Transportation Impact Study — Cotati City Council, August 26, 2025

Balancing Functionality and Livability since 1995
w-trans.com

TRAFFIC ENGINEERING

TRANSPORTATION PLANNING
April 3, 2025
Prepared for the City of Cotati
Submitted by
W-Trans
Transportation Impact Study for the
120 East Cotati Avenue Residential Project

i Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Table of Contents
Executive Summary .................................................................................................................................................................. 1 Introduction................................................................................................................................................................................. 2 Transportation Setting............................................................................................................................................................. 8 Project Data ..............................................................................................................................................................................13 Circulation System ................................................................................................................................................................. 15 Vehicle Miles Traveled (VMT).............................................................................................................................................. 18 Safety Issues..............................................................................................................................................................................19 Emergency Access.................................................................................................................................................................. 22 Capacity Analysis.................................................................................................................................................................... 23 Parking........................................................................................................................................................................................30 Conclusions and Recommendations............................................................................................................................... 32 Study Participants and References................................................................................................................................... 34 Figures

1. Study Area and Existing Lane Configurations.................................................................................................................. 7

2. Site Plan.......................................................................................................................................................................................14

3. Existing and Future Traffic Volumes..................................................................................................................................25

4. Project Traffic Volumes...........................................................................................................................................................27 Tables

1. Bicycle Facility Summary .......................................................................................................................................................10

2. Transit Routes............................................................................................................................................................................11

3. Collision Rates for the Study Intersections......................................................................................................................12

4. Trip Generation Summary.....................................................................................................................................................13

5. Trip Distribution Assumptions.............................................................................................................................................13

6. Maximum Queues in Dedicated Left-Turn Lanes..........................................................................................................21

7. Intersection Level of Service Criteria ................................................................................................................................. 23

8. Existing Peak Hour Intersection Levels of Service.........................................................................................................24

9. Future Peak Hour Intersection Levels of Service ...........................................................................................................26

10. Existing and Existing plus Project Peak Hour Intersection Levels of Service .......................................................28

11. Future and Future plus Project Peak Hour Intersection Levels of Service ............................................................28

12. Parking Analysis Summary....................................................................................................................................................30 ii Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Plates

1. Existing Cross-Section Midblock on East Cotati Avenue.............................................................................................16

2. Existing Cross-Section on East Cotati Avenue at the Median Island.......................................................................16

3. Proposed Cross-Section Mid-Block on East Cotati Avenue........................................................................................17

4. Proposed Cross-Section on East Cotati Avenue at the Median Island ...................................................................17 Appendices
A. Collision Rate Calculations
B. Queueing Calculations
C. Intersection Level of Service Calculations
1 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Executive Summary
The proposed mixed-use development would be located at 120 East Cotati Avenue in the City of Cotati; the project site is currently vacant. The project would result in the construction of a three-story apartment complex with ground-floor retail and a parking garage. In addition, a new sidewalk would be installed on Charles Street and the existing sidewalk on East Cotati Avenue would be expanded to ten feet along project frontage. The project would be expected to generate an average of 277 daily trips, with 19 occurring during the a.m. peak hour and 16 during the p.m. peak hour.

A review of the collision history indicates that one of the three study intersections had a collision rate above the statewide average for similar facilities. The intersection of East Cotati Avenue/Charles Street, which had an aboveaverage collision rate, had a pattern of rear-ends involving vehicles stopped at the intersection. However, no remedial action is recommended asthis type of incident is due to driver violations so cannot be addressed through any physical changes to the intersection. There were no collisions involving either pedestrians or bicyclists at any of the study intersections during the five-year study period.

Existing pedestrian, bicycle, and transit facilities along project frontage and in the vicinity of the project site would provide adequate access. The project would improve pedestrian access by widening the existing sidewalk on East Cotati Avenue and constructing a new sidewalk on Charles Street. Widening the sidewalk on East Cotati Avenue would reduce roadway width, requiring restriping of East Cotati Avenue to provide the additional width needed for the sidewalk. With lane restriping, the project would not conflict with any policies for these transportation modes and therefore have a less-than-significant impact.

The project would screen out as having the presumption of a less-than-significant impact on VMT.

Potential access schemes were analyzed based on several safety criteria. Sight distances at the proposed project driveway locations would meet or exceed recommended minimums. The lane merge on East Cotati Avenue for eastbound traffic would not present an issue as drivers would be fully in a single lane prior to reaching the driveway location and would therefore have sufficient time to react to vehicles entering or exiting the project driveway on East Cotati Avenue. Volumes on Charles Street may exceed expectations for a local road, likely due to the street being used as bypass for the intersection of East Cotati Avenue/Old Redwood Highway. Though project volumes may contribute to increased traffic, traffic from the proposed project should be accommodated as the site’s frontage on Charles Street could reasonably be anticipated to generate trips on this street.

The project would not cause any intersection to queue beyond storage lane capacity so would have a less-thansignificant impact as regards safety and would also have a less-than-significant impact on emergency response.

An analysis of operation of the study intersections indicates that all study intersections are operating acceptably.

Operation at the northbound Charles Street approach is projected to deteriorate to an acceptable LOS F under future volumes. Upon the addition of project-generated volumes, no intersection would deteriorate to an unacceptable level. The northbound Charles Street approach would operate at an LOS F with or without project volumes. The project would therefore not have an adverse effect on operation based on City policy.

The proposed parking supply of 54 on-site parking spaces is adequate given the parking reductions due to the State Density Bonus Law and the inclusion of supportive units. It is recommended that parking spaces not be assigned to individual units to allow maximum flexibility in use of the parking supply by both the residential and retail components.
2 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Introduction
This report presents an analysis of the potential traffic impacts and adverse operational effects that would be associated with development of a proposed mixed-use project to be located at 120 East Cotati Avenue in the City of Cotati. The traffic study was completed in accordance with the criteria established by the City of Cotati and is consistent with standard traffic engineering techniques.

Prelude
The purpose of a traffic impact study is to provide City staff and policy makers with data that they can use to make an informed decision regarding the potential transportation impacts of a proposed project, and any associated improvements that would be required to mitigate these impacts to an acceptable level under CEQA, the City’s General Plan, or other policies. This report provides an analysis of those items that are identified as areas of environmental concern under the California Environmental Quality Act (CEQA) and that, if significant, require an EIR. It is noted that the proposed project is exempt from CEQA analysis as it is being processed through a streamlined ministerial approval procedure under the provisions of Assembly Bill 2162. However, CEQA items were analyzed for information purposes. Potential impacts associated with access for pedestrians, bicyclists, and to transit; the vehicle miles traveled (VMT) generated by the project; potential safety concerns such as increased queuing in dedicated turn lanes, adequacy of sight distance, need for turn lanes, and need for additional right-ofway controls; and emergency access are addressed in the context of the CEQA criteria. While no longer a part of the CEQA review process, vehicular traffic service levels at key intersections were evaluated for consistency with General Plan policies by determining the number of new trips that the proposed use would be expected to generate, distributing these trips to the surrounding street system based on anticipated travel patterns specific to the proposed project, then analyzing the effect the new traffic would be expected to have on the study intersections and need for improvements to maintain acceptable operation. Adequacy of parking is also addressed as a policy issue.

Applied Standards and Criteria
The report is organized to provide background data that supports the various aspects of the analysis, followed by the assessment of CEQA issues and then evaluation of policy-related issues. The CEQA criteria evaluated are as follows.

Would the project:
a. Conflict with a program, plan, ordinance, or policy addressing the circulation system, including transit, roadway, bicycle, and pedestrian facilities?
b. Conflict or be inconsistent with CEQA Guidelines § 15064.3, subdivision (b)? c. Substantially increase hazards due to a geometric design feature (e.g., sharp curves or dangerous intersections) or incompatible uses (e.g., farm equipment)? d. Result in inadequate emergency access?
The project was also evaluated against the City’s policies, which provide guidance relative to traffic impacts for CEQA issues as well as the effects caused by traffic associated with new development. Based on the most recent criteria published by the City, the project would have a significant impact or an adverse effect on traffic operation if it results in any of the following conditions.
3 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Cotati General Plan
GOAL CI 1
Create a Circulation Network That Reinforces the Desired Land Use Pattern for Cotati, and Provides for the Safe and Efficient Movement of People and Goods to All Parts of the City Objective CI 1A
Maintain Safe and Efficient Operating Conditions on the Citywide Circulation Network Policy CI 1.2
Ensure that the City’s circulation network is a well-connected system of streets, roads, highways, sidewalks, and bicycle/pedestrian paths that effectively accommodates vehicular and non-vehicular traffic in a manner that considers the context of surrounding land uses and the needs of all roadway users.

