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6544 NE 61st Street Seattle, WA 98115 206-523-3939 hefftrans.com
MEMORANDUM
Date: November 18, 2025
Project: Virginia Mason Athletic Center (VMAC) Expansion
12 Seahawks Way, Renton, WA
Subject: Parking and Traffic Analysis
Authors: Marni C. Heffron, P.E., P.T.O.E., Principal Transport Engineer
Cole Laush, Transportation Planner
This memorandum presents detailed parking and traffic analysis for the Virginia Mason Athletic Center
(VMAC) in Renton, WA. This facility, owned and operated by the Seattle Seahawks, is one-of-a-kind.
Therefore, its trip generation and parking demand were determined using counts and surveys of the existing
site. These data were then used to estimate how the proposed expansion would increase the site’s trips and
parking demand. The net increases in trips were then assigned to the roadway network to assess how they
would affect traffic operations in the site vicinity, and for the City’s use in assessing Transportation
Concurrency and the traffic impact fee. The methodology and findings are presented herein.
1. Project Description
1.1. Existing Site and Facilities
Figure 1 shows the existing VMAC site and facilities. Existing buildings on the VMAC site include the
251,800-square foot (sf) main building and a 5,000-sf maintenance shed. The main building has an
88,600-sf indoor practice facility with the remaining space for team support and administration.
The site’s main parking lot (North Lot) is located on the north end of the site, wrapping around the main
building’s northwest, north, and east sides. There are 248 marked parking stalls in the North Lot;
however, the Seahawks utilize valets to stack-park some of the parking aisles. The North Lot has two
driveways connecting to Seahawks Way, but the southernmost of those driveways is gated and typically
not open for vehicular access (except for deliveries and events). The practice field maintenance building,
which has five (5) parking stalls, is accessed via a driveway south of the field. That driveway crosses
property not owned by the Seahawks including a gravel parking area with capacity for about 45 vehicles
that is leased by the Seahawks. The maintenance building parking and off-site parking are collectively
referred to herein as the South Lot.
1.2. Proposed Expansion
The proposed expansion project would have several components. A new three-story building with about
51,000 sf of space is proposed to the east of the existing building, the footprint of which would eliminate
some parking in the North Lot. Another component on the west side would expand Level 3 of the main
building with approximately 21,600 sf of new space. Figure 2 shows the expansion concept plans.
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Figure 1. VMAC Existing Layout and Facilities
Source: Google Earth, image from 7/5/2024.
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Figure 2. VMAC Expansion Concept Plan
Source: HOK, November 2025.
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Table 1 summarizes the key site metrics that will be used for the traffic and parking analysis.
Table 1. VMAC – Existing and Proposed Program
Buildings Existing a
Net Change
with Expansion a Total
with Expansion a
Main Building
Indoor Practice Facility 88,600 sf No change 88,600 sf
Support and Administration 163,200 sf +72,600 sf b 235,800 sf
Total 251,800 sf +72,600 sf 324,400 sf
Maintenance Shed 5,000 sf No change 5,000 sf
Total Buildings 256,800 sf +72,600 sf 329,400 sf
a. HOK, Expansion Study site areas, May 28, 2025
b. Assumes 51,000 sf in East Expansion plus 21,600 sf for West Infill.
2. Parking Demand
Parking analysis was performed to assist the Seahawks and City with determining the appropriate level of
parking needed to accommodate the VMAC’s needs.
2.1. Parking Study Methodology
A detailed parking occupancy and accumulation study was performed at the VMAC in fall 2025 to
determine how parking is currently utilized. The following data were collected for the parking study.
• Three-day (72-hour) machine traffic counts. These counts were performed at the site’s north
driveway, which provides access to the main parking lot, as well as the south driveway to the
leased off-site parking lot and field maintenance building. The counts were performed using
pneumatic tubes during the period from Tuesday, September 30 through Thursday, October 2,
2025. The data were compiled by 15-minute intervals over the three-day period (Tuesday,
Wednesday, and Thursday) to show how parking accumulated and dissipated throughout the
course of the survey days. The survey dates reflect a mid-week condition in advance of a
Seahawks home game against the Tampa Bay Buccaneers on Sunday, October 5, 2025.
