2023-1109 Yelm Starbucks Trip Gen
8730 Tallon Lane NE, Suite 200 Lacey, WA 98516 Office 360.352.1465 Fax 360.352.1509 scjalliance.com
Technical Memo
To Walker John, Urban Management Company, LLC
From: Ryan Shea, PTP
Date: November 9, 2023
Project: Yelm Starbucks – Tahoma Blvd
Subject Traffic Memo
Introduction
Urban Management Company, LLC is proposing to construct a new 6,300-square foot commercial building in
Yelm, Washington. This project is located at 125 Tahoma Boulevard SE within the Eagle Plaza commercial
development. This traffic memo identifies the potential traffic that could be added to the surrounding street
system by the proposed project, how the proposed project would fit within the previous traffic study for the
development, and how the site driveways will operate after completion of the project.
Figure 1 illustrates the site vicinity and the transportation network serving the project area.
Figure 1. Site Vicinity
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Proposed Development
The proposed project would construct a new 6,300-square foot building. The completed building will be
occupied by an approximate 2,300-square foot Starbucks and approximately 4,000 square feet of general
commercial space for future tenants. The project site is located on undeveloped land within the Eagle Plaza
commercial development. Existing access to the site is provided from Tahoma Boulevard and Yelm Avenue.
The preliminary site plan is attached.
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 “Coffee/Donut
Shop with Drive Through Window” (land-use code 937) and “Strip Retail Plaza (<40k)” (land-use code 822) were
determined to be the most applicable to this project.
Internal Capture
Internal capture calculations were prepared to reflect on-site interaction between the mix of existing uses and
the proposed project. These calculations would have been present in the original traffic study and are based on
the based on the methodology contained in the 3rd edition of the Trip Generation Handbook by ITE. This
calculation assumes only the existing uses and the proposed project. Additional internal capture assessments
are provided further in the report that include the potential Jimmy Johns development.
Pass-By
It is anticipated that this project will attract some traffic from people already driving on adjacent roadways.
These trips are not new trips added to the local roadway system (primary trips) but represent “pass-by” trips
according to the following definition:
Pass-by trips: Pass-by trips are trips made as an intermediate stop from an origin to a
primary destination (i.e., stopping to shop on the way home from work) by vehicles passing
directly by the project driveway.
Pass-by percentages for Shopping Center are provided in the 11th edition of the Trip Generation Manual for large
and medium sized commercial centers. No specific pass-by rate is provided for strip retail, so the pass-by rate for
the medium sized commercial land use category was used. No pass-by rate is provided for Coffee/Donut Shop
with Drive Through Window. To approximate the pass-by rate for this land use category an average of the pass-
by rates for Fast Food Restaurant with Drive Through Window and Coffee/Donut Shop with Drive Through
Window and No Indoor Seating was calculated. This resulted in a pass-by rate of 70% for the AM peak hour and
a pass-by rate of 75% for the PM peak hour..
The trip generation rates used for the AM peak hour are shown in Table 1, the PM peak hour rates are shown in
Table 2 and the Daily trip rates are shown in Table 3.
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Table 1. AM Peak Hour Trip Generation Rates
Land Use Category Land Use
Code (LUC) Unit Trip
Rate
Internal
Capture
Pass-By
Rate Enter % Exit %
Coffee/Donut Shop with Drive
Through Window 937 1,000-sqft 85.88 0% 70% 51% 49%
Strip Retail Plaza (<40k) 822 1,000-sqft 2.36 0% 0% 60% 40%
Table 2. PM Peak Hour Trip Generation Rates
Land Use Category Land Use
Code (LUC) Unit Trip
Rate
Internal
Capture
Pass-By
Rate Enter % Exit %
Coffee/Donut Shop with Drive
Through Window 937 1,000-sqft 38.99 16% 75% 52% 48%
Strip Retail Plaza (<40k) 822 1,000-sqft 9.41* 34% 40% 50% 50%
*Fitted curve equation rate
Table 3. Daily Trip Generation Rates
Land Use Category Land Use
Code (LUC) Unit Trip
Rate
Internal
Capture
Pass-By
Rate Enter % Exit %
Coffee/Donut Shop with Drive
Through Window 937 1,000-sqft 533.57 16% 70% 50% 50%
Strip Retail Plaza (<40k) 822 1,000-sqft 54.45 34% 40% 50% 50%
The total trip generation expected from this project is calculated by applying the unit measure (building square
footage) to the appropriate trip generation rate. The AM peak hour, PM peak hour and daily trip generation for
the proposed Yelm Starbucks are shown in Tables 4 through 6 below. The pass-by volumes are calculated based
on zero internal capture reduction. A discussion of internal capture is provided later in this memo.
