490 Mendocino Avenue, Suite 201 SANTA ROSA, CA 95401 707.542.9500 w-trans.com
March 15, 2023
Terry MacRae
Bon Voyage Management, a Texas LLC
2102 Cedar Springs Road
Dallas, TX 75201
VMT Assessment for the 1980 Yountville Cross Road Residential Development
Dear Mr. MacRae;
As requested, W-Trans has prepared a focused assessment of Vehicle Miles Traveled (VMT) for the residential development proposed for 1980 Yountville Cross Road in the Town of Yountville. Upon completion, the proposed project would include eightsingle family homes with eight accessory dwelling units (ADUs), as well as one duplex containing two low-income household units. The site is currently occupied by one single family home with an accessory unit. The net increase in development producing new vehicular trips and VMT would therefore be seven single-family units, one duplex unit (counted as two attached residential units), and seven ADUs.
The VMT associated with a project is the basis for determining traffic impacts under the California Environmental Quality Act (CEQA). Because the Town of Yountville has not yet adopted a standard of significance for evaluating VMT, guidance provided by the California Governor’s Office of Planning and Research (OPR) in the publication Transportation Impacts (SB 743) CEQA Guidelines Update and Technical Advisory, 2018, was used. This document indicates that a residential project generating vehicle travel that is 15 or more percent below the existing citywide or regional residential VMT per capita may indicate a less-than-significant transportation impact.
The OPR Technical Advisory also contains several criteria that may be used by jurisdictions to identify certain types of projects that are unlikely to have a VMT impact and can be “screened” from further VMT analysis. One of these screening criteria pertains to small projects, which OPR identifies as generating fewer than 110 vehicle trips per day. Given that the proposed project is in an infill location and contains a relatively small number of units, the ability for it to qualify for the “small project” VMT screening criteria was assessed.
The anticipated trip generation for the proposed project was estimated using standard rates published by the Institute of Transportation Engineers (ITE) in Trip Generation Manual, 11th Edition, 2021. Rates for “Single Family Detached Housing” (ITE LU#210) were applied for the existing and proposed single-family homes, and rates for “Single Family Attached Housing” (ITE LU#215) were applied for the two units contained in the duplex. The Trip Generation Manual does not contain rates for ADUs; since the units would be attached to the main residences and function similarly to an apartment, rates for the “Multifamily Housing (Low Rise) Not Close to Rail Transit (ITE LU#220) land use were applied. Because the proposed accessory units would be considered “Junior” ADUs of 500 square feet or less, the number of residents per unit would be less than a typical apartment. Based on census data obtained from the 2021 American Housing Survey, residential units of less than 500 square feet on average house
1.28 persons per unit, while residences ranging from 500 to 749 square feet have an average of 1.34 persons per unit. For the purposes of this analysis, ADU trip generation was assessed using person-based ITE rates, conservatively assuming an average occupancy of 1.5 persons per ADU. The proposed addition of eight ADUs is therefore estimated to house 12 residents. The existing ADU on the site, which would be demolished, was conservatively assumed to house one resident.
The expected trip generation potential for the proposed project is indicated in Table 1. Applying conservative assumptions, the project is expected to generate a net increase of 100 daily trips, which falls below the OPR “small project” screening criteria. As a result, it is reasonable to conclude that the project can be presumed to have a lessthan-significant impact on VMT.
Mr. Terry MacRae Page 2 March 15, 2023
Table 1 – Trip Generation Summary
Land Use ITE
Land Use #
Net Added
Development
Daily Trip Generation
Rate Trips
Proposed Project
Single Family Detached Housing 210 8 dwelling units 9.43 75 Single Family Attached Housing 215 2 dwelling units 7.20 14 Accessory Dwelling Unit 220 12 residents (8 units at 1.5 persons/unit)
1.86 22
Existing Development on Site
Single Family Detached Housing 210 1 dwelling unit 9.43 -9 Accessory Dwelling Unit 220 1 resident 1.86 -2
Net Increase in Daily Trips 100
Notes: Duplex contains two separate household units. New ADUs conservatively estimated to be occupied by 1.5 residents per unit on average, with a single resident conservatively assumed in the existing ADU.
Thank you for giving W-Trans the opportunity to provide these services. Please call if you have any questions.
Sincerely,
Zachary Matley, AICP
Principal
JZM/YOU020.L1-5