• Peak period video counts at the site driveways. Companion counts were performed at both
driveways on Wednesday, October 1, 2025. These counts were used to validate the pneumatic
tube counts and capture turning movements by direction.
• Manual parking occupancy counts. Manual counts of parked vehicles were performed on
Wednesday, October 1, 2025 between 10:30 A.M. and 3:00 P.M. to provide a benchmark for
midday parking occupancy and to observe parking operations.
2.2. Existing Parking Demand
Parking occupancy at the VMAC was derived from the driveway counts. These data provide parking
accumulation for every 15-minute period over a three-day period, and include both the on-site and the
leased off-site parking lots. Figure 3 shows the parking accumulation. The peak demand occurred during
the lunch hour on Wednesday when 335 vehicles were parked: 290 in the North Lot and 44 in the South
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Lot. The Seattle Seahawks utilize valets to stack-park sections of the North Lot. Based on the parking
accumulation data, the valet operation increased parking capacity by 42 vehicles.
Figure 3. Parking Occupancy at VMAC
Source: Heffron Transportation, Inc. based on manual parking counts at site and three-day counts at two driveways, performed from
September 30 through October 2, 2025.
Additional analysis was performed for the peak day during the survey (Wednesday, October 1, 2025).
Figure 4 shows how vehicles arrived and departed the site each 15-minutes and how parking demand
changed over the course of that day. This shows that parking demand is highest from about 10:00 A.M. to
about 3:00 P.M. with a peak occurring over the lunch hour. The chart also shows that trip patterns
generated by the facility are similar to traditional employee commute patterns with the majority of
vehicles arriving over the course of the morning hours and departing during the late afternoon and early
evening hours. However, the VMAC has longer commute periods than a traditional office worksite, and
peak vehicle flows are spread out over more time.
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Figure 4. VMAC Peak Day Vehicle Accumulation – Wednesday, October 1, 2025
Source: Heffron Transportation, Inc. based on manual parking counts at site and 72-hour counts at two driveways. Chart reflects the peak day
of the three days counted from Tuesday, September 30, 2025 through Thursday, October 2, 2025.
2.3. Peak Parking Demand Rate
Parking demand rates were derived based on three metrics: 1) the entire size of the existing VMAC facility,
2) just the size of the administrative building space (which excludes the floor area of the indoor practice
facility and maintenance shed), and 3) the existing number of staff (including players). For metric number
2, the calculation assumes that the indoor practice facility and maintenance shed are accessory uses to the
main administrative space.
Table 2. Peak Parking Demand Rates - VMAC
Basis for Rate Peak Parking Demand a Size Parking Demand Rate
Total Size of All Facilities 335 vehicles 256,800 sf 1.30 veh / 1,000 sf
Size of Just Administrative Space 335 vehicles 163,200 sf 2.05 veh / 1,000 sf
Total Employment 335 vehicles 344 employees b 0.97 veh / employee
a. Based on the peak demand observed over the course of three days from September 30 through October 2, 2025.
b. Seattle Seahawks, October 2025. Value includes an estimated 70 active and practice squad football players.
The rates were compared to various rates in the Institute of Transportation Engineers’ (ITE) Parking
Generation Manual,1 which is the typical source used to derive parking demand. The rate of 2.05 vehicles
per 1,000 sf of administrative space is similar to ITE’s rate for a General Office Building (1.95 vehicles
per 1,000 sf). The rate per employee of 0.97 vehicles per employee is higher than ITE’s employee rate for
an office use (0.79 vehicles per employee). It is acknowledged that the VMAC has many spaces that
would not be found in a traditional office building, such as weight and training rooms, and the proposed
1 ITE, Parking Generation Manual, 6th Edition, October 2023.
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Total Parking Demand
Peak Parking Demand = 335 Vehicles
Peak Parking in North Lot = 290 Vehicles
Peak Parking in South Lot (Off-Site) & Maintenance Lot =
45 Vehicles
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expansion of administrative space will not be accompanied by a proportional increase in staffing.
Therefore, as described below, the rates based on the full facility size and employment would likely
reflect the most accurate estimates for future parking demand.