Policy CI 1.3
Establish a minimum motor vehicle Level of Service (LOS) standard of LOS D at intersections. The following shall be taken into consideration in applying LOS standards:
• Levels of service shall be calculated using the average hourly delay for all vehicles entering the intersection, and assessed for the entire peak hour (60 minutes) rather than the peak 15- minute period (PHF=1.0). • At unsignalized intersections, levels of service shall be determined for both controlled movements and for the overall intersection. Controlled movements operating at LOS E or LOS F are allowable if 1) the intersection is projected to operate at LOS C or better overall, and 2) the projected traffic volume on the controlled movement is 30 vehicles or less per hour on approaches with single lanes, or on multi-lane approaches, 30 vehicles or less per hour on lanes serving left turns and through movements. • Level of service standards shall not apply to minor intersections comprised of only local streets. • For projects within the City limits that are consistent with the General Plan, a standard of LOS E is considered to be acceptable for intersections within the boundaries of the Downtown Cotati Specific Plan. • Intersection queuing shall be evaluated in tandem with LOS. Projected 95th percentile queues at signalized intersections shall not extend through upstream signalized intersections.

Policy CI 1.6
When analyzing impacts to the circulation network created by new development or roadway improvements, consider the needs of all users including those with disabilities, ensuring that pedestrians, bicyclists, and transit riders are considered at an equal level to the needs of automobile drivers.

Policy CI 1.11
Retain the viewpoint of pedestrians and bicyclists as the primary perspective when identifying Hub-related traffic improvements.

Policy CI 1.12
Enhance the safety of pedestrian crossings in the Hub area while ensuring a delightful downtown experience.

Policy CI 1.17
Consider alternatives to traffic signals where appropriate conditions exist to maximize intersection efficiency, maintain traffic flow, reduce accident severity, and enhance pedestrian and bicyclist circulation.

Policy CI 1.18
Intersections shall be designed to provide adequate and safe access for all users including pedestrians, bicyclists, and motorists of all ages and abilities.
4 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Action CI 1l: Monitor residential streets as needed to ensure that traffic volumes do not exceed a maximum of 1,500 to 2,000 vehicles per day on improved streets (those with curb, gutter, sidewalk, and well-conditioned pavement), and a maximum of 1,000 to 1,500 vehicles per day on streets which are more rural in nature (typified by poorly-conditioned pavement and the absence of pedestrian walkways). If traffic volumes exceed these criteria, the City shall consider implementing traffic calming measures to reduce through traffic volumes.

Action CI 1m: Require developers to design local roadways (i.e., streets other than arterials and collectors) for speeds of 25 miles per hour or less.

Action CI 1n: Review plans for new or modified intersections to ensure that lane configurations are limited where possible to provide for moderate speeds and pedestrian and cyclist safety, and that curb extensions are installed where appropriate to reduce driving speeds and shorten pedestrian crossing distances.

Objective CI 1C
Ensure that New Development Contributes to the City’s Desired Circulation Network Policy CI 1.19
Require new development to include effective linkages to the surrounding circulation system for all modes of travel, to the extent feasible.

Policy CI 1.20
Require new development to contribute its proportional share cost of circulation improvements necessary to address cumulative transportation impacts on roadways throughout the City as well as the bicycle and pedestrian network.

Policy CI 1.21
Require development projects to provide land dedications or pay fees in order to provide bike paths, sidewalks, and walkways.

Action CI 1o: Prepare an Impact Fee Study to support an updated development impact fee that requires new development to pay its proportional share of circulation improvements, including but not limited to the improvements shown on Figure 2.1, identified as actions in this section, and/or identified in the General Plan Environmental Impact Report or the Traffic Impact Fee Study, as well as pedestrian and bicycle facilities such as those included in the Bicycle and Pedestrian Master Plan and those described in this Circulation Element.

Action CI 1r: As part of the development review process, require new development to mitigate circulation impacts by making improvements to the motorized and non-motorized circulation networks as necessary, and in a fair manner with an established nexus between the level of impact and required improvements and/or contributions.

Action CI 1s: As part of the development review process, ensure that new development facilitates walking, biking, and transit modes; incorporates streets that are designed to maintain safe and efficient traffic flow; constructs or (if deemed appropriate by the City Engineer) contributes funds toward construction of off-site improvements necessary to mitigate traffic impacts; provides adequate emergency vehicle access; and pays development impact fees that contribute to cumulative circulation improvements.

GOAL CI 2
Maintain and Expand a Safe and Efficient Pedestrian, Bicycle, and Transit Network That Connects Neighborhoods With Key Destinations to Encourage Travel by Non-Automobile Modes While Also Improving Public Health Objective CI 2A
Maintain and Develop a Network of Sidewalks and Pathways to Provide for Safe and Convenient Pedestrian Travel 5 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Policy CI 2.1
Establish and maintain a system of pedestrian facilities and crossing enhancements that are consistent with the City’s Bicycle and Pedestrian Master Plan.

Policy CI 2.2
Support establishment of special assessments of affected property owners in order to provide funding to install walkways and fill gaps in the existing pedestrian network.

Policy CI 2.3
Require development projects to construct sidewalks and walkways on and off-site in order to maintain consistency with the City’s Bicycle and Pedestrian Master Plan, and as dictated by the location of transit stops and common pedestrian destinations.

Policy CI 2.6
Create an accessible circulation network that is consistent with guidelines established by the Americans with Disabilities Act (ADA), allowing mobility-impaired users such as the disabled and elderly to safely and effectively travel within and beyond the City.

Policy CI 2.10
Continue to provide secure bicycle racks in the Hub, future and existing commercial areas, park-and-ride transit facilities, schools, and multiple unit residential developments.

Action CI 2a: As part of the development process, review development applications to ensure compliance with the City’s Bicycle and Pedestrian Master Plan.

Objective CI 2B
Provide a Citywide Network of Bicycle Routes, Multi-Use Paths, and Facilities to Accommodate Travel by Bicycle Policy CI 2.11
Establish and maintain bicycle facilities that are consistent with the network depicted in the City’s Bicycle and Pedestrian Master Plan.

Policy CI 2.13
Bicycle parking facilities such as bike racks, bike lockers, and secure bike corrals shall be provided at locations where there is a concentration of residents, visitors, students, or employees.

GOAL CI 3
Reduce Vehicle Miles Traveled (VMT) in Order to Reduce Congestion and Help Achieve Regional Efforts to Reduce Greenhouse Gas (GHG) Emissions
Objective CI 3A
Reduce the Levels of Greenhouse Gas Emissions Created by Automobile Traffic in Cotati GOAL CI 4
Maintain Efficiency of the Circulation Network through Coordination With Regional Planning Efforts Objective CI 5B
Maintain Parking Requirements and Practices that Complement the Desired Land Use Pattern while Minimizing Neighborhood Impacts
6 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Policy CI 5.4
Ensure that the parking demand associated with future development does not adversely impact adjacent residential areas due to spillover parking demand.

Project Profile
The project as proposed includes 43 below-market-rate dwelling units, a manager’s unit, and 4,000 square feet of retail space. The project site is located at 120 East Cotati Avenue, as shown in Figure 1.

KEEP KEEP
CLEAR
1 2 3
8 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Transportation Setting
Study Area and Periods
The study area varies depending on the topic. For pedestrian trips it consists of all streets within a half mile of the project site that would lie along primary routes of pedestrian travel, or those leading to nearby generators or attractors. For bicycle trips it consists of all streets within one mile of the project site that would lie along primary routes of bicycle travel. For the safety and operational analyses, it consists of the project frontage and the following intersections:

1. East Cotati Avenue/Old Redwood Highway

2. East Cotati Avenue/La Plaza

3. East Cotati Avenue/Charles Street
Operating conditions during the a.m. and p.m. peak periods were evaluated to capture the highest potential impacts for the proposed project as well as the highest volumes on the local transportation network. The morning peak hour occurs between 7:00 and 9:00 a.m. and reflects conditions during the home to work or school commute, while the p.m. peak hour occurs between 4:00 and 6:00 p.m. and typically reflects the highest level of congestion during the homeward bound commute. Counts were obtained for the study intersections January 28, 2025.

Existing Transportation Facilities
Study Intersections
East Cotati Avenue/Old Redwood Highway is a four-legged, signalized intersection with protected left-turn phasing on all approaches except the westbound approach, where left turns are prohibited except by transit buses. There are marked pedestrian crosswalks on each leg.

East Cotati Avenue/La Plaza is an unsignalized four-legged intersection with stop controls on the northbound and southbound approaches, both of which are restricted to right turns only. Marked pedestrian crosswalks are provided on the south and north legs. The southern leg is one-way in the northbound direction.

East Cotati Avenue/Charles Street is a tee intersection, unsignalized, with a stop control on the northbound approach. Marked pedestrian crosswalks are provided on the west and south legs. The crosswalk on the west leg is supplemented with a pedestrian refuge median within the center two-way left-turn lane.

The locations of the study intersections and the existing lane configurations and controls are shown in Figure 1.

Study Roadways
East Cotati Avenue is designated as a major arterial by the City of Cotati. The 2.35-mile long corridor connects Old Redwood Highway at the Cotati “Hub” to Petaluma Hill Road, serving residential neighborhoods in Cotati and Rohnert Park, as well as the southern entrance to Sonoma State University.