Table 4. AM Peak Hour Project Trip Generation
Land Use Size Total
Trips
Internal
Capture Trips
Pass-By
Trips
New-to-
Network Total Enter Exit
Starbucks 2.3 198 0 139 59 30 29
General Commercial 4.0 9 0 0 9 5 4
Total Project Trips - 207 0 139 68 35 33
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Table 5. PM Peak Hour Project Trip Generation
Land Use Size Total
Trips
Internal
Capture Trips
Pass-By
Trips
New-to-
Network Total Enter Exit
Starbucks 2.3 90 14 57 19 9 10
General Commercial 4.0 41 14 11 16 8 8
Total Project Trips - 131 28 68 35 17 18
Table 6. Daily Project Trip Generation
Land Use Size Total
Trips
Internal
Capture Trips
Pass-By
Trips
New-to-
Network Total Enter Exit
Starbucks 2.3 1,227 196 722 309 154 155
General Commercial 4.0 218 74 58 86 43 43
Total Project Trips - 1,445 270 780 395 197 198
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 project area. 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 the proposed project. The project trip
assignment is provided in the attached traffic volume forecasts.
Previous Documentation
Mitigated Determination of Nonsignificance
The proposed project is part of a larger development that was studied in 2007. A Mitigated Determination of
Nonsignificance (MDNS) was issued by the city for the overall development on October 14, 2008, which
highlighted the traffic generated by the different development elements and the required mitigation. The MDNS
document is attached. There were four main elements to the overall development:
• Viewmont Place – Retail shopping complex located north of Yelm Avenue between Killion Road and
Mountain View Road. Expected to generate 820 PM peak hour trips.
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• Westmont Place – Retail shopping complex located north of Tahoma Boulevard across from Berry Valley
Road. Expected to generate 414 PM peak hour trips.
• Ritter Commercial Development – Mixed use retail and office development at the northwest corner of
Tahoma Boulevard and Yelm Avenue. Expected to generate 174 PM peak hour trips.
• D & W Development – Day Care facility, vet clinic and medical center located at the northeast corner of
Tahoma Boulevard and Berry Valley Road. Expected to generate 143 PM peak hour trips.
The proposed project is part of the original Ritter Commercial Development. To date the Yelm Medical Plaza and
an Olympia Federal Savings credit union have been built within the development. There are still two small pads
remaining in this development, of which the proposed development will take one and the other was being
proposed as a Jimmy Johns restaurant and commercial space. Among the other three development elements,
the Viewmont Place and Westmont Place portions have had nothing constructed and the D & W Development
has completed the Our Place to Grow childcare facility. The D & W Development also has a proposed
development project, which is discussed in more detail below.
The MDNS identified a series of mitigation measures for the overall development. Each mitigation includes a
transportation facility charge (TFC) and an established trip threshold for requiring its construction.
Transportation Facility Charge
For each of the identified mitigation measures for the overall development, a separate transportation facility
charge was established. These fees are summarized below:
• $137.20 per PM peak hour trip for the Longmire Street/Yelm Avenue traffic signal.
• $322.68 per PM peak hour trip for the realignment of 93rd Avenue/Burnett Road.
• $63.06 per PM peak hour trip for the construction of the Coates Road extension.
As part of the overall development, the proposed commercial project would pay each TFC.
Mitigation Construction Triggers
The first off-site mitigation improvement to be triggered by build out of the overall development was the
installation of a traffic signal at Longmire Street and Yelm Avenue. The MDNS identified that this improvement
would be required to be in place once the development reached 330 total trips. This threshold is evaluated later
in the memo.
Eagle Plaza Binding Site Plan
In 2011, after the MDNS was issued, a Binding Site Plan was adopted for the Ritter Commercial Development. At
this time it was renamed Eagle Plaza and established the property access and building locations. The proposed
commercial development is consistent with the 2011 Binding Site Plan. The Binding Site Plan is attached.
Current Build Out Assessment
The original traffic study for the combined properties suggests that the trip generation for the currently
constructed uses and the proposed uses will fall short of the mitigation trigger for construction of a traffic signal
at Yelm Avenue and Longmire Street. To verify this PM peak period traffic volume counts were collected at each
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of the four driveways serving the Eagle Plaza Development and each of the two driveways serving the Our Place
to Grow childcare facility. The counts were taken on April 18, 2023 between the hours of 4:00 and 6:00 PM and
were collected by Traffic Count Consultants Inc., a traffic data collection firm. The counted totals for each
property are summarized in Table 7. The turning movement count diagrams and turning movement forecasts
are attached.