2.4. Estimated Future Parking Demand with Expansion
Future parking demand was estimated using three different methods. The first method aligns with the
typical approach that the City of Renton might apply to determine the code-required supply. This method,
presented in Table 3, applies a parking demand rate to the individual land uses within the facility. If the
City’s parking demand for office use is applied to the administrative space, the parking supply requirement
for the existing VMAC facility would equate to 327 stalls. Under that condition, the indoor practice facility
and the maintenance shed would be considered accessory uses that require no additional parking. If that
same paradigm is extended to the future condition, the project would require 472 parking stalls.
Table 3. Existing and Future Parking Requirement – Using City of Renton Code Rates
Existing Condition Proposed
Land Use Parking Rate Size Parking Required Size Parking Required
Office / Administration 2 per 1,000 sf 163,200 sf 327 stalls 235,800 sf 472 stalls
Indoor Practice Facility None
(Accessory Use) 88,600 sf 0 stalls 88,600 sf 0 stalls
Maintenance Shed None
(Accessory Use) 5,000 sf 0 stalls 5,000 sf 0 stalls
Total 256,800 sf 327 stalls 329,400 sf 472 stalls
Source: Heffron Transportation, Inc., October 2025.
The above method does not account for the fact that large areas of the VMAC office / administration
space are used for atypical functions, such as large weight training and treatment rooms. These functions
do not support additional employee density or induce related parking demand. As a result, the City’s
parking code rate for Office / Administration uses reflects an unreasonably high parking requirement.
To account for the unique VMAC operations, the parking rates derived in Section 2.3 were applied to
both the facility’s gross square footage and employee levels. Table 4 summarizes the parking need based
on these rates. As shown, application of these metrics results in an estimated parking need of 428 to 435
stalls. Therefore, 435 parking stalls are recommended for the future VMAC with the expansion.
Table 4. Existing and Future Parking Need – Using Facility-Specific Parking Rates
Existing Condition Proposed
Analysis Metric Parking Rate a Size Parking Need Size Parking Need
Facility Size 1.30 per 1,000 sf 256,800 sf 335 stalls 329,400 sf 428 stalls
# of Employees 0.97 per emp 344 employees 335 stalls 447 employees 435 stalls
Source: Heffron Transportation, Inc., October 2025.
a. Rates derived from site-specific parking study, and presented in Table 2 above.
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2.5. Parking Management Recommendations
The parking demand analysis determined that the VMAC should provide parking for 435 vehicles. The
following measures are recommended to achieve this parking need:
• Increase on-site parking through the use of valets. The Seahawks currently use valets and
stack parking to increase the capacity of the North Lot. It is estimated that valets could fit an
additional 30 vehicles in this lot, which would compensate for the parking lost due to the building
expansion.
• Provide up to an additional 95 parking stalls in off-site locations. The Seahawks should work
with the City of Renton and Washington State Department of Transportation (WSDOT) to
determine if off-site parking could be created in areas now being used for Interstate 405 (I-405)
construction staging. If not feasible, alternative off-site parking should be procured. If parking is
further than ½-mile from the site, the off-site parking should be paired with a shuttle service.
Table 5 summarizes the recommended parking supply paradigm.
Table 5. Existing and Future Parking Supply
Parking Location Existing
Net Change
with Expansion
Total
with Expansion
On-Site Parking
North Lot 248 stalls -30 stalls 218 stalls
Valet Stack Parking 42 vehicles + 30 vehicles 72 vehicles
Maintenance Bldg. 5 stalls -- 5 stalls
Off-Site Parking
South of Practice Field 45 stalls -- 45 stalls
Other Off-Site -- Up to 95 stalls 95 stalls
Total Parking 340 vehicles Up to 95 vehicles 435 vehicles
Source: Heffron Transportation, Inc., October 2025.
• Reduce parking demand through travel demand management (TDM) programs. The
number of off-site parking stalls needed could be reduced by implementing TDM programs that
reduce vehicular travel. Potential programs could include:
o Increase carpool use – Encourage employees to carpool to the VMAC by implementing
carpool matching programs, and incentives such as priority parking in convenient spaces.
o Increase transit use – A new bus rapid transit (BRT) station is being constructed at the
I-405/NE 44th Street interchange, which would be less than one-third mile from the south
end of the VMAC practice field. Sound Transit’s Stride S1 line will operate along I-405
connecting downtown Bellevue and the Tukwila International Boulevard Station.
