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TECHNICAL MEMORANDUM
Project: 601 Monster Road SW - Renton
(Tenant Improvement)
Subject: Phase 1 Traffic Assessment
Date: February 16, 2021
Author: Michelle M. Brown, Senior Transportation Engineer
Marni C. Heffron, P.E., P.T.O.E.
The memorandum presents trip generation estimates for the proposed 601 Monster Road SW project in
Renton. The proposed project would make tenant improvements within the existing building footprint.
The building had been assessed as a light industrial use in previous permits and traffic analysis. While the
types of functions accommodated by the tenant improvements would still fit under the light industrial
category, trip generation estimates performed herein account for the tenant’s specific functions, expected
number of employees, and employee shift times. The resulting number of trips were then compared to
what had been previously evaluated for the site. The following sections describe the site and proposed
project, and then present the trip generation methodology and results. An assessment of the City’s traffic
impact fees, and the site’s parking demand are also presented.
1. Site and Project Description
Existing Site and Uses
This project plans to make tenant improvements to an existing 164,480 square foot(sf) building
referenced as 601/701 Monster Road SW. This site was originally assessed as a light industrial use based
on a traffic memorandum prepared in 2017.1 In 2020, a separate applicant sought a tenant improvement
permit to convert the 701 Monster Road SW portion of the building from light industrial use to a food
manufacturing use.2 For both of those prior studies, the 601 Monster Road SW portion of the building
(northern portion of the building) was assumed to remain as a light industrial use with office and
warehouse space.
Proposed Project
The proposed 601 Monster Road SW project would make interior improvements to the northern portion
of the building, which is 91,160 sf. It would reduce the warehouse space from 87,160 sf to 77,740 sf and
increase the internal office space from 4,000 sf to 16,390 sf (including a 2,960-sf mezzanine). The total
occupiable area would increase by 2,960 sf; the exterior footprint would not change. The collective
spaces would be used for logistics storage for computers, office-type equipment, mail and packages, and
provide copy and print services for internal company uses. The southern portion of the building (701
Monster Road SW) is not part of this proposal and will remain unchanged.
1 Traffic Scoping Memo for DCT Industrial at Monster Rd, PRE17-000418, TENW, December 11, 2017.
2 Trip Generation Assessment for Project Tiger (601/701 Monster Rd SW), LUA20-000213 ECF, MOD, TENW, October 8,
2020.
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The space would operate with two employee shifts, and possibly a small third shift, with a total of
between 127 and 149 employees per day. Up to 78 employees are estimated to work the first shift (Day
Shift) with staggered shift start times between 6:00 A.M. and 8:00 A.M. and shift end times between 2:30
P.M. and 5:00 P.M. The second shift (Swing Shift) is estimated to operate with up to 68 employees with
staggered shift start-times between 2:00 P.M. and 5:00 P.M. and shift end-times between 10:30 P.M. and
2:00 A.M. The third shift (Night Shift), if and when needed, would have up to three employees working
during the overnight hours.
Existing parking on the site is assigned by lease, and the 601 Monster Road SW site is allocated 77
vehicle parking stalls and 12 truck parking stalls. The proposed use does not need truck parking, so the
12 truck stalls are planned to be restriped to accommodate 16 vehicle parking stalls. Overall, the project
would have 93 passenger vehicle parking stalls. The site plan is shown on Figure 1.
Figure 1. Site Plan
Source: Nelson, February 2021.
N
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2. Trip Generation
Trip estimates for the project were determined using the high end of the employee counts and shift data
information refenced above. This employee and shift information provided by the applicant were summa-
rized to determine the estimated number of employees that could travel to and from the site every 30
minutes throughout the day. Not all employees would drive alone to the site. To account for employees
who may take transit, walk, bike or carpool to the site, commute data from the Puget Sound Regional
Council (PSRC)3 were used. The PSRC data found that employees in the site vicinity 4 made about 93% of
their trips by vehicle (either a single-occupant trip or a carpool). About 3% of the trips were made by
transit trips and 5% walk/bike or use other modes. The 93% vehicle-use was applied to the employee
counts to estimate the number of vehicle trips to and from the site. Employee vehicle trips by 30-minute
period are shown on Figure 2.
Figure 2. Employee Vehicle Trips by 30-minute Period
Source: Heffron Transportation, Inc., February 2021. Based on estimated employees by shift provided by The Seneca Group.