Table 7. Existing Development Traffic Volumes
Development Enter Exit Total Driveway
Total
Ritter Commercial Development 42 67 109
Our Place to Grow Childcare Facility1 29 30 59
Total Project Trips 71 97 168
1. After a 44% pass-by reduction there would be 33 New-to Network Trips
In total the two development areas generated 168 total driveway trips, which includes pass-by trips that would
not constitute an impact to the surrounding roadway network. As with the proposed uses, the pass-by
percentages contained in the 3rd edition of the Trip Generation Handbook by ITE were reviewed to assess how
much of the observed driveway trips would typically be pass-by trips. There is no identified pass-by rate for
Medical Office, but there is a pass-by rate of 35% for Drive-In Bank and a pass-by rate of 44% for Day Care
Center. The collected driveway counts don’t allow for a distinction between the medical office and drive-in bank
trips so an exact reduction to account for the bank’s pass-by trips is difficult. The Our Place to Grow Childcare
Facility is currently an isolated business so this ITE pass-by rate can be applied to the driveway counts to
determine the new-to-network traffic currently being generated. It should be noted that the counted driveway
volumes will still represent a conservative assessment of the developments impact to the surrounding street
network given the likely pass-by trips associated with the Olympia Federal Savings credit union.
Pipeline Development within the MDNS Properties
In addition to the existing businesses there are multiple proposed developments within the MDNS study area at
different stages:
• Yelm Commercial project, proposing a Jimmy John’s restaurant and 5,200 square feet of commercial
space. This project submitted a traffic memo in April of 2023
• Deutscher Commercial, proposing a 15,000 square foot medical dental office and 15,000 square feet of
commercial space.
Given the additional components to each development area, the overall internal capture potential for each
development has been assessed. These calculations would have been present in the original traffic study and are
based on the based on the methodology contained in the 3rd edition of the Trip Generation Handbook by ITE.
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Eagle Plaza Area
The combination of medical office, bank, restaurant, and commercial/retail space create opportunities for
patrons to perform multiple visits while within the development. These internal trips will reduce the expected
traffic impact to the surrounding street network. An internal trip calculation has been performed using the
observed driveway counts for the existing medical office and bank and the projected site traffic for the Jimmy
Johns and Starbucks developments. A summary of the PM peak hour calculations is provided in Table 8.
Table 8. PM Peak Hour Project Trip Generation
Land Use Size Total Trips Internal
Capture
Pass-By
Trips
New-to-
Network Total Enter Exit
Yelm Medical Plaza & Olympia
Federal Savings Bank NA 109 8 NA 101 38 63
Jimmy Johns 1.2 39 9 17 13 7 6
General Commercial 5.4 50 17 11 22 11 11
Starbucks 2.3 90 20 53 17 8 9
General Commercial 4.0 41 14 11 16 8 8
Total Trips - 329 68 105 169 72 97
The proposed Starbucks project, in conjunction with the proposed Jimmy Johns project, will complete the Eagle
Plaza build out and generate a total new-to-network trip total of 169. This is very similar to the projected 174
trips calculated in the original study.
D & W Development Area
This area was projected to contain a day care facility, vet clinic, and medical center. There is currently a day care
center in the development and the Deutscher Commercial project proposes to construct a medical office
building and commercial space. The initial traffic memo provided to the City of Yelm did not include an
assessment of internal capture between the proposed uses and there is no specific guidance for the internal
capture potential between the proposed uses and a day care facility. While it is likely that some amount of
internal capture is likely between the existing and proposed uses, no calculation is provided at this time. A
summary of the D & W Development PM peak hour trips is provided in Table 9.
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Table 9. PM Peak Hour Project Trip Generation
Land Use Size Total Trips Internal
Capture
Pass-By
Trips
New-to-
Network Total Enter Exit
Our Place to Grow NA 59 NA 26 33 16 17
Medical Office 15.0 59 NA 0 59 18 41
General Commercial 15.0 99 NA 40 59 29 30
Total Trips - 217 NA 66 151 63 88
The proposed Deutscher Commercial project will complete the D & W development area build out, and a total
new-to-network trip total of 151 is very similar to the projected 143 trips calculated in the original study.
Based on the internal capture assessment, a summary of each developments PM Peak Hour new-to-network trip
totals is provided in Table 10.
