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TECHNICAL MEMORANDUM
Project: Renton School District’s Lindbergh High School Renovation
Subject: Transportation Analysis
Date: January 17, 2022
Author: Tod S. McBryan, P.E.
This memorandum summarized the transportation and parking analyses for the proposed renovation of
Lindbergh High School. This analysis follows the City of Renton’s Traffic Impact Analysis Policy
Guidelines for New Development.1 Please contact Tod McBryan at (206) 527-8410 with any questions
regarding this memorandum.
1. Project Description
1.1. Site Description
The Renton School District (RSD) is proposing to renovate the existing Lindbergh High School, which is
located at 16426-28th Avenue SE in Renton. The school site is comprised of three parcels that total over 37
acres in size and are bounded by 128th Avenue SE on the west, single-family residential parcels on the
north and east, and by vacant and institutional (church and elementary school) parcels to the south. Figure 1
shows the site location and vicinity.
1.2. Project Proposal
The proposed project would construct additions and remodel the interiors of various spaces within the
existing school. The work would be completed in phases with the school occupied for the duration of
construction. The following lists the key project components.
An addition (of about 1,950 square feet (sf)) is proposed at the school’s main entrance and
intended to house the administration and health suite. The existing lobby and commons spaces
would be renovated to accommodate the new administration location.
Demolition of 6,295-sf and addition of 9,735-sf (net building increase of 3,440 sf) on the
northeast portion of the school to house four science classrooms and support spaces.
The existing science wing would be renovated to modernize existing science classrooms and
support spaces. A small (700 sf) mechanical addition is proposed on the east side of the existing
science classroom wing to serve the renovated classrooms. The existing restrooms at the science
wing will also be modernized with fixture replacements and minor interior adjustments to the
partition and fixture locations so that the restrooms will meet accessibility requirements.
The project would modernize the existing locker rooms at the gymnasium resulting in equally
sized girls’ and boys’ locker rooms with showering and changing facilities. A classroom, training
room, and storage rooms would also be provided.
1 City of Renton, 2020.
Renton School District’s Lindbergh High School Renovation
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Figure 1. Site Location and Vicinity
Source: Google Earth, October 2021. Annotations by Heffron Transportation, Inc.
Interior renovations are planned to support the relocation of various program areas, including
work to partially demolished and reconfigure the existing administration office to house the
counseling office and career center.
HVAC system upgrades are proposed throughout the existing building and gymnasium.
Site work would relocate underground utilities at the main entrance of the building. Clearing,
grading, and general site preparation would be needed for the mechanical addition at the east side
of the existing science wing. Finally, the existing southwest parking lot would be repaired and
resurfaced.
Figure 2 shows the site plan. Construction is planned to begin in 2022 and be complete in 2024.
Source: BassettiArchitects, January 12, 2022
Figure 2
Proposed Site Plan
Renton School District
Lindbergh High School Renovation
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Renton School District’s Lindbergh High School Renovation
Transportation Analysis
January 17, 2022 | 4
2. School Trip Generation
As outlined in City’s Traffic Impact Analysis Policy Guidelines for New Development, the City requires
trip generation estimates for development projects be derived using rates and equations in the most
current edition of the Institute of Transportation Engineers’ [ITE] Trip Generation Manual.2 For High
Schools (Land Use Code 525), the current edition provides rates and equations based on either number of
students or number of employees.
As described previously, the proposed project involves several elements throughout the building—
relocating administration spaces, counseling and career center, locker room modernization, and a science
classroom modernization and addition. The counseling/career center relocation would result in the
removal of one classroom, while the science addition would remove one classroom and add four
classrooms. The combined project would result in the net addition of two science labs, which are required
to support the changes to Washington State graduation requirements (increasing from 21 to 24 credits
with one additional science credit). Other changes are to meet ADA or equity standards.
The school’s existing enrollment capacity is 1,150 students and its current enrollment (as of fall 2021) is
1,106 students.3 There are currently 105 employees. The proposed renovation project would not change
the school’s enrollment capacity or staffing4 and would not result in any new daily or peak hour traffic
generation. Therefore, no additional traffic analysis should be required.
3. Parking Analysis
3.1. Supply and Code Requirements
The existing school site has a total of 338 parking stalls located in five areas—41 stalls in the north staff
lot, 42 stalls in the northeast staff parking lot, 50 stalls in the visitor and staff parking lot (including 8
parallel stalls), and 205 stalls in the student parking lot. The project would include partial resurfacing and
restriping within the student parking lot in compliance with City of Renton Municipal Code (RMP) and
slightly reducing supply in that lot to 199 spaces. At project completion, the entire site would have a total
of 332 parking spaces.
RMC §4-4-080.F.10.d outlines the parking requirements for a variety of land uses, including high
schools. The City requires a minimum of 1 parking space per employee plus 1 space for every 10
students. The school has 105 employees and will maintain its capacity of 1,150 students. Based on these
values, the City will require a minimum of 220 parking spaces (105 + (1,150 ÷ 10)). The planned parking
supply would meet City code requirements.
3.2. Typical School-Day Demand
School-day parking at high schools is influenced by staffing levels, family-volunteer activity, and student
drivers. ITE’s Parking Generation5 includes an equation and an average rate based on numbers of
students (equation: Ln(P) = 0.94 Ln(X) – 0.93 and average rate: 0.26-vehicles-per-student) for High
Schools (Land Use 530). Based on these, the school is estimated to have a school-day peak parking
demand of about 299 vehicles, which is likely to occur during late morning when students, teachers,
administrative staff, kitchen staff, and volunteers are typically on site. Afternoon demand may decline as
2 ITE, 11th Edition, September 2021.
3 Email communication, L. Brent, January 4, 2021.
4 Email, B. Tomlin, Architect, Facilities Project Manager – Capital Planning & Construction, RSD, Dec. 7, 2021.
5 ITE, 5th Edition, 2010.
Renton School District’s Lindbergh High School Renovation
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January 17, 2022 | 5
part-time and food-service staff leave after lunch. The on-site parking supply of 324 spaces can
accommodate this typical midday peak parking demand.
For comparison, demand counts were performed using aerial images of Lindbergh High School from May
2017 and May 2019,6 when the school had enrollments of 1,256 and 1,208 students, respectively.7 Those
counts found a total of 229 and 255 vehicles parked on site, which correspond to rates of 0.18- and 0.21-
vehicles-per-student for 2017 and 2019, respectively. These rates, derived specifically for Lindbergh High
School, are within but at the lower end of the range of rates on which ITE’s rates and equations are based.
Therefore, the ITE rates and equations provide a conservatively high estimate of demand for this site.
4. Summary and Conclusions
Based on the types of improvements and renovations proposed, the project would not change the school’s
current enrollment capacity or staffing level, and would not increase daily or peak hour trip generation.
The modified parking supply of 332 stalls, would continue to meet the City’s minimum code requirement
for parking, and accommodate the school-day peak parking demand. Therefore, no further transportation
analysis should be required.
TSM/tsm
RSD LHS Renovation Transportation Memo_FINAL
6 Google Earth, Aerial images accessed December 2021.
7 Office of Superintendent of Public Instruction (OSPI), School Report Card Enrollment Data., accessed December 2021.