As shown on the above figure, employee shifts would be staggered with arrivals and departures spread out
over the day, including during the peak commute times. Per the City of Renton Traffic Impact Analysis
Policy Guidelines for New Development,5 a project’s peak hour traffic is defined as the peak volumes for
one hour between 6:00 and 9:00 A.M. and between 3:00 and 6:00 P.M. Within those windows, the morning
peak hour would occur between 6:30 and 7:30 A.M. and the afternoon peak hour would occur between 3:30
and 4:30 P.M. The peak hour trip generation estimates (38 AM peak hour trips and 38 PM peak hour trips)
are shown below in Table 1. The project is estimated to generate 400 daily trips, which includes the
employee, visitor, and delivery trips. Based site operations information, about 20 to 40 delivery trips are
3 PSRC, Journey-to-Work data compiled from the US Census Bureau, 2006-2010 American Community Survey Estimates,
January 31, 2014.
4 Transportation analysis zones around site Zone 339 (no data): 324 336, 337, 338, and 341.
5 City of Renton Traffic Impact Analysis Policy Guidelines for New Development, January 2016.
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estimated each day. These deliveries would account for between 5 and 10% of the daily trips, and would
likely be scheduled to occur outside the employee peak arrival and departing times. Deliveries are likely to
occur using small trucks and/or parcel delivery vans.
A prior assessment of the 601 Monster Road SW site was completed in 2017 as part of the entire site
evaluation. The estimated number of peak hour trips, based on the square footage for the 601 Monster
Road SW portion of the building. is also summarized below in Table 1. The calculated net change between
the proposed uses based on employee and shift information, and the prior assessment are provided. The
proposed use is estimated to generate a net decrease of 15 daily trips, 5 fewer AM peak hour trips, and 3
additional PM peak hour trips.
Table 1. Vehicle Trips Generated by 601 Monster Road SW
Daily AM Peak Hour 1 PM Peak Hour 2
Condition Trips In Out Total In Out Total
Proposed
Warehouse/Office 3 400 35 3 38 3 35 38
Prior Assessment
Light Industrial 4 415 38 5 43 5 30 35
Net Change -15 -3 -2 -5 -2 5 3
1. AM Peak Hour = 6:30 -7:30 A.M. based on facility operations.
2. PM Peak Hour = 3:30 - 4:30 P.M. based on facility operations.
3. Peak hour trip estimates based on 149 employees, shift information provided by applicant in January 2021, and vehicle mode split
data from 2010 Census data by Puget Sound Regional Council. Daily trip estimates based on employee, visitor, and delivery
information.
4. Trip estimates from Traffic Scoping Memo for DCT Industrial at Monster Rd, PRE17-000418, TENW, December 11, 2017l, based on
ITE Trip Generation Manual, 10th Edition, September 2017, for LUC 110 - Light Industrial use for 96,236 sf.
3. Traffic Impact Analysis
The City of Renton requires a traffic impact analysis be completed when estimated vehicular traffic
generated from a proposed development exceeds 20 vehicles per hour in either the AM peak hour or PM
peak hour.6 The estimated net change in trip generation for the proposed project is below 20 vehicles during
both peak hours; therefore, no additional traffic analysis would be required based on the City’s guidelines.
4. Transportation Impact Fees
The City of Renton collects traffic impact fees. The 2021-2022 7 fee schedule lists light industrial as the
closest category to match the proposed site with a fee of $9.50 per square foot. Since the internal usable
square footage would increase by 2,960 sf, the estimated transportation impact fee would be $28,120.
6 City of Renton Traffic Impact Analysis Policy Guidelines for New Development, January 2016.
7 City of Renton website accessed February 2021.
https://edocs.rentonwa.gov/Documents/DocView.aspx?id=8373700&dbid=0&repo=CityofRenton&cr=1
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5. Parking Supply and Demand
The proposed project would retain the existing 77 vehicle parking spaces and restripe the existing
truck/trailer spaces to provide a total of 93 vehicle parking spaces for the project.
At full capacity with the assumed day, swing, and night shifts, the peak parking demand is estimated at
93 vehicles. This demand is expected to occur for short periods of time during the overlap between the
day and swing shifts when employees who arrive in the afternoon are on site before the day shift
employees have left the site. The proposed on-site parking supply would accommodate this peak.
MCH/mmb
601 Monster Rd Renton Traffic Assessment Final 2-2021.docx