Employees should be encouraged to use this new service.
o Encourage non-motorized travel – The adjacent Lake Washington Trail is planned to
connect to the Eastrail Trail that will connect to Bellevue, Kirkland, Woodinville,
Redmond, and beyond. The VMAC already has lockers and showers to support employee
bike commutes.
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Every employee who carpools, takes transit, or bikes to work would reduce the number of parking stalls
required by one space. Because there is no other near-site or on-street parking that VMAC employees
could use, it is expected that the Seahawks will implement a package of parking improvements that meets
its employee’s needs. Therefore, the VMAC expansion would not create any adverse parking impacts.
3. VMAC Trips
3.1. Existing VMAC Trips
Daily and peak hour site trip generation estimates were derived from the driveway counts described
previously. The peak hour trips reflect the highest volumes that occur during the traditional morning
(AM) and afternoon/evening (PM) commuter peak periods. The AM peak hour on all three days
consistently occurred from 8:00 to 9:00 A.M.; the PM peak hour occurred from 4:45 to 5:45 P.M. on two
days and from 5:00 to 6:00 P.M. on Thursday. Table 6 summarizes the trip generation for each of the three
days surveyed. The average trip generation was determined to be 926 vehicle trips per day with 121 trips
during the AM peak hour and 125 trips during the PM peak hour.
Table 6. VMAC – Existing Trip Generation
Daily Vehicle Trips AM Peak Hour Trips PM Peak Hour Trips
Count Day In Out Total In Out Total In Out Total
VMAC North Driveway
Tues 9/30/2025 394 394 788 62 7 70 30 59 89
Wed 10/01/2025 408 408 816 76 6 82 12 98 110
Thurs 10/2/2025 409 409 818 66 4 70 22 79 101
Average of 3 Days 404 404 808 68 6 74 21 79 100
VMAC South Lot Driveway
Tues 9/30/2025 56 56 112 40 7 47 2 24 26
Wed 10/01/2025 63 63 126 43 2 45 2 23 25
Thurs 10/2/2025 59 59 118 43 6 49 1 23 23
Average of 3 Days 59 59 118 42 5 47 2 23 25
Total For Both Driveways 463 463 926 110 11 121 23 102 125
Source: Based on three-day machine counts performed at both site driveways by IDAX Data Solutions, Sept. 30 through Oct. 2, 2025.
3.2. Trip Generation Rates
Trip generation rates were derived from the total site trips based on both the existing facility size and
number of employees. Table 7 summarizes the facility-specific rates. It also presents rates listed in ITE’s
Trip Generation Manual 2 for General Office use. This comparison shows that the VMAC facility does not
function like a typical office facility, having rates that are far below those in the ITE manual. The peak
hour VMAC-specific trip rates based on square footage are about 60% lower than those in the ITE manual,
while those based on employees are about 30% lower. This further confirms that much of the space in the
facility is accessory to the administrative functions and does not generate additional site trips. Based on
this analysis, it is recommended that the VMAC-specific trip rates be used to estimate future trips.
2 ITE, Trip Generation Manual, 12th Edition, August 2025.
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Table 7. VMAC Trip Generation Rates vs ITE Rates
VMAC -specific Trip Generation Rates a ITE Trip Generation Rates for Office Use b
Time Period Trip Rate based on Facility Size Trip Rate based on Employee Trip Rate based on Facility Size Trip Rate based on Employee
Daily 3.61 trips / 1000 sf 2.69 trips / employee 7.83 trips / 1000 sf 3.44 trips / employee
AM Peak Hour 0.47 trips / 1000 sf 0.35 trips / employee 1.24 trips / 1000 sf 0.49 trips / employee
PM Peak Hour 0.49 trips / 1000 sf 0.36 trips / employee 1.18 trips / 1000 sf 0.45 trips / employee
a. Based on three-day machine counts performed at both site driveways by IDAX Data Solutions, Sept. 30-Oct 2, 2025. The rates were
derived based on the total size of the facility (which is 256,800 sf) or the number of employees, which is currently estimated at 344.
b. Rates from the Institute of Transportation Engineers, Trip Generation Manual, 12th Edition, August 2025. Rates for General Office Building
(Land Use Code 710, in General Urban/Suburban setting).
