington Street
Yount Street/Madison Street is a three-legged intersection with all approaches stop controlled. Crosswalks exist on the south and west legs.
Yount Street/Finnell Road also has three legs and all-way stop controls. There are crosswalks on the east and south legs.
Yount Street/Washington Street is an all-way stop-controlled intersection with three public street legs and one driveway leg, with crosswalks on all legs.
Ms. Amber Sharpe Page 3 November 24, 2025
Vehicle Operation/Policy Issues
Operational Standard
The Yountville General Plan indicates that LOS C shall be the minimum Level of Service maintained at all intersections.
Existing Conditions
The Existing Conditions scenario provides an evaluation of current operation based on existing traffic volumes during the a.m. and p.m. peak periods. This condition does not include project-generated traffic volumes. Volume data was collected October 7, 2025, while local schools were in session. Under existing volumes, all studied intersections operate at LOS A. A summary of the intersection Level of Service calculations is contained in Table 3, and copies of the calculations for all scenarios are enclosed.
Table 3 – Existing Peak Hour Intersection Levels of Service Study Intersection
Approach
AM Peak PM Peak
Delay LOS Delay LOS
1. Yount Street/Madison Street 7.6 A 7.5 A
2. Yount Street/Finnell Road 7.4 A 7.3 A
3. Yount Street/Washington Street 8.7 A 8.1 A
Notes: Delay is measured in average seconds per vehicle; LOS = Level of Service Future Conditions
Segment volumes for the horizon year of 2045 were developed using an assumed one percent per year growth rate for 20 years, resulting in the existing volumes being multiplied by a factor of 1.22. Under the anticipated future volumes, the study intersections are expected to all operate at LOS A. Future operating conditions are summarized in Table 4.
Table 4 – Future Peak Hour Intersection Levels of Service Study Intersection
Approach
AM Peak PM Peak
Delay LOS Delay LOS
1. Yount Street/Madison Street 7.7 A 7.5 A
2. Yount Street/Finnell Road 7.6 A 7.4 A
3. Yount Street/Washington Street 8.8 A 8.3 A
Notes: Delay is measured in average seconds per vehicle; LOS = Level of Service Existing plus Project Conditions
Upon adding project-related traffic to the existing volumes, all the study intersections are expected to continue operating at LOS A. These results are summarized in Table 5.
Ms. Amber Sharpe Page 4 November 24, 2025
Table 5 – Existing and Existing plus Project Peak Hour Intersection Levels of Service Study Intersection Existing Conditions Existing plus Project AM Peak PM Peak AM Peak PM Peak
Delay LOS Delay LOS Delay LOS Delay LOS
1. Yount Street/Madison Street 7.6 A 7.5 A 7.7 A 7.6 A
2. Yount Street/Finnell Road 7.4 A 7.3 A 7.6 A 7.6 A
3. Yount Street/Washington Street 8.7 A 8.1 A 9.0 A 8.4 A Notes: Delay is measured in average seconds per vehicle; LOS = Level of Service Future plus Project Conditions
Similarly, upon adding project-generated trips to future volumes, every study intersection is expected to continue operating at LOS A. These results are shown in Table 6.
Table 6 – Future and Future plus Project Peak Hour Intersection Levels of Service Study Intersection Future Conditions Future plus Project AM Peak PM Peak AM Peak PM Peak
Delay LOS Delay LOS Delay LOS Delay LOS
1. Yount Street/Madison Street 7.7 A 7.5 A 7.8 A 7.6 A
2. Yount Street/Finnell Road 7.6 A 7.4 A 7.8 A 7.6 A
3. Yount Street/Washington Street 8.8 A 8.3 A 9.1 A 8.6 A Notes: Delay is measured in average seconds per vehicle; LOS = Level of Service Finding – The study intersections are expected to operate acceptably under all volume scenarios evaluated.
Vehicle Miles Traveled (VMT)
The potential for the project to conflict or be inconsistent with CEQA Guidelines § 15064.3, subdivision (b) was evaluated based the project’s anticipated Vehicle Miles Traveled (VMT) performance metrics.