La Plaza is a local road that bounds the hexagonal plaza in Downtown Cotati. The segment on the project frontage is one way in the northbound direction to East Cotati Avenue, with one 12-foot travel lane and angled parking on the west side of the roadway.

Charles Street is a local street, approximately 25 feet wide. 9 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Existing and Planned Pedestrian Facilities
Pedestrian facilities include sidewalks, crosswalks, pedestrian signal phases, curb ramps, curb extensions, and various streetscape amenities such as lighting, benches, etc. In general, a network of sidewalks, crosswalks, pedestrian signals, and curb ramps provide access for pedestrians in the vicinity of the proposed project site • East Cotati Avenue – Continuous sidewalk coverage is provided on East Cotati Avenue from Old Redwood Highway to Charles Street and beyond along all frontages of the project site. Marked pedestrian crosswalks are provided on each leg of East Cotati Avenue/Old Redwood Highway, on the south leg of East Cotati Avenue/La Plaza, and a midblock striped pedestrian crossing with a center refuge is provided on the west leg of East Cotati Avenue/Charles Street. Curb ramps are provided at each leg of the study intersections. • La Plaza – Continuous sidewalks are provided on both sides of La Plaza between East Cotati Avenue and Main Avenue.
• Charles Street – A continuous sidewalk is provided only on the east side of the street. The project frontage along Charles Street does not have any sidewalk. In general, Charles Street is a local street that provides access to residences and some commercial parking near Old Redwood Highway.

The City of Cotati Active Transportation Plan (ATP), Sonoma County Transportation Authority, 2024 describes planned future facilitiesin the City. In the project vicinity, the plan describes filling in existing sidewalk gaps on La Plaza and streets of the outer hexagon of the plaza, the Loop, including Charles Street.

Existing and Planned Bicycle Facilities
The Highway Design Manual, Caltrans, 2020, classifies bikeways into four categories:
• Class I Multi-Use Path – a completely separated right-of-way for the exclusive use of bicycles and pedestrians with cross flows of motorized traffic minimized.
• Class II Bike Lane – a striped and signed lane for one-way bike travel on a street or highway. • Class III Bike Route – signing only for shared use with motor vehicles within the same travel lane on a street or highway.
• Class IV Bikeway – also known as a separated bikeway, a Class IV Bikeway is for the exclusive use of bicycles and includes a separation between the bikeway and the motor vehicle traffic lane. The separation may include, but is not limited to, grade separation, flexible posts, inflexible physical barriers, or on-street parking.

In the project area, Class II bike lanes exist on East Cotati Avenue between Old Redwood Highway and Petaluma Hill Road. A Class II bike lane is also provided on Old Redwood Highway between Commerce Boulevard and the City of Petaluma, though a segment between East Cotati Avenue and McGinnis Circle is currently designated a Class III bike route. A Class I multi-use path is located approximately 500 feet east of the proposed project, known as the Laguna de Santa Rosa Trail. This trail extends for approximately 2.24 miles from Liman Avenue to Avram Avenue. There is a gap along the trail, south of East Cotati Avenue, that will be filled upon implementation of the Cotati Bicycle & Pedestrian Master Plan. Several roads in the area are designated as Class III Bike Boulevards which are proposed to be redesignated as Class IIIB bike boulevards and extended in multiple locations. Table 1 summarizes the existing and planned bicycle facilities in the project vicinity. 10 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Table 1 – Bicycle Facility Summary
Status
Location
Class Length
(miles)
Begin Point End Point
Existing
Laguna de Santa Rosa Trail1 I 1.34 E Cotati Ave Avram Ave Laguna de Santa Rosa Trail1 I 0.90 Marsh Wy Liman Wy
Myrtle Ave II 0.68 Old Redwood Hwy Lancaster Dr
Old Redwood Hwy II 0.50 Commerce Blvd E Cotati Ave
Old Redwood Hwy2 II 3.75 Petaluma City Limit McGinnis Cir W Sierra Ave/E Cotati Ave1 II 3.30 Cotati City Limit Petaluma Hill Rd Benson Ln III 0.17 Park Ave Loretto Ave
Charles St III 0.11 Old Redwood Hwy E Cotati Ave
La Plaza3 III 0.33 E Cotati Ave E Cotati Ave
Lasalle Ave III 0.38 Loretto Ave E Cotati Ave
Lincoln Wy1 III 0.41 Loretto Ave Lancaster Dr
Loretto Ave III 0.13 Benson Ln Lincoln Ave
Marsh Wy III 0.11 Laguna de Santa Rosa
Trail
E Cotati Ave
Old Redwood Hwy III 0.23 McGinnis Cir E Cotati Ave
Planned
Burton Ave/E Cotati Ave Trail I 0.10 E Cotati Ave Burton Ave Laguna de Santa Rosa Trail I 0.10 Lincoln Ave E Cotati Ave E School St II 0.27 SR-101 Undercrossing W Sierra Ave
Benson Ln IIIB 0.17 Park Ave Loretto Ave
Lasalle Ave IIIB 0.38 Loretto Ave E Cotati Ave
Lincoln Wy1 IIIB 0.68 Loretto Ave Cotati SMART Station
Loretto Ave IIIB 0.13 Benson Ln Lincoln Ave
Marsh Wy IIIB 0.11 Laguna de Santa Rosa
Trail
E Cotati Ave
Myrtle Ave IV 0.68 Old Redwood Hwy Lancaster Dr
W Sierra Ave IV 0.67 Cotati City Limit Old Redwood Hwy
Note: 1All or portions of these bikeways are located within the City of Rohnert Park; 2All or portions of these bikeways are located in unincorporated County of Sonoma; 3La Plaza is a loop road Source: City of Cotati Active Transportation Plan (ATP), Sonoma County Transportation Authority, 2024 Existing Transit Facilities
Sonoma County Transit (SCT), Golden Gate Transit, and Sonoma-Marin Area Rail Transit (SMART) are the transit providers in the City of Cotati. SCT Routes 10, 26, and 48 provide service to destinations throughout the City and surrounding communities. Golden Gate Transit provides intercity connections between the North Bay and San Francisco. Bus routes are served by stops on Old Redwood Highway between La Plaza and East Cotati Avenue 11 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
referred to as the “Cotati Hub.” Sonoma-Marin Area Rail transit (SMART) provides passenger rail service to communities in Sonoma and Marin County. Existing transit routes and their operation are summarized in Table 2.

Table 2 – Transit Routes
Transit
Agency
Route
Distance
to Stop
(mi)1
Service Connection
Days of
Operation
Time Frequency
Golden Gate Transit
Route 101 0.1 Daily 4:08 a.m. – 10:34 a.m. 60 min San Francisco Sonoma County Transit
Route 10 0.1 Mon-Fri
Sat-Sun
6:15 a.m. – 6:15 p.m.
7:55 a.m. – 5:15 p.m.
50 min
50 min
Cotati SMART Station, Rohnert Park,
Sonoma State University
Route 26 0.1 School Days 8:07 a.m. 1 EB bus Sonoma State University Route 48 0.1 Mon-Fri
Sat-Sun
6:29 a.m. – 10:52. p.m.
7:18 a.m. – 8:08 p.m.
8 buses
5 buses
Coddington/N Santa Rosa, Santa
Rosa Transit Mall, Rohnert Park,
Penngrove, Petaluma Transit Mall
Sonoma-Marin Area Rail Transit
Fixed 0.7 Mon-Fri
Sat-Sun
5:11 a.m. – 11:49 p.m.
7:38 a.m. – 8:40 p.m.
30-60 min
2 hours
Sonoma County Airport to Larkspur
Ferry Terminal Building
Note: 1 Defined as the shortest walking distance between the project site and the nearest bus stop Source: Goldengate.org; sctransit.com; sonomamarintrain.org Two to three bicycles can be carried on most SCT buses. Bike rack space is on a first come, first served basis.

Additional bicycles or foldable bicycles are allowed on SCT buses based on size and the discretion of the driver.

Golden Gate Transit only permits bicycles on the front-loading racks with capacity for two to three bicycles. SMART allow bicycles to be carried onboard, with each two-car train having capacity for up to 24 bicycles.

Dial-a-ride, also known as paratransit, or door-to-door service, is available for those who are unable to independently use the transit system due to a physical or mental disability within three-quarters of a mile from existing routes. SCT Paratransit is designed to serve the needs of individuals with disabilities within the City of Cotati and the County of Sonoma.

Collision History
The collision history for the study area was reviewed to determine any trends or patterns that may indicate a safety issue. Collision rates were calculated based on records available from the California Highway Patrol as published in their Statewide Integrated Traffic Records System (SWITRS) reports. The most current five-year period available is January 1, 2020, through December 31, 2024.