3.3. Future VMAC Trips
The trip generation rates derived for VMAC were applied to estimate trips associated with the proposed
expansion Table 8 shows that the future trip estimates based on square footage and employees are nearly
identical. The higher of these two estimates will be used to determine the net change in site trips for each
driveway.
Table 8. VMAC – Future Trip Generation
Daily Vehicle Trips AM Peak Hour Trips PM Peak Hour Trips
Basis for Trip Generation Size In Out Total In Out Total In Out Total
Based on Facility Size 329,400 sf 595 595 1,190 141 14 155 29 131 160
Based on Employees 447 employees 600 600 1,200 143 14 157 30 132 162
Source: Heffron Transportation, Inc., October 2025. Rates derived from site-specific parking study, and presented in Table 7 above.
3.4. Net Change in VMAC Trips
Trip generation estimates for the VMAC with the proposed expansion were developed using the employee-
based rates presented in the prior section. Table 9 presents the results as well as the trip generation for the
existing site. As shown, with the proposed expansion, the VMAC is expected to generate about 274 more
vehicle trips per day than the existing facility. The project would generate a new increase of 36 trips during
the AM peak hour and 37 trips during the PM peak hour. Although the expansion would eliminate some
parking in the North Lot, the valet operation is expected to be able to park the same number of vehicles on
the site as currently accommodated (290 vehicles). Therefore, no additional trips would occur at the North
Driveway. A small increase in trips is expected at the South Lot driveway since that lot has some
additional capacity based on the parking analysis. The remaining trips would all occur at the off-site
parking lot, which is expected to have a minimum of 95 parking spaces. The off-site lot is expected to
generate 260 trips per day with 31 trips in the AM peak hour and 34 trips in the PM peak hour.
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Table 9. Net Change in Trips by Location
Number of
Parked Vehicle
Daily
Trips
AM Peak Hour Trips PM Peak Hour Trips
Count Day In Out Total In Out Total
VMAC North Driveway
Existing 290 808 68 6 74 21 79 100
Future with Expansion 290 808 68 6 74 21 79 100
Net Change due to Project 0 0 0 0 0 0 0
VMAC South Lot Driveway
Existing 45 118 42 5 47 2 23 25
Future with Expansion 50 132 47 6 52 2 26 28
Net Change due to Project 14 5 1 5 0 3 3
New Off-Site Parking
Existing 0 0 0 0 0 0 0 0
Future with Expansion 95 260 28 2 31 7 27 34
Net Change due to Project 260 28 2 31 7 27 34
Total All Locations
Existing 335 926 110 11 121 23 102 125
Future with Expansion 435 1,200 143 14 157 30 132 162
Net Change due to Project 274 33 3 36 7 30 37
Source: Heffron Transportation, Inc., October 2025.
3.5. Trip Distribution Patterns and Assignments
Project trips were assigned to the roadway network based on expected travel patterns once the I-405
interchange at NE 44th Street is reconstructed (see Section 4.2). The general trip patterns assume that 85%
of the VMAC traffic would use I-405 (35% to and from the north and 50% to and from the south), with
10% to and from residential areas east of I-405 (Newcastle) and 5% to and from Lake Washington
Boulevard west of I-405. The new interchange will have direct high-occupancy-vehicle (HOV) access
ramps in the center of I-405. It was assumed that 5% of the trips to and from I-405 could use these ramps.
The trip patterns reflect the future paradigm where Seahawks Way traffic will be restricted to right-turn-
only movements at the NE 44th Street intersection, and vehicles would need to travel to the adjacent
intersections where roundabouts are planned in order to make a U-turn to reach their destination. Figure 5
shows the net changes in AM and PM peak hour VMAC trips on area roads.
VMAC
Future Roundabout
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AM Peak Hour (PM Peak Hour) Traffic Volume
Trip Distribution Pattern
Future Bus Rapid Transit (BRT) Station
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Figure 5
Net Change in VMAC Trips
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VMAC EXPANSION
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4. Traffic Analysis
The City of Renton’s Policy Guidelines for Traffic Impact Analysis for New Development 3 states, “A
traffic impact analysis is required when estimated vehicular traffic generated from a proposed
development exceeds 20 vehicles per hour in either the AM (6:00 to 9:00) or PM (3:00 to 6:00) peak
periods.” The project’s net increase in trip generation (see Table 9) would exceed this threshold.