Applied Thresholds and Screening
The VMT characteristics of a development project are a primary factor in determining transportation impacts under CEQA. The Town of Yountville applies the VMT significance criteria and screening measures recommended in the technical memorandum VMT Recommendations for Town of Yountville, TJKM, 2021, which was developed in coordination with the Napa Valley Transportation Authority (NVTA). For residential development projects, a significant VMT impact may occur if the proposed project’s home-based VMT per capita exceeds 85 percent of the Yountville town average of 15.98 VMT per capita. This corresponds to a significance threshold of 13.58 VMT per capita. Applicable VMT performance metrics and averages are obtained from the Solano Napa Activity-Based Model (SNABM).
The project would also include up to 11,000 square feet of non-residential space that is expected to include a mix of food-oriented commercial space, local-serving service uses, and civic uses such as a town archive and/or art studios. Per the Town’s VMT recommendations memorandum, these types of uses would qualify as local-serving retail and be screened from further VMT analysis. The local-serving retail uses included in the project have a total Ms. Amber Sharpe Page 5 November 24, 2025
floor area of less than 50,000 square feet so may be presumed to have a less-than-significant impact on VMT since they by nature serve the surrounding area and tend to either shift or reduce, rather than generate new, VMT.
Residential VMT Assessment
The Yountville Commons project site is located within traffic analysis zone (TAZ) 159 of the SNABM model, which has an unadjusted baseline VMT per capita of 15.99 miles. This value forms the basis upon which project-specific adjustments to VMT are made. The VMT associated with a residential development is influenced by its density as well as affordability. The project’s VMT per capita was adjusted to account for residential density using a methodology contained in the publication Handbook for Analyzing Greenhouse Gas Emission Reductions, Assessing Climate Vulnerabilities, and Advancing Health and Equity, California Air Pollution Control Officers Association (CAPCOA), 2021. This methodology was developed in consideration of research that has shown per capita VMT to reduce as residential density is increased. For the purposes of this methodology, density was calculated by dividing the proposed 150 units by the 7.7-acre residential portion of the project site. The resulting 19.5 units per acre density is calculated to correspond to a 25.1 percent reduction in baseline per capita VMT according to the CAPCOA methodology, as shown on the enclosed spreadsheet.
The VMT generated per person at a residential development is also influenced by its affordability. The proposed project is intended to provide affordable housing with an emphasis on the local workforce, both of which are factors that reduce automobile reliance and the amount of VMT generated by residents. A methodology published in the 2021 CAPCOA publication cited above is typically used to determine the VMT reductions associated with provision of on-site affordable housing and would result in an additional VMT reduction of approximately 28 percent if applied to the entire project. Because the CAPCOA methodology specifically refers to deed-restricted attached multifamily units, with no adjustments or provisions available for “affordable by design” development types or orientation to the local workforce, affordability-based VMT reductions have not been applied in this analysis.
Accounting only for the effects of residential density, the baseline residential VMT per capita for the project is reduced from 15.99 VMT per capita to 11.98 VMT per capita. This is below the applied VMT significance threshold of 13.58 VMT/capita. Accordingly, the project as proposed would result in a less-than-significant VMT impact. The VMT findings are summarized in Table 7.
Table 7 – Vehicle Miles Traveled Analysis Summary
VMT Metric Town of
Yountville
Average
Significance
Threshold
(15% Below
Town Avg)
Project VMT Rate
Base
Unadjusted
(TAZ 159)
With
Adjustments
Significance
Finding
Residential VMT per Capita 15.98 13.58 15.99 11.98 Less than Significant
Notes: VMT performance metrics obtained from SNABM; VMT Rate is measured in VMT per Capita, or the number of daily miles driven per resident; TAZ = Transportation Analysis Zone In addition to considering the above quantitative model outputs, it is noted that the project’s proximity to central Yountville and the ability for residents to easily walk and bicycle to nearby destinations provides further support for the premise that the project would have a less-than-significant VMT impact. Stops for the Up Valley Connector bus service operated by NVTA are located within one-quarter mile walking distance of the site, providing transit service to locations throughout the Napa Valley between Calistoga and Napa Valley College.
Finding – The proposed project would have a less-than-significant impact on VMT.
Ms. Amber Sharpe Page 6 November 24, 2025
Conclusions and Recommendations
The proposed project is expected to generate an average of 1,079 trips per day, including 88 during the morning peak hour and 111 during the evening peak hour. The three study intersections are currently operating acceptably at LOS A and are expected to continue doing so under future volumes and with project traffic added. The proposed project would have a less-than-significant impact on VMT.