As presented in Table 3, the calculated collision rates for the study intersections were compared to average collision rates for similar facilities statewide, as indicated in 2022 Crash Data on California State Highways, California Department of Transportation (Caltrans). These average rates statewide are for intersections in the same environment (urban, suburban, or rural), with the same number of approaches (three or four), and the same controls (all-way stop, two-way stop, or traffic signal). The intersections of East Cotati Avenue/Old Redwood Highway and East Cotati Avenue/La Plaza both had collision rates below the statewide averages for similar facilities, indicating no concerning patterns. The intersection of East Cotati Avenue/Charles Street had a higher rate of both collisions and injuries compared to the statewide average for similar facilities. 12 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Table 3 – Collision Rates for the Study Intersections
Study Intersection Number of
Collisions
(2020-2025)
Calculated
Collision Rate
(c/mve)
Statewide Average
Collision Rate
(c/mve)

1. East Cotati Ave/Old Redwood Hwy 9 0.22 0.33

2. East Cotati Ave/La Plaza 3 0.11 0.20

3. East Cotati Ave/Charles St 6 0.19 0.13
Note: c/mve = collisions per million vehicles entering; bold indicates a rate that exceeds the Statewide average Because the collision rate for East Cotati Avenue/Charles Street exceeded the Statewide average, though nominally, the individual incidents were further reviewed. Four out of the six collisions were reported as drivers rear-ending a vehicle stopped at the intersection, and three of these were on the stop-controlled northbound approach. Of the rear-end collisions, two were attributed to driving at an unsafe speed, one to the driver following too closely, and the last to unsafe starting. The remaining collisions were reported as a hit-and-run (leaving the Primary Collision Factor unknown) where the driver ran off the road and hit an object, and a sideswipe collision due to unsafe merging. Although there was a pattern of similar collisions at this intersection, they were attributed to driver violations not influenced by the intersection itself. It is noted that the stop sign is clearly visible to approaching drivers. Six collisions during a five-year period does not constitute a pattern of underlying issues at this intersection so no remedial action is suggested.

The collision rate calculations are provided in Appendix A.

Pedestrian Safety
The five-year period was reviewed for the study area was reviewed to determine any trends or patterns that may indicate a safety issue for pedestrians. During the five-year study period there were no reported collisions involving pedestrians at the study intersections.

Bicyclist Safety
There were no reported collisions involving a bicyclist at any of the study intersections during the same five-year period, indicating no prevalent safety issues for bicyclists. 13 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Project Data
The project consists of a three-story mixed-use building with 44 dwelling units, a manager’s unit, and approximately 4,000 square feet of retail space on the ground floor. The dwelling unit supply would be composed of 11 studios, 10 one-bedroom, 12 two-bedroom, and 11 three-bedroom apartments. The site would be accessible via two driveways, one on East Cotati Avenue and another on Charles Street, leading into the parking garage. The proposed project site plan is shown in Figure 2.

Trip Generation
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 for “Low-Rise Residential with Ground Floor Commercial GFA (1-25k)” (ITE LU #230). Based on application of these assumptions, the proposed project is expected to generate an average of 277 trips per day, including 19 a.m. peak hour trips and 16 trips during the p.m. peak hour. The expected trip generation potential for the proposed project is indicated in Table 4.

Table 4 – Trip Generation Summary
Land Use Units Daily AM Peak Hour PM Peak Hour
Rate Trips Rate Trips In Out Rate Trips In Out
Proposed
Apartments w/Ground
Floor Commercial
44 du 6.30 277 0.44 19 4 15 0.36 16 11 5
Note: du = dwelling unit
Trip Distribution
The pattern used to allocate new project trips to the street network was determined by reviewing existing turning movements at the study intersections as well as regional knowledge of the study area. The applied distribution assumptions and resulting trips are shown in Table 5.

Table 5 – Trip Distribution Assumptions
Route Percent Daily Trips AM Trips PM Trips
To/from north via Old Redwood Hwy 30% 83 6 5
To/from south via Old Redwood Hwy 25% 69 4 4
To/from east via E Cotati Ave 30% 83 6 5
To/from west via E Cotati Ave 15% 42 3 2
TOTAL 100% 277 19 16
Transportation Impact Study for the 120 East Cotati Avenue Residential Project cot092-4.ai 2/25
Figure 2 – Site PlanSource: HKIT Architects 2/11
=
:+2
9 9
9

352-(&7'$7$
)/225 %5 $5($
6)
68%727$/
3$5.,1*
727$/
%5

%5

678',2

6)
6)
727$/81,76
727$/%8,/',1*$5($
6)

3523(57</,1(
/2%%<
3$5.,1*

63$&(6

9 (9
9$1
0$,/
%,.(50
6)
75$6+
6)
5
6(59
6)
75$6+
6)
(/(&
6)
0$,17
6)
5(7$,/
6)
3523
0*07
6)
(/(9

(;,67,1* 6,'(:$/.
/$3/$=$67
&+$5/(667
&27$7, $9(

(9(9(9(9(9(9(9
(9(9(9(9(9(9

5

SDUNLQJVSDFHV
0(&+6) 5(7$,/ 6)
7 )3803
':
*$5$*(
&
VSDFHV
&23<5,*+7
+.,7$5&+,7(&76
6FDOH
-RE1R
'DWH
%\
5HIHUHQFH

1,17+675((768,7(2$./$1'&$
7
)
:::+.,7&20
6
/(9(/ &27$7,&200216

(&27$7,$9(&27$7,&$

$/5
758(
1257+

/(9(/
.(<127(6
(;,67,1*%866723(;,67,1*%8,/',1*9(+,&8/$5(175$1&(%,.(/$1(23(163$&(:$7(575($70(17$5($ 15 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Circulation System
This section addresses the first transportation bullet point on the CEQA checklist, which relates to the potential for a project to conflict with a program, plan, ordinance, or policy addressing the circulation system, including transit, roadway, bicycle, and pedestrian facilities.

Pedestrian Facilities
Project Impacts on Pedestrian Facilities
Given the proximity of the Downtown Cotati area and Sonoma State University to the site, it is reasonable to assume that some project patrons and employees will want to walk, bicycle, and/or use transit from the project site. Sidewalks exist along the project frontage. A sidewalk exists along the western and northern project frontages. There is no sidewalk on Charles Street along the project frontage. No other pedestrian paths currently exist. The project would include installation of a sidewalk on Charles Street where there currently is none and a new 10-foot-wide sidewalk along East Cotati Avenue. This would include a driveway ramp and the elimination of two to three parking spaces at each of the proposed project driveway locations. The project would improve pedestrian facilities by adding a sidewalk where none currently exists as well as expanding the width of the sidewalk on East Cotati Avenue.

Finding – The project would not conflict with any policies related to pedestrian facilities.

Bicycle Facilities
Project Impacts on Bicycle Facilities
Existing bicycle facilities, including the Class II bicycle lane on the project frontage, together with shared use of minor streets provide adequate access for bicyclists. The site plan indicates the project would not affect existing or planned bicycle facilities.

Bicycle Storage
The project site plan does not identify the provision for short-term bicycle parking. Long-term bicycle parking would be provided by a bike room on the ground floor with capacity for 104 bicycles. The City of Cotati Municipal Code requires multifamily uses to include one bicycle parking space for every four units with at least 75 percent of the total spaces meant for long-term parking if the building includes more than 14 total units, or 11 spaces for the 44 units. The proposed supply of 104 spaces therefore exceeds City Code requirements.

Finding – The project would not conflict with applicable policies regarding bicycle facilities.

Transit Facilities
Impact on Transit Facilities
Multiple bus stops exist near the project site within acceptable walking distance, including a stop on the east side of La Plaza. Based on estimates from the City of Cotati Active Transportation Plan, 2024, four percent of City residents use public transportation. As such, current facilities are expected to be adequate to accommodate project-generated transit trips.
16 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Finding – The project would be consistent with policies related to transit facilities.

Roadway Facilities
Impact on Roadway Facilities
The project identifies widening the sidewalk on East Cotati Avenue to ten feet wide. Currently, East Cotati Avenue has an approximate width of 71.5 feet curb to curb according to City striping and pavement marking plans. The cross sections of the existing configuration of East Cotati Avenue at the midblock and near the intersection with Charles Street are presented in Plate 1 and Plate 2.

Plate 1 Existing Cross-Section Midblock on East Cotati Avenue Plate 2 Existing Cross-Section on East Cotati Avenue at the Median Island To accommodate an additional five feet of sidewalk on East Cotati Avenue, the following changes to the existing striping are recommended,

1. Reduce the bicycle lane width to five feet;

2. Reduce the parking lane width to seven feet; and

3. Restripe the eastbound travel lane and reduce width from 12.5 to 11 feet. 17 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
The cross sections for the proposed reconfiguration of East Cotati Avenue at the midblock and near the intersection with Charles Street are presented in Plate 3 and Plate 4.

Plate 3 Proposed Cross-Section Mid-Block on East Cotati Avenue Plate 4 Proposed Cross-Section on East Cotati Avenue at the Median Island The sidewalks would otherwise not impact roadway facilities if built to City Standards including features such as drainage and curb dimensions.