Additional analysis presented in this section includes a description of the planned roadway system,
assessment of local traffic operations, and traffic impact fee estimate.
4.1. Planned Roadway System
The VMAC is accessed from Seahawks Way, a dead-end street that only connects to NE 44th Street south
of the site. There are no other public streets in the narrow strip of land between I-405 and Lake
Washington.
I-405 and the interchange at NE 44th Street are currently being reconstructed by WSDOT as part of the I-
405/Renton to Bellevue Widening and Express Toll Lanes Project. In general, WSDOT’s Renton-to-
Bellevue project will add one lane to I-405 in each direction for about nine miles beginning near State
Route (SR) 167 and continuing approximately one mile north of Interstate 90 (I-90). The project will also
add a general-purpose (auxiliary) lane to southbound I-405 between milepost (MP) 6.7 (north of N 30th
Street) and MP 7.1 (south of NE 44th Street) and from MP 9.4 (north of 112th Avenue SE) to MP 10.5
(north of Coal Creek Parkway). The existing HOV lane on I-405 and the additional auxiliary lane will be
operated as a two-lane express toll lane system.
WSDOT is also rebuilding the I-405 / NE 44th Street interchange. NE 44th Street formerly crossed I-405
on a bridge and standard diamond-ramp intersections were controlled by stop signs. When complete, the
new interchange, with NE 44th Street aligned below I-405, will have new ramps plus center-connecting
HOV-only ramps and a Bus Rapid Transit (BRT) station accessed from those HOV ramps. All ramps and
new intersections along NE 44th Street will be controlled by roundabouts. Figure 6 shows WSDOT’s
conceptual plan of the interchange improvements.
3 City of Renton Permit Services, February 24, 2023.
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Figure 6. Planned I-405 / NE 44th Street Interchange Improvements
Source: WSDOT and Flatiron-Lane, Conceptual Design, Forward Compatibility Plans, Received from I-405 Construction Outreach Team,
November 12, 2025.
With the new construction, Seahawks Way is planned to be controlled by a stop sign where it intersects
NE 44th Street and restricted to right-turns in / right-turns out. Another roundabout is proposed to the
southwest of Seahawks Way—at NE 43rd Street/Lake Washington Boulevard—where traffic from
Seahawks Way can U-turn in order to reach the NE 44th Street interchange ramps.
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4.2. Traffic Volumes for NE 44th Street Interchange Area
WSDOT, through its consultant HNTB, performed extensive analysis of the improvements now under
construction at the NE 44th Street interchange. It evaluated future conditions without and with the im-
provements for the years 2025 and 2045.
The full corridor growth assumptions were provided in the Transportation Discipline Report: I-405,
Tukwila to I-90 Vicinity Express Toll Lanes Project (MP 0.0 to 11.9) and Downtown Bellevue Vicinity
Express Toll Lanes Project (MP 11.9 to 14.6).4 Additional detail was provided in the companion I-405
Renton to Bellevue – NE 44th Street Intersection Control Analysis Report.5 According to WSDOT,6 its
2025 traffic volume forecasts assumed traffic generated by three major developments plus background
growth. The three developments were:
• The Port Quendall Terminals development located on the north side of Lake Washington Boulevard
N between N 43rd Street and Seahawks Way;
• The Hawk’s Landing development located on the south side of Lake Washington Boulevard N
between the southbound I-405 on-ramp and N 43rd Street; and
• The Kennydale Mixed-Use development located on the south and east side of Lake Washington
Boulevard N.
The 2045 forecasts reflected about 2.3% more traffic on NE 44th Street at Seahawks Way.
4.3. Traffic Operations Analysis
WSDOT’s Transportation Discipline Report also assessed levels of service (LOS) for intersections at and
near the NE 44th Street interchange, which were determined using SIDRA software (used to evaluate
roundabouts) and Synchro software (used to evaluate the intersection at Lake Washington Boulevard N /
Seahawks Way).7
Level of service is a measure of congestion, with LOS A reflecting good operations with little to no
congestion and LOS F, reflecting poor operations with substantial congestion. While WSDOT had no
targeted level of service standard for the I-405 corridor improvements, the WSDOT Level of Service
Standard Map 8 indicates LOS D is the standard for I-405. WSDOT’s analysis found that all of the
proposed roundabouts are expected to operate at good levels of service (LOS B or better) in the year 2045
with the proposed interchange configuration during both the AM and PM peak hours.