We hope this information is useful to Town staff in evaluating the proposed project. Thank you for giving us the opportunity to provide these services.
Sincerely,
Dalene J. Whitlock, PE (Civil, Traffic), PTOE
Senior Principal
DJW/djw/YOU021.L1
Enclosure: Internal Capture Spreadsheet, VMT Spreadsheet, LOS Calculations Project Name: Organization:
Project Location: Performed By:
Scenario Description: Date:
Analysis Year: Checked By:
Analysis Period: Date:
ITE LUCs1 Quantity Units Total Entering Exiting
Office 0
Retail 822 11 ksf 69 35 34
Restaurant 0
Cinema/Entertainment 0
Residential 220 150 du 68 40 28
Hotel 0
All Other Land Uses2 0
137 75 62
Veh. Occ.4 % Transit % Non-Motorized Veh. Occ.4 % Transit % Non-Motorized Office
Retail 1.00 0% 0% 1.00 0% 0%
Restaurant
Cinema/Entertainment
Residential 1.00 0% 0% 1.00 0% 0%
Hotel
All Other Land Uses2
Office Retail Restaurant Residential Hotel
Office
Retail
Restaurant
Cinema/Entertainment
Residential
Hotel
Office Retail Restaurant Residential Hotel
Office 0 0 0 0
Retail 0 0 9 0
Restaurant 0 0 0 0
Cinema/Entertainment 0 0 0 0 0
Residential 0 4 0 0
Hotel 0 0 0 0
Total Entering Exiting Land Use Entering Trips Exiting Trips All Person-Trips 137 75 62 Office N/A N/A
Internal Capture Percentage 19% 17% 21% Retail 11% 26%
Restaurant N/A N/A
External Vehicle-Trips5 111 62 49 Cinema/Entertainment N/A N/A External Transit-Trips6 0 0 0 Residential 23% 14%
External Non-Motorized Trips6 0 0 0 Hotel N/A N/A
1Land Use Codes (LUCs) from Trip Generation Manual , published by the Institute of Transportation Engineers. 2Total estimate for all other land uses at mixed-use development site is not subject to internal trip capture computations in this estimator. 3Enter trips assuming no transit or non-motorized trips (as assumed in ITE Trip Generation Manual ). 5Vehicle-trips computed using the mode split and vehicle occupancy values provided in Table 2-P.
Table 5-P: Computations Summary Table 6-P: Internal Trip Capture Percentages by Land Use 4Enter vehicle occupancy assumed in Table 1-P vehicle trips. If vehicle occupancy changes for proposed mixed-use project, manual adjustments must be 6Person-Trips
0 0
0 0
Table 4-P: Internal Person-Trip Origin-Destination Matrix* Origin (From) Destination (To)
Cinema/Entertainment
0 Table 3-P: Average Land Use Interchange Distances (Feet Walking Distance) Origin (From) Destination (To)
Cinema/Entertainment
NCHRP 684 Internal Trip Capture Estimation Tool
Yountville Commons
DJW
*Indicates computation that has been rounded to the nearest whole number.
Estimation Tool Developed by the Texas A&M Transportation Institute - Version 2013.1 PM Peak Hour
PM Street Peak Hour
Table 1-P: Base Vehicle-Trip Generation Estimates (Single-Use Site Estimate) Land Use Development Data (For Information Only ) Estimated Vehicle-Trips3 Table 2-P: Mode Split and Vehicle Occupancy Estimates
Land Use
Entering Trips Exiting Trips
Yountville Commons VMT Assessment
W-Trans 10/13/2025
Residential VMT Threshold
15.98 VMT/Capita Townwide Average - Town of Yountville
13.58 Town of Yountville Threshold = 15% below Town Average Unadjusted and Adjusted VMT
15.99 VMT/Capita TAZ 159
13.58 Threshold of Significance
-15.1% Project VMT Reduction Required to meet Threshold NO Is project below threshold?
A. Density Adjustment Source: CAPCOA 2021
150 Project Units
-25.10% VMT Reduction 7.70 Project Acres
-4.01 Adjustment to Base Project VMT/Capita 19.5 Project Density VMT Projections After Adjustments
15.99 TAZ VMT/Capita from SNABM
-4.01 Adjustment to Base Project VMT/Capita
11.98 Adjusted Project VMT/Capita
13.58 Town of Yountville Residential Threshold
YES Is project below threshold?