Finding – The widening of sidewalk by the project would require restriping on East Cotati Avenue.

Recommendation – Restripe the lanes East Cotati Avenue between the two-way left-turn lane/refuge island and project frontage to accommodate a wider sidewalk along the project frontage.

Significance Finding – The proposed project would not conflict with any plans or policies for transportation facilities and would improve pedestrian access near the project site. 18 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
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). Senate Bill (SB) 743 established the change in Vehicle Miles Traveled (VMT) as a result of a project as the basis for determining California Environmental Quality Act (CEQA) impacts with respect to transportation and traffic.

The project-related VMT was assessed by applying the City of Cotati’s Guidelines for Analysis of Vehicle Miles Traveled (VMT), adopted in 2020. The California Governor’s Office of Planning and Research (OPR) publication Transportation Impacts (SB 743) CEQA Guidelines Update and Technical Advisory, 2018, was also referenced. Per the City’s policy, VMT for mixed use projects was assessed by applying the significance threshold for each use.

Residential VMT
For residential projects, VMT is assessed using vehicle miles traveled per capita as estimated in the Sonoma County Transportation Authority (SCTA) travel demand model. VMT per capita measures home-based trips, or trips that have the place of residence as one of the trip ends. Based on data from the February 2022 update of the SCTA model, the City of Cotati has a baseline average residential VMT of 18.3 miles per capita. Applying the City guidelines, a residential project generating a VMT that is 15 percent or more below this value, or 15.5 miles per capita or less, would have a less-than-significant VMT impact. The SCTA model includes traffic analysis zones (TAZ) covering geographic areas throughout Sonoma County, and the Cotati Village project site is located within TAZ 433, which has a baseline VMT per capita of 14.9 miles. The residential component would therefore screen out as being presumed to have a less-than-significant impact on VMT.

Retail VMT
The City VMT guidelines state that a retail project is considered to have a significant VMT impact if it would result in a net increase in regional total VMT. The policy notes that local-serving retail up to 10,000 square feet would be screened from VMT analysis. The OPR guidance recommends screening local-serving retail from VMT analysis since they introduce a greater mix of services into the urban fabric, resulting in improved proximity of retail to many residents and thereby resulting in shorter trips and a reduction in total VMT. By contrast, regional-serving retail uses would tend to draw customers from longer distances, thereby increasing VMT.

The project as proposed would include approximately 4,000 square feet of retail space. Given the size of this use and the location of the site, it is expected that the retail would be local serving, as it would primarily cater to residents of the project and other existing and future residents within walking distance of the site as well as drivers traveling to Downtown Cotati. Since the proposed retail uses would be local serving, it is assumed that they would not result in an increase in total VMT and could therefore be screened from a more detailed VMT analysis.

Significance Finding – The project would screen out from quantitative analysis and is presumed to have a lessthan-significant impact on VMT. 19 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Safety Issues
The potential for the project to impact safety was evaluated in terms of the adequacy of sight distance and need for turn lanes at the project access as well as the adequacy of stacking space in dedicated turn lanes at the study intersections to accommodate additional queuing due to adding project-generated trips and need for additional right-of-way controls. This section addresses the third transportation bullet on the CEQA checklist which is whether or not the project would substantially increase hazards due to a geometric design feature (e.g., sharp curves or dangerous intersections) or incompatible uses (e.g., farm equipment).

Site Access
The project as proposed would be accessed via two new driveways, including one on East Cotati Avenue and one on Charles Street. Both are proposed with full access, with the one on East Cotati Avenue having the benefit of the existing two-way left-turn lane. Per staff’s request, potential alternative access schemes that include eliminating one or the other driveway and/or limiting movements at the East Cotati Avenue driveway were evaluated.

Sight Distance
Sight distance along East Cotati Avenue at the project driveway was evaluated based on sight distance criteria contained in the Highway Design Manual published by Caltrans. There is no recommended sight distance for urban driveways; however, stopping sight distance was evaluated for safety reasons, with the approach travel speeds used as the basis for determining the recommended sight distance. Additionally, the stopping sight distance needed for a following driver to stop if there is a vehicle waiting to turn into a side street or driveway was evaluated based on stopping sight distance criterion and the approach speed on the major street. Based on a design speed of 30 mph, the minimum stopping sight distance needed is 200 feet. Based on field measurements, drivers traveling east have 200 feet or more of sight distance to vehicles slowing to turn into the project driveway.

Stopping sight distance is not applicable to westbound traffic as vehicles turning left into the project driveway could use the two-way left-turn lane on East Cotati Avenue. Sight distance would therefore be adequate to allow all movements at the driveway, though parked vehicles could impede sight lines. Parking should therefore be prohibited within 25 feet of the driveway if egress at this location is permitted.

Though Charles Street has no posted speed limit, it has a prima facie speed limit of 25 mph as a local residential street. The stopping sight distance for vehicles traveling north is greater than the 150 feet minimum. For vehicles traveling south on Charles Street, the available stopping sight distance of approximately 125 feet would be adequate due to vehicles approaching at a lower speed after making the turn onto Charles.

Lane Merge
Eastbound traffic on East Cotati Avenue merges from two lanes at Old Redwood Highway to one lane at La Plaza.

While the merge is proximate to the project site, vehicles must enter a single lane prior to reaching the project’s frontage and the proposed driveway location. As a result, drivers approaching the proposed driveway location would typically be focusing on the road ahead of them rather than looking to the side for merging traffic. Given that the merge would be complete prior to driveway, the driveway can reasonably be expected to operate acceptably and in a manner similar to that of nearby driveways on both sides of the street.

It is noted that staff has indicated a preference for limiting access to right-turns in and out. However, to ensure that turns are eliminated typically requires physical measures such as a median or delineators and such devices would affect turns in both directions, effectively eliminating left turns into and out of the properties on the north side of East Cotati Avenue as well. Given the lack of a demonstrated need to prohibit left turns, this approach is not recommended.
20 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Increased Volumes
Consideration was also given to the volume of traffic that would be added to Charles Street by the project. While it is generally a local residential street, most of the traffic associated with the project would be due to residents, so consistent with the use of the roadway. It is noted that volumes on Charles Street exceed what would be expected given the development served, likely due to drivers bypassing the intersection of East Cotati Avenue/Old Redwood Highway. The use of the road by drivers who should not be using the street should not, however, negate the rights of a property owner to access a site along the street, such as the proposed project.

Recommended Access Scheme
Based on the evaluation performed, it is anticipated that both proposed driveways can reasonably be expected to operate acceptably with full access, similar to other driveways on the two fronting streets. By allowing access to both streets the volume of project traffic will be spread between the two streets, thereby having a lesser effect on either. There does not appear to be a nexus for limiting access at the East Cotati Avenue driveway as the location is beyond the end of the merge from two lanes to one, so would not be affected by this movement.

Queuing
The City of Cotati does not prescribe thresholds of significance regarding queue lengths for unsignalized intersections. For signalized intersections, the City identifies only those wherein the queue length would extend into upstream signalized intersections, an inapplicable standard for the intersection of East Cotati Avenue/Old Redwood Highway due to all nearby intersections being unsignalized. However, an increase in queue length due to project traffic was considered a potentially significant impact if the increase would cause the queue to extend out of a dedicated turn lane into a through traffic lane, or the back of queue into a visually restricted area, such as a blind corner. If queues would already be expected to extend past a dedicated turn lane or into a visually restricted area without project traffic, the addition of project traffic was considered to constitute a potentially significant impact only if it would cause a new unacceptable condition; in other words, if the queue were already beyond the turn lane and the project would cause it to stack into an adjacent intersection or a visually restricted area, and that would not occur without the project, that would be considered an impact.

Under each scenario, the 95th percentile queue length projected by Synchro was used for signalized intersections.

Queues for unsignalized intersections were calculated using the methodology published in the ITE Journal, “Estimating Maximum Queue Length at Unsignalized Intersections,” John T. Gard, 2001. Summarized in Table 6 are the predicted queue lengths for the study intersections with turning lanes. Copies of the Synchro projections and unsignalized intersection queue calculations are contained in Appendix B. 21 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Table 6 – Maximum Queues in Dedicated Left-Turn Lanes
Study Intersection
Turn Lane
Available
Storage
Maximum Queues
AM Peak Hour PM Peak Hour
E E+P F F+P E E+P F F+P
E. Cotati Ave/ORH
NB Left turn 95 21 16 16 16 21 21 23 23
SB Left turn 290 149 157 239 239 215 218 261 262
EB Left turn 160 87 84 84 84 114 114 118 118
E. Cotati Ave/Charles St
WB Left turn 280 100 125 150 150 75 75 100 125
Notes: Maximum Queue based on the Synchro HCM6 Queueing; all distances are measured in feet; E = Existing Conditions; E+P = Existing plus Project Conditions; F = Future Conditions; F+P = Future plus Project Conditions Queues would not exceed storage capacity at the intersection of East Cotati Avenue/Old Redwood Highway with or without project volumes under for any scenario evaluated.