Seahawks Way is assumed to be restricted to right-turn-in/right-turn-out only. Traffic destined to the I-
405 interchange would need to turn right and then U-turn at the proposed roundabout at the Lake
Washington Boulevard/NE 43rd Street intersection. Heffron Transportation, Inc. used the WSDOT models
for this intersection to assess operations with the proposed VMAC expansion. Based on this analysis, the
right turn movement from Seahawks Way onto NE 44th Street is expected to operate at LOS C in 2045
with the proposed VMAC expansion.
The analysis shows that all intersections being reconstructed at this interchange would operate at
acceptable levels of service in the long-term future (year 2045). The proposed VMAC expansion would
not adversely affect operations.
4 WSDOT, July 2018.
5 WSDOT, July 2018.
6 E-mail from Sean Quarrie of WSDOT to Marni Heffron, Heffron Transportation, March 8, 2019.
7 WSDOT/HNTB Sidra and Synchro models for year 2025 build (with interchange improvement) conditions.
8 WSDOT Level of Service Map,
https://wsdot.maps.arcgis.com/home/item.html?id=3f840aeeb1ba481c905270ca103cd1db#!, accessed July 25, 2022.
Virginia Mason Athletic Center (VMAC) Expansion
Parking and Traffic Analysis
November 18, 2025 | 16
4.4. Traffic Impact Fee
The City of Renton will assess a Transportation Impact Fee for the proposed VMAC expansion. The City
of Renton Fee Schedule for 2025-2026 lists rates by general land use category tied to standard trip rates in
ITE’s Trip Generation Manual, and also lists a rate based on the “Net New PM Peak Hour Person
Vehicle Trips.” As described previously, the VMAC is a unique use not represented by the available ITE
land use categories; therefore, trip generation was derived from counts at the VMAC site driveways (see
Section 3.4). The analysis determined that the VMAC expansion would generate a net increase of 37
vehicle trips during the PM peak hour.
Based on the methodology presented in Appendix A of the City’s Rate Study for Impact Fees for
Transportation,9 trip rates are multiplied by an average vehicle occupancy (AVO) rate, divided by a
motorized mode share rate, and multiplied by a new-trip percentage. Given that there is no transit service
proximate to the site and no carpool programs, the AVO is assumed to be 1.0 with 100% motorized trips.
All trips are also assumed to be new (no pass-by trips). Therefore, the number of new vehicle trips is also
assumed to reflect the net increase in person trips. When applied to the City’s Traffic Impact Fee Rate of
$8,031.94 per net new person-vehicle trip, the Traffic Impact Fee would be $297,181.78. It is noted that
the fee will be determined at the time of building permit based on the fee rate in effect at that time.
5. Summary
The VMAC is a unique land use; therefore, its parking and trip generation were derived from data
collected at the site. The proposed expansion of the building would eliminate about 30 on-site parking
stalls, and that loss could be mitigated through increased use of valet stack parking in the North Lot. Up
to 95 additional off-site parking spaces would be needed to serve the increased demand generated by the
expansion. The number of off-site parking stalls needed could be reduced through TDM programs that
increase carpooling, transit use, and bicycle commuting. The Seahawks should work with the City of
Renton and WSDOT to determine if parking can be created in areas now being used for I-405
construction staging. If not, off-site parking would likely need to be served by a shuttle between an
alternative off-site lot and the VMAC.
The proposed expansion would increase vehicle trips by 274 per day, 36 during the AM peak hour, and 37
during the PM peak hour. The project would not adversely affect traffic operations in the site vicinity
since the nearby NE 44th Street / I-405 interchange is currently being reconstructed with all new
roundabout-controlled intersections. Seahawks Way, which will be restricted to right-turn in/right-turn
out only, is expected to operate at LOS C in 2045 with the proposed VMAC expansion.
The Traffic Impact Fee was estimated using the City’s rate of $8,031.94 per PM peak hour person-vehicle
trip. The fee for the net increase of 37 trips is estimated to be $297,181.78.
MCH/tsm
VMAC Expansion - Parking and Traffic Analysis -FINAL - 11-18-2025.docx
9 Henderson Young & Company, July 5, 2016.