-2022.0201.PR0004 2021-1118 Berry Valley Traffic Scoping
8730 Tallon Lane NE, Suite 200 Lacey, WA 98516 Office 360.352.1465 Fax 360.352.1509 scjalliance.com
Technical Memo
To City of Yelm
From: Ryan Shea, Senior Transportation Planner
Date: November 23, 2021
Project: Berry Valley Townhomes (#21-000227)
Subject Traffic Scoping Analysis
Introduction
Matthew Gerrish is proposing to develop the Berry Valley Townhomes project to be located at 14747 Berry
Valley Road SE, Yelm, WA. The proposed development would include up to 70 residential units. Figure 1
illustrates the site vicinity and the transportation network serving the project area.
This Traffic Scoping Analysis estimates the trip generation, distribution, and assignment for the proposed
development.
Figure 1. Site Vicinity
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Proposed Development
The Berry Valley Townhomes project is located at 14747 Berry Valley Road SE, in Yelm, WA. The existing zoning
for the project site allows for the same number of multi-family units as single-family homes. The project is
proposing a zoning change to allow for all multi-family units. This scoping letter provides a trip generation of
both scenarios.
Based on current zoning, the proposed project would construct 26 townhome units and 27 single family homes.
If the proposed zoning changes are accepted, the proposed project would construct 70 townhome units. The
site has an existing single-family residence that will be removed, resulting in a net increase of 26 single family
homes for the current zoning scenario and a trip reduction for the proposed zoning scenario. Access to the site
will be provided by two full access driveways on Berry Valley Road SE. The project is anticipated to open in 2022.
The preliminary site plan is attached.
Project Traffic Characteristics
The two project-related characteristics having the most effect on area traffic conditions are peak hour trip
generation and the directional distribution of traffic volumes on the surrounding roadway network. These are
discussed in the following paragraphs.
Site-Generated Traffic Volumes
Vehicle trip generation was estimated using the trip generation rates contained in the 11th edition of the Trip
Generation Manual by the Institute of Transportation Engineers (ITE). The land-use category “Single-Family
Detached Housing” (land-use code 210) was determined to be the best fit for the single-family homes and the
land use category “Single Family Attached Housing (land use code 215) was determined to be the best fit for the
townhome units. For this analysis, the “fitted-curve” equation was used for both land use categories to estimate
trips in preference to using a specific trip rate as this approach was recommended by ITE
The trip generation rates used for the PM peak hour for the existing zoning scenario are shown in Table 1. The
trip generation rates used for the proposed zoning scenario are shown in Table 2. Trip generation calculations
are attached, including AM peak hour and Daily.
Table 1. PM Peak Hour Trip Generation Rates - Existing Zoning Scenario
Land Use
Land Use
Code (LUC) Unit
Trip
Rate Enter % Exit %
Single Family Attached Housing 215 Dwelling
Units 0.45 57% 43%
Single-Family Detached Housing 210 Dwelling
Units 1.08 63% 37%
Berry Valley Townhomes Traffic Scoping Analysis 2021-1123 | 3 of 4
Table 2. PM Peak Hour Trip Generation Rates - Proposed Zoning Scenario
Land Use
Land Use
Code (LUC) Unit
Trip
Rate Enter % Exit %
Single Family Attached Housing 215 Dwelling
Units 0.54 57% 43%
Single-Family Detached Housing 210 Dwelling
Units 1.31 63% 37%
The total trip generation expected from this project is calculated by applying the unit measure for each land use
category to the appropriate trip generation rate. The existing zoning trip generation calculations are shown in
Table 3 and the proposed zoning trip generation calculations are shown in Table 4.
Table 3. Project Trip Generation - Existing Zoning
Site Plan Description Size
Total
Trips Enter Exit
Townhomes 26 12 7 5
Single Family Homes 26* 28 18 10
Total 40 25 15
*Single-family home net increase
Table 4. Project Trip Generation – Proposed Zoning
Site Plan Description Size
Total
Trips Enter Exit
Townhomes 70 38 22 16
Single Family Homes* 1 1* 1 0
Total 37 21 16
*Existing single family home trip reduction
Site Traffic Distribution and Assignment
For this study, the regional distribution of traffic to and from the proposed project was estimated using the
regional transportation model developed by the Thurston Regional Planning Council (TRPC) in cooperation with
the local jurisdictions in Thurston County. The model uses the Emme/4 software package and has been
calibrated to represent the existing vehicle travel patterns throughout the entire county.
Using the model, a Select Link Analysis (SLA) was conducted for Tahoma Boulevard SE, west of the project site.