Finding – The project does not cause any queues to exceed available storage, so the impact is considered lessthan-significant.

Significance Finding – The proposed project would not create any new hazards or introduce incompatible uses to the roadway system, so its impact on safety would be less than significant. 22 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Emergency Access
The final transportation bullet on the CEQA checklist requires an evaluation as to whether the project would result in inadequate emergency access or not.

Adequacy of Site Access
Three sides of the project would be accessible to emergency vehicles via the surrounding street network, including East Cotati Avenue, La Plaza, and Charles Street. According to the site plan, the driveways and drive aisles would be designed to a minimum width of 25 feet. The addition of sidewalk and parking on Charles Street would not reduce available space to the point where emergency vehicles such as fire trucks could not access the site. It is anticipated that all aspects of the site would be constructed in accordance with applicable standards and would be reviewed by the Fire Department; therefore, access would be expected to function acceptably for emergency response vehicles.

Off-Site Impacts
While the project would be expected to result in a minor increase in delay for traffic on East Cotati Avenue or Charles Street, emergency response vehicles can claim the right-of-way by using their lights and sirens; therefore, the project would be expected to have a nominal effect on emergency response times.

Significance Finding – The proposed project would be designed to accommodate emergency response vehicles and would not impede emergency responders, resulting in a less-than-significant impact on emergency response. 23 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Capacity Analysis
Intersection Level of Service Methodologies
Level of Service (LOS) is used to rank traffic operation on various types of facilities based on traffic volumes and roadway capacity using a series of letter designations ranging from A to F. Generally, Level of Service A represents free flow conditions and Level of Service F represents forced flow or breakdown conditions. A unit of measure that indicates a level of delay generally accompanies the LOS designation.

The study intersections were analyzed using methodologies published in the Highway Capacity Manual (HCM), Transportation Research Board, 2010. This source contains methodologies for various types of intersection control, all of which are related to a measurement of delay in average number of seconds per vehicle.

The Levels of Service for the intersections with side street stop controls, or those which are unsignalized and have one or two approaches stop controlled, were analyzed using the “Two-Way Stop-Controlled” intersection capacity method from the HCM. This methodology determines a level of service for each minor turning movement by estimating the level of average delay in seconds per vehicle. Results are presented for individual movements together with the weighted overall average delay for the intersection.

The study intersection of East Cotati Avenue/Old Redwood Highway is controlled by a traffic signal so was evaluated using the signalized methodology from the HCM. This methodology is based on factors including traffic volumes, green time for each movement, phasing, whether the signals are coordinated or not, truck traffic, and pedestrian activity. Average stopped delay per vehicle in seconds is used as the basis for evaluation in this LOS methodology. For purposes of this study, delays were calculated using signal timing obtained from the City of Cotati. The ranges of delay associated with the various levels of service are indicated in Table 7.

Table 7 – Intersection Level of Service Criteria
LOS Two-Way Stop-Controlled Signalized
A Delay of 0 to 10 seconds. Gaps in traffic are readily available for drivers exiting the minor street.

Delay of 0 to 10 seconds. Most vehicles arrive
during the green phase, so do not stop at all.

B Delay of 10 to 15 seconds. Gaps in traffic are
somewhat less readily available than with LOS A, but
no queuing occurs on the minor street.

Delay of 10 to 20 seconds. More vehicles stop than
with LOS A, but many drivers still do not have to
stop.

C Delay of 15 to 25 seconds. Acceptable gaps in traffic are less frequent, and drivers may approach while
another vehicle is already waiting to exit the side
street.

Delay of 20 to 35 seconds. The number of vehicles
stopping is significant, although many still pass
through without stopping.

D Delay of 25 to 35 seconds. There are fewer acceptable gaps in traffic, and drivers may enter a queue of one or two vehicles on the side street.

Delay of 35 to 55 seconds. The influence of
congestion is noticeable, and most vehicles have to
stop.

E Delay of 35 to 50 seconds. Few acceptable gaps in
traffic are available, and longer queues may form on
the side street.

Delay of 55 to 80 seconds. Most, if not all, vehicles
must stop and drivers consider the delay excessive.

F Delay of more than 50 seconds. Drivers may wait for
long periods before there is an acceptable gap in
traffic for exiting the side streets, creating long queues.

Delay of more than 80 seconds. Vehicles may wait
through more than one cycle to clear the
intersection.

Reference: Highway Capacity Manual, Transportation Research Board, 2010 24 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Traffic Operation Standards
According to the Cotati General Plan, Policy C1 1.3, the minimum acceptable Level of Service (LOS) standard for intersections is LOS D. At unsignalized intersections, levels of service shall be determined for both controlled movements and for the intersection overall. An adverse traffic-related effect would occur if implementation of the project would cause an intersection to operate below the General Plan’s standard of LOS D, or LOS E for intersections within the boundaries of the Downtown Cotati Specific Plan, which includes the project site and study intersections.

At unsignalized intersections, controlled movements operating at LOS E or LOS F are allowable if

1. The intersection is projected to operate at LOS C or better overall, and

2. The projected traffic volume on the controlled movement is 30 vehicles or less per hour on approaches with single lanes, or on multi-lane approaches, 30 vehicles or less per hour on lanes serving left turns and through movements.

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. Under Existing Conditions, all study intersections are operating at an overall LOS of C or higher. While the northbound approach of Charles Street currently operates at LOS E during the evening peak hour, this is acceptable as the site is within the Downtown Cotati Specific Plan area. The existing traffic volumes are shown in Figure 3. A summary of the intersection Level of Service calculations is contained in Table 8, and copies of the calculations are provided in Appendix C.

Table 8 – Existing Peak Hour Intersection Levels of Service Study Intersection
Approach
AM Peak PM Peak
Delay LOS Delay LOS

1. E. Cotati Ave/Old Redwood Hwy/ 26.7 C 22.8 C

2. E. Cotati Ave/La Plaza 0.1 A 0.2 A
Northbound (La Plaza) Approach 10.2 B 11.8 B
Southbound (La Plaza) Approach 15.4 C 12.0 B

3. E. Cotati Ave/Charles St 2.0 A 4.7 A
Northbound (Charles St) Approach 15.2 C 37.5 E
Note: Delay is measured in average seconds per vehicle; LOS = Level of Service; Results for minor approaches to two-way stop-controlled intersections are indicated in italics
Future Conditions
Segment volumes for the horizon year of 2040 were obtained from the County’s gravity demand model and translated to turning movement volumes at each of the study intersections using a combination of the “Furness” method and factoring, depending on how the model was configured at each intersection. The Furness method is an iterative process that employs existing turn movement data, existing link volumes and future link volumes to project likely turning future movement volumes at intersections. Segment growth rates for La Plaza and Charles Transportation Impact Study for the 120 East Cotati Avenue Residential Project cot092-4.ai 2/25
North
Not to Scale
Old Redwood Hwy
E Cotati Ave
Arthur St
Charles St
La Plaza
1 2
3 Project Site
Figure 3 – Existing and Future Traffic Volumes
(xx) PM Peak Hour Volume
xx AM Peak Hour Volume
Study Intersection
LEGEND
24(9)795(542)
(876)552
2(4)
(21)9
2 Existing
820(549)179(89)
(7)5
(888)554
(2)1
(191)110
3 Existing
480(565)380(270)
(4)3
(357)303
(82)64
44(66)
341(344)
578(660)
(13)8
(401)323
(107)31
1 Future
412(313)377(232)
(4)3
(350)226
(82)64
44(66)
285(344)
322(519)
(13)8
(357)323
(10)1
1 Existing
27(11)940(859)
(1118)915
2(5)
(28)10
2 Future
960(850)205(135)
(63)37
(1107)894
(17)5
(218)133
3 Future
26 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Street were developed based on those for East Cotati Avenue due to the County model lacking values for minor streets in the gravity demand model.

Under the anticipated future volumes, the unsignalized study intersections are expected to operate similarly though with an increase in delay and the controlled approaches experiencing deterioration in LOS. The signalized intersection of East Cotati Avenue/Old Redwood Highway would be expected to operate at LOS E during the p.m. peak hour. Future volumes are shown in Figure 3 and operating conditions are summarized in Table 9.