Table 10. Existing and Proposed Development PM Peak Hour Primary Trip Traffic Volumes
Development Enter Exit Total Driveway
Total
Eagle Plaza Area
Ritter Commercial Development 38 63 101
Jimmy Johns Development 18 17 35
Starbucks Development 16 17 33
Eagle Plaza Total 72 97 169
D & W Development Area
Our Place to Grow Childcare Facility 16 17 33
Deutscher Commercial 47 71 118
D & W Development Total 63 88 151
Total Project Trips 135 185 320
Overall, based on the expected internal capture and pass-by characteristics of the specific uses proposed in the
two development areas, the total net-to-network trips are expected to reach a total of 320 total trips, which will
fall short of the first MDNS mitigation trigger. This aligns with the original study, which identified a total of 317
project trips for these two areas.
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Eagle Plaza Development Driveway Analysis
The previous traffic study included an analysis of the off-site impacts for the combined build out of the four
development areas, which became the basis of the MDNS and the mitigation construction triggers. The
proposed project is beholden to the transportation facility charges and mitigation construction triggers from the
MDNS and as such is not providing any updated analysis of the off-site intersections.
However, development access is more difficult to assess for large studies, as the specific traffic levels and
assignment patterns can change from initial estimates as development occurs. Therefore, to verify that the Eagle
Plaza Development driveways will operate at an acceptable level of service after completion of the proposed
project, each of the existing driveways has been analyzed.
Driveway Operations Analysis
The acknowledged source for determining overall capacity for arterial segments and independent intersections
is the current edition of the Highway Capacity Manual (HCM) published by the Transportation Research Board
(TRB).
Intersection analysis was performed using the Synchro software package. This software implements the
methods of the 6th Edition HCM. Capacity analysis results are described in terms of Level of Service (LOS). LOS is
a qualitative term describing operating conditions a driver will experience while traveling on a street or highway
during a specific time interval. LOS ranges from A (very little delay) to F (long delays and congestion). For
intersections under minor street stop-sign control, the LOS of the most difficult movement (typically the minor
street left turn) represents the intersection level of service. Table 11 shows the Level of Service criteria for stop-
controlled intersections.
Table 11. Level of Service Criteria for Intersections
Level of
Service
Stop-Controlled Intersection Average
Control Delay (seconds/vehicle)
A ≤ 10
B > 10-15
C > 15-25
D > 25-35
E > 35-50
F > 50
Analysis has been conducted for the existing 2023 traffic volumes and projected 2024 volumes with the
proposed project. The operational analysis results of the study intersections for the PM peak hour are provided
in Table 12. The LOS analysis worksheets are attached.
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Table 12. PM Peak Hour Intersection Level of Service
Existing 2023 with
Jimmy Johns 2024 With Project
Intersection LOS (Delay) LOS (Delay)
West Driveway at Yelm Avenue C (19.1) C (24.0)
East Driveway at Yelm Avenue B (13.7) B (14.2)
North Driveway at Tahoma Boulevard B (11.6) B (13.1)
South driveway at Tahoma Boulevard B (11.5) B (12.7)
As shown in Table 12 all of the site driveways are projected to operate at LOS C or better with the proposed
project trips.
Summary
Urban Management Company, LLC is proposing to construct a new 6,300-square foot commercial building in
Yelm, Washington. This project is located at 125 Tahoma Boulevard SE within the Eagle Plaza commercial
development. This project is expected to generate 35 new-to-the network PM peak hour trips without the
completion of the Jimmy Johns project. The 2008 MDNS for this development identified multiple off-site
mitigation triggers. Existing driveway volumes were collected to identify the current traffic generated by the
development areas. Based on those counts and the project trip generation, the project will not trigger any off-
site mitigation improvements. Per the MDNS, the project will pay the identified transportation facility charges,
as follows:
• $137.20 * 35 trips = $4,802.00
• $322.68 * 35 trips = $11,293.80
• $63.06 * 35 trips = $2,207.10
This amounts to a total TFC of $18,302.90.
An operational analysis of the Eagle Plaza Development driveways was performed and each driveway is
projected to operate at LOS C or better with the proposed project trips.
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Thank you for reviewing the enclosed materials. If you have any questions or comments, please contact me or
(360) 352-1465.
Respectfully,
SCJ Alliance
Prepared by Ryan Shea, PTP, Senior Transportation Planner
Approved by Eric Johnston, PE, Principal
Attachments:
Preliminary Site Plan
2008 Mitigated Determination of Nonsignificance
2011 Binding Site Plan
Turning Movement Counts
Traffic Volume Forecasts
Driveway Operational Analysis Worksheets
N:\Projects\3978 Olympia Construction, Inc\22-000832 Yelm Commercial Traffic Engineering Services\04 - Dels\Reports\2023-0427 Yelm Commercial Trip Gen.docx