This feature of the Emme/4 software package allows all of the traffic on a particular roadway link to be isolated
and shown separately from the rest of the traffic on the network. The SLA graphically shows the percentage of
vehicles currently using each of the available routes into and out of the area (Yelm Avenue and Tahoma
Boulevard SE). From this information, regional distribution percentages were calculated for future traffic from
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the proposed Berry Valley Townhomes project. Since the existing zoning scenario provides a higher trip
generation, it was used for the site traffic distribution. The regional traffic distribution percentages and site
traffic distribution for the PM peak hour are shown on Figure 2. The select link analysis plot is attached.
Thank you for reviewing the enclosed materials which we have prepared to assist you in determining if further
traffic analysis will be warranted.
If you have any questions or comments about the enclosed information, please contact me at (360) 352-1465.
Respectfully,
SCJ Alliance
Ryan Shea, PTP
Transportation Planner
Enclosures: Figure 2
Trip Generation Calculations
Select Zone Analysis Plot
Preliminary Site Plan
N:\Projects\5183 Matthew Gerrish\21-000227 Berry Valley Townhomes Plat\Phase 04 - Traffic Scoping Report\Design\Traffic\2021-1118 Berry Valley
Traffic Scoping.docx
Berry Valley TownhomesTraffic Scoping AnalysisYelm, WashingtonProjectSiteTahoma Blvd SELongmire St SE W Yelm Ave
Berry Valley Rd SE2 3154813Figure 2Site-Generated Traffic VolumesPM Peak Hour1) Tahoma Blvd SE atBerry Valley Road SE2) Tahoma Blvd SE atW Yelm Ave133) Longmire St SE atW Yelm Ave4) Sorth Driveway atBerry Valley Road SE5) North Driveway atBerry Valley Road SE313222823213520529951275LegendXX%Primary Trip DistribuƟon PercentageXXSite-Generated Traffic VolumesProject TripsInboundOutboundTotal25 154053%46%N
Trip Generation
PM Peak Hour Trip Generation
In Out In Out Total
Townhomes 215 Single‐Family Attached Housing Dwelling units 26 0.45 57%43% 7 5 12
Single Family Homes 210 Single‐Family Detached Housing Dwelling units 26 1.08 63%37% 18 10 28
Total 25 15 40
215 Fitted Curve Equation 0.45
210 Fitted Curve Equation 1.08
AM Peak Hour Trip Generation
In Out In Out Total
Townhomes 215 Single‐Family Attached Housing Dwelling units 26 0.30 31%69% 2 6 8
Single Family Homes 210 Single‐Family Detached Housing Dwelling units 26 0.84 26%74% 6 16 22
Total 82230
215 Fitted Curve Equation 0.30
210 Fitted Curve Equation 0.84
Daily
In Out In Out Total
Townhomes 215 Single‐Family Attached Housing Dwelling units 26 5.68 50%50% 74 74 148
Single Family Homes 210 Single‐Family Detached Housing Dwelling units 26 11.24 50%50% 146 146 292
Total 220 220 440
215 Fitted Curve Equation 5.68
210 Fitted Curve Equation 11.24
PM Peak Hour Trip Generation
In Out In Out Total
Townhomes 215 Single‐Family Attached Housing Dwelling units 70 0.54 57%43% 22 16 38
Single Family Homes 210 Single‐Family Detached Housing Dwelling units 1 1.31 63%37% 1 0 1
Total 21 16 37
215 Fitted Curve Equation 0.54
210 Fitted Curve Equation 1.31
AM Peak Hour Trip Generation
In Out In Out Total
Townhomes 215 Single‐Family Attached Housing Dwelling units 70 0.44 31%69% 10 21 31
Single Family Homes 210 Single‐Family Detached Housing Dwelling units 1 1.13 26%74% 0 1 1
Total 10 20 30
215 Fitted Curve Equation 0.44
210 Fitted Curve Equation 1.13
Daily
In Out In Out Total
Townhomes 215 Single‐Family Attached Housing Dwelling units 70 6.90 50%50% 241 242 483
Single Family Homes 210 Single‐Family Detached Housing Dwelling units 1 14.59 50%50% 7 8 15
Total 234 234 468
215 Fitted Curve Equation 6.90
210 Fitted Curve Equation 14.59
Only Townhomes (70 Units)
Townhomes/Single Family Split (53 Units)
Total Trips
Berry Valley Townhomes Plat
Site Plan Description LUC ITE Description Variable Value Trip Rate
Distribution
Distribution Total Trips
Site Plan Description LUC ITE Description Variable Value Trip Rate
Distribution Total Trips
LUC ITE Description Variable Value Trip RateSite Plan Description
Trip Rate Distribution Total Trips
Site Plan Description LUC ITE Description Variable Value Trip Rate
Distribution Total Trips
Site Plan Description LUC ITE Description Variable Value
Trip Rate Distribution Total TripsSite Plan Description LUC ITE Description Variable Value
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