Table 9 – Future Peak Hour Intersection Levels of Service Study Intersection
Approach
AM Peak PM Peak
Delay LOS Delay LOS

1. E. Cotati Ave/Old Redwood Hwy 32.6 C 58.0 E

2. E. Cotati Ave/La Plaza 0.1 A 0.2 A
Northbound (La Plaza) Approach 11.7 B 13.1 B
Southbound (La Plaza) Approach 16.6 C 15.4 C

3. E. Cotati Ave/Charles St 2.8 A 12.9 B
Northbound (Charles St) Approach 27.1 D 123.3 F
Note: Delay is measured in average seconds per vehicle; LOS = Level of Service; Results for minor approaches to two-way stop-controlled intersections are indicated in italics; Bold text = deficient operation Operation at the intersection of East Cotati Avenue/Old Redwood Highway would deteriorate from LOS C to LOS E; however, because the intersection lies within the Downtown Cotati Specific Plan area, this would be considered acceptable. The controlled northbound approach of East Cotati Avenue/Charles Street would deteriorate from LOS E to LOS F with future volumes, resulting in unacceptable operation per the City’s standards. It is noted that the delay is associated primarily with the 17 left turns; prohibition of left turns at this location would decrease delay but the approach would continue to operate at an unacceptable LOS F. The City may wish to monitor this location as volumes increase to determine when the left-turn prohibition should be implemented. It is noted that the right-turning volume on this approach results from northbound drivers on Old Redwood Highway bypassing the intersection of East Cotati Avenue/Old Redwood Highway. Should future volumes meet projections and delay increase as projected, drivers may cease use of Charles Street if it results in longer travel times.

Project Conditions
Existing plus Project Conditions
Project traffic volumes are shown in Figure 4. Upon the addition of project-related traffic to the existing volumes, the study intersections are expected to continue operating acceptably at the same service levels though with some increase in delay at each intersection. These results are summarized in Table 10.

Transportation Impact Study for the 120 East Cotati Avenue Residential Project cot092-4.ai 2/25
North
Not to Scale
Old Redwood Hwy
E Cotati Ave
Arthur St
Charles St
La Plaza
1 2
3 Project Site
Figure 4 – Project Traffic Volumes
(xx) PM Peak Hour Volume
xx AM Peak Hour Volume
Study Intersection
LEGEND
6(2)
(5)2
2 1(3)
(2)5
(2)6
(191)110
3 4(1)
2(1)
(2)1
1(3)
1 28 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Table 10 – Existing and Existing plus Project Peak Hour Intersection Levels of Service Study Intersection
Approach
Existing Conditions Existing plus Project
AM Peak PM Peak AM Peak PM Peak
Delay LOS Delay LOS Delay LOS Delay LOS

1. E. Cotati Ave/Old Redwood Hwy 26.7 C 22.8 C 24.3 C 23.0 C

2. E. Cotati Ave/La Plaza 0.1 A 0.2 A 0.1 A 0.2 A
Northbound (La Plaza) Approach 10.2 B 11.8 B 10.2 B 11.8 B Southbound (La Plaza) Approach 15.4 C 12.0 B 15.5 C 12.0 B

3. E. Cotati Ave/Charles St 2.0 A 4.7 A 2.3 A 5.0 A
Northbound (Charles St) Approach 15.2 C 37.5 E 17.0 C 38.9 E Note: Delay is measured in average seconds per vehicle; LOS = Level of Service; Results for minor approaches to two-way stop-controlled intersections are indicated in italics
It should be noted that with the addition of project-related traffic volumes, average delay at the intersection of East Cotati Avenue/Old Redwood Highway decreases during the a.m. peak hour. While this is counter-intuitive, this condition occurs when a project adds trips to movements that are currently underutilized or have delays that are below the intersection average, resulting in a better balance between approaches and lower overall average delay. The project adds traffic predominantly to the westbound right-turn movement, which has an average delay that is lower than the average for the intersection as a whole, resulting in a slight reduction in the overall average delay. The conclusion could incorrectly be drawn that the project actually improves operation based on this data alone; however, it is more appropriate to conclude that the project trips are expected to make use of excess capacity, so drivers will experience little, if any, change in conditions as a result of the project.

Finding – The study intersections would continue operating acceptably upon adding project-generated trips to existing volumes.

Future plus Project Conditions
Upon the addition of project-generated traffic to the anticipated future volumes, the study intersections are expected to operate similarly, with no further deterioration in LOS. The Future plus Project operating conditions are summarized in Table 11.

Table 11 – Future and Future plus Project Peak Hour Intersection Levels of Service Study Intersection
Approach
Future Conditions Future plus Project
AM Peak PM Peak AM Peak PM Peak
Delay LOS Delay LOS Delay LOS Delay LOS

1. E. Cotati Ave/Old Redwood Hwy 32.6 C 58.0 E 33.1 C 58.3 E

2. E. Cotati Ave/La Plaza 0.1 A 0.2 A 0.1 A 0.2 A
Northbound (La Plaza) Approach 11.7 B 13.1 B 11.7 B 13.1 B Southbound (La Plaza) Approach 16.6 C 15.4 C 16.7 C 15.4 C

3. E. Cotati Ave/Charles St 2.8 A 12.9 B 3.1 A 13.5 B
Northbound (Charles St) Approach 27.1 D 123.3 F 31.1 D 129.5 F Note: Delay is measured in average seconds per vehicle; LOS = Level of Service; Results for minor approaches to two-way stop-controlled intersections are indicated in italics; Bold text = deficient operation 29 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
The northbound approach of East Cotati Avenue/Charles Street would operate at an unacceptable LOS F during the p.m. peak period without or with project volumes. Project volumes would, however, increase the average delay by 6.2 seconds during the p.m. peak hour. As noted for Future Conditions, prohibiting left turns from Charles Street would decrease delay but not improve LOS to an acceptable level.

Finding – The project would not cause intersection delay to deteriorate to an unacceptable LOS E or F and therefore would not have an adverse effect on operation based on City policy, though delay would increase. 30 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Parking
The project was analyzed to determine whether the proposed parking supply would be sufficient for the anticipated parking demand. The project site as proposed would include a garage on the first floor with a total of 54 standard parking spaces. For on-street parking, two to three spaces would be removed on both East Cotati Avenue and Charles Street to accommodate the project driveways. Four on-street parking spaces on Charles Street would be formalized through the construction of the sidewalk, resulting in a net loss of zero to two on-street parking spaces.

Parking supply requirements are based on the Downtown Cotati Specific Plan, 2009. Based on the project’s different uses, the site would require 100 spaces. However, the project qualifies for California Government Code 65915, also known as the State Density Bonus Law, and as such the requirement is a maximum of one space per studio or onebedroom unit, one and one-half spaces per two- and three-bedroom units, and no parking minimum for retail. In addition, the project would be entitled to a reduced number of required parking spaces based on Assembly Bill 2162. Based on application of these various policies, a total of 42 parking spaces would be required, which is 12 spaces less than the supply as proposed.

The proposed parking supply and City requirements are shown in Table 12.

Table 12 – Parking Analysis Summary
Land Use Units Supply
(spaces)
City Requirements State Density Bonus
Law
AB 2162
Rate Spaces
Required
Rate Spaces
Required
Rate Spaces
Required
Studio & 1 bdr 21 du 54 2.0 spaces
per unit
42 1.0 spaces
per unit
21 1.0 spaces
per unit*
13 2 bdr & 3 bdr 23 du 0 2.0 spaces
per unit
26 1.5 spaces
per unit
35 1.5 spaces
per unit*
29 Retail 3.85 ksf 0 3.0 spaces
per 1.0 ksf
12 n/a 0 n/a 0
Total 54 100 56 42
Note: *12 supportive units do not require parking; du = dwelling unit; ksf = 1,000 square feet While parking for the retail component is not required, it is noted that residential and retail parking can both be served by the same supply during much of the time as residents are typically not at home during the day when retail activity is at its peak. To achieve the most efficient use of the proposed parking supply, consideration should be given to not assigning any parking spaces to individual units. This would be expected to make parking spaces available for retail use.

The site plan shows that out of the 54 spaces proposed for residential use, there would be four accessible stalls and thirteen EV stalls. The City of Cotati Municipal Code, Chapter 21.28; Parking and Loading, requires that parking spaces for the disabled must be provided in compliance with the uniform building code and the Federal Accessibility Guidelines. Based on requirements stipulated by the Federal Accessibility Guidelines, the required number of accessible stalls is three stalls for the residential portion of the project. The proposed accessible stall supply is adequate to meet this requirement.
31 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
City parking stall sizes are based on the City of Cotati Municipal Code, Chapter 17.36; Parking and Loading. Required parking stall sizes for the City of Cotati are 9 feet by 18 feet. According to the site plan, regular parking stall sizes as proposed would be approximately 9 feet by 20 feet, which would meet the City’s requirement.

Finding – The proposed parking supply would be adequate based on the State Density Bonus Law and its inclusion of supportive units.

32 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Conclusions and Recommendations
Conclusions
• Existing pedestrian facilities would be enhanced through the improvement of sidewalks on East Cotati Avenue and the addition of sidewalk on Charles Street.
• The project would not affect bicycle right-of-way for either existing or planned bicycle facilities. Sufficient bicycle parking would be provided based on City Code.
• The project would not conflict with any policies regarding transportation facilities and thus would have a lessthan-significant impact on these facilities. • Roadway facilities would not be impacted by the addition and improvement of sidewalk on East Cotati Avenue. Restriping on East Cotati Avenue would be required to accommodate the wider sidewalk proposed as part of the project.
• Based on a five-year study period, two of the three study intersections had collision rates lower than the statewide average. The one location with an above-average crash rate had a pattern of rear-end crashes, three out of four of them occurred on the stop-controlled northbound approach, so no remedial action appears necessary. No crashes involving pedestrians or bicyclists were reported during the study period. • The project as proposed is expected to generate an average of 277 new daily trips with 19 trips occurring during the a.m. peak hour and 16 trips occurring during the p.m. peak hour. • The project would screen out from quantitative analysis and is therefore presumed to have a less-thansignificant impact on VMT. • Sight lines at the project driveways on East Cotati Avenue and Charles Street are adequate. • The project would not cause any queues to exceed available stacking space, so the project’s impact on safety would be less than significant.
• Assuming it is designed to meet applicable codes and policies, the proposed project would have a less-thansignificant impact on emergency response. • The study intersections are currently operating acceptably. The project would not cause study intersections’ service level to decrease due to adding project-generated trips to existing volumes. • The northbound approach of East Cotati Avenue/Charles Street would experience increases in delay and deterioration of LOS under future volumes. The addition of project-generated trips would not cause the service level to decrease at any of the study intersections to an unacceptable level. • Based on the State Density Bonus Law and the inclusion of supportive units, the proposed parking supply is sufficient.

Recommendations
• Reconfigure East Cotati Avenue to accommodate the additional sidewalk width. 33 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
• The City may wish to consider prohibiting left turns from Charles Street to East Cotati Avenue in the future if volumes reach the level projected by the model.
• Consideration should be given to having no spaces designated for specific users to make more efficient use of the parking supply.
34 Transportation Impact Study for the 120 East Cotati Avenue Residential Project April 3, 2025
Study Participants and References
Study Participants
Principal in Charge Dalene J. Whitlock, PE (Civil, Traffic), PTOE Assistant Engineer Gabriel Ramos, EIT
Graphics Jessica Bender
Editing/Formatting Rebecca Mansour
Quality Control Dalene J. Whitlock, PE (Civil, Traffic), PTOE References
“Estimating Maximum Queue Length at Unsignalized Intersections,” ITE Journal, John T. Gard, November 2001 2022 Crash Data on California State Highways, California Department of Transportation, 2024 California Manual on Uniform Traffic Control Devices for Streets and Highways Revision 6, California Department of Transportation, 2021
City of Cotati Active Transportation Plan, Sonoma County Transportation Authority, 2024 Cotati Bicycle & Pedestrian Master Plan, Sonoma County Transportation Authority, 2014 Cotati General Plan, De Novo Planning Group, 2015
Cotati Hotel Project Transportation Impact Analysis, TJKM, 2019 Cotati Municipal Code, Code Publishing Company, 2017
Downtown Cotati Specific Plan, City of Cotati, 2009
Golden Gate Transit, http://goldengatetransit.org/schedules/current/ Guide for the Preparation of Traffic Impact Studies, California Department of Transportation, 2002 Guidelines for Analysis of Vehicle Miles Traveled (VMT), City of Cotati, 2020 Handbook for Analyzing Greenhouse Gas Emission Reductions, Assessing Climate Vulnerabilities, and Advancing Health and Equity: Designed for Local Governments, Communities, and Project Developers, California Air Highway Capacity Manual, Transportation Research Board, 2010 Highway Design Manual, 7th Edition, California Department of Transportation, 2020 Intersection Channelization Design Guide, National Cooperative Highway Research Program (NCHRP) Report No. 279, Transportation Research Board, 1985
Method for Prioritizing Intersection Improvements, Washington State Transportation Center, 1997 Handbook for Analyzing Greenhouse Gas Emission Reductions, Assessing Climate Vulnerabilities, and Advancing Health and Equity: Designed for Local Governments, Communities, and Project Developers, California Air Pollution Control Officers Association (CAPCOA), 2021
Sonoma County Transit, http://sctransit.com/
Sonoma-Marin Area Rail Transit, http://www.sonomamarintrain.org/ Statewide Integrated Traffic Records System (SWITRS), California Highway Patrol, 2020-2024 Traffic Impact Fee Study, W-Trans, 2015
Transportation Impacts (SB 743) CEQA Guidelines Update and Technical Advisory, Governor’s Office of Planning and Research, 2018
Trip Generation Manual, 11th Edition, Institute of Transportation Engineers, 2021 COT092
A Transportation Impact Study for the East Cotati Avenue Residential Project April 2025
Appendix A
Collision Rate Calculations

Date of Count:

Number of Collisions: 9
Number of Injuries: 4
Number of Fatalities: 0
Average Daily Traffic (ADT): 22900
Start Date:

End Date:

Number of Years: 5
Intersection Type: Four-Legged
Control Type: Signals
Area: Urban
9 x
22,900 x x 5
Study Intersection 0.22 c/mve
Statewide Average* 0.33 c/mve
Notes
c/mve = collisions per million vehicles entering intersection * 2022 Collision Data on California State Highways, Caltrans Date of Count:

Number of Collisions: 3
Number of Injuries: 0
Number of Fatalities: 0
Average Daily Traffic (ADT): 14600
Start Date:

End Date:

Number of Years: 5
Intersection Type: Four-Legged
Control Type: Stop & Yield Controls
Area: Urban
3 x
14,600 x x 5
Study Intersection 0.11 c/mve
Statewide Average* 0.20 c/mve
Notes
c/mve = collisions per million vehicles entering intersection * 2022 Collision Data on California State Highways, Caltrans East Cotati Avenue Residential Project
Tuesday, January 28, 2025
Tuesday, January 28, 2025

47.5%
Number of Collisions x 1 Million Collision Rate =
1:

Collision Rate
Intersection Collision Rate Worksheet
January 1, 2020
December 31, 2024
Intersection # Old Redwoody Hwy & E Cotati Ave
Collision Rate = 1,000,000
E Cotati Ave & La Plaza

47.7%
ADT = average daily total vehicles entering intersection January 1, 2020
365
Intersection #
December 31, 2024
Collision Rate =
365
2:

Number of Collisions x 1 Million

0.6%
Collision Rate =
ADT x Days per Year x Number of Years

44.4%
1,000,000
Fatality Rate Injury Rate

0.0%

0.0%
Collision Rate Fatality Rate
ADT x Days per Year x Number of Years
Injury Rate

0.0%
ADT = average daily total vehicles entering intersection

1.1%
W-Trans
3/13/2025

Page 1 of 2 ends

Date of Count:

Number of Collisions: 6
Number of Injuries: 4
Number of Fatalities: 0
Average Daily Traffic (ADT): 17300
Start Date:

End Date:

Number of Years: 5
Intersection Type: Tee
Control Type: Stop & Yield Controls
Area: Urban
6 x
17,300 x x 5
Study Intersection 0.19 c/mve
Statewide Average* 0.13 c/mve
Notes
c/mve = collisions per million vehicles entering intersection * 2022 Collision Data on California State Highways, Caltrans

47.3%
365
Collision Rate
Collision Rate = 1,000,000
Injury Rate

0.0%
East Cotati Avenue Residential Project
January 1, 2020
3: E Cotati Ave & Charles St
Collision Rate = Number of Collisions x 1 Million
ADT x Days per Year x Number of Years
December 31, 2024
ADT = average daily total vehicles entering intersection

1.3%
Tuesday, January 28, 2025

66.7%
Intersection Collision Rate Worksheet
Intersection #
Fatality Rate
W-Trans
3/13/2025

Page 2 of 2 ends

B Transportation Impact Study/Analysis for the 120 East Cotati Avenue Residential Project April 2025
Appendix B
Queueing Calculations

Queues
1: Old Redwood Highway & West Sierra Avenue/East Cotati Avenue 02/19/2025

1. Existing AM Synchro 11 Report
Transportation Impact Study for the 120 East Cotati Avenue Residential Project Page 1 Lane Group EBL EBT EBR WBT WBR NBL NBT SBL SBT
Lane Group Flow (vph) 69 243 3 408 443 9 348 346 353
v/c Ratio 0.31 0.32 0.00 0.78 0.59 0.04 0.44 0.58 0.70
Control Delay 39.7 16.0 0.0 36.8 6.5 37.2 27.2 34.6 31.3 Queue Delay 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Total Delay 39.7 16.0 0.0 36.8 6.5 37.2 27.2 34.6 31.3
Queue Length 50th (ft) 28 62 0 159 0 4 70 73 138
Queue Length 95th (ft) 87 162 0 #379 76 21 128 149 243
Internal Link Dist (ft) 185 194 945 784
Turn Bay Length (ft) 160 145 200 95 290
Base Capacity (vph) 232 1155 968 795 901 414 1625 992 966 Starvation Cap Reductn 0 0 0 0 0 0 0 0 0
Spillback Cap Reductn 0 0 0 0 0 0 0 0 0
Storage Cap Reductn 0 0 0 0 0 0 0 0 0
Reduced v/c Ratio 0.30 0.21 0.00 0.51 0.49 0.02 0.21 0.35 0.37 Intersection Summary
# 95th percentile volume exceeds capacity, queue may be longer.