East Marginal Way Corridor Improvement Project
Updated August 27, 2025
What's Happening Now?
Night closures on E Marginal Way S August 25-28
E Marginal Way S between S Atlantic St and S Spokane St will be closed overnight from Monday, August 25 to Thursday, August 28. These overnight closures will allow crews to safely perform roadway striping work. Closures will begin at 7 PM each evening and the roadway will open at 5 AM each morning.
What to expect
- Nighttime closures of E Marginal Way S between S Atlantic St and S Spokane St from Monday, August 25 to Thursday, August 28 from 7 PM to 5 AM
- Access will be maintained for Port of Seattle Police, Terminal 30, and the U.S. Coast Guard via southbound travel from S Atlantic St
- Access for people walking, biking, and rolling through the corridor will remain open during the closures
Walking, biking, and rolling on E Marginal Way S
People walking and biking on E Marginal Way S are routed onto the new bike path from just north of S Spokane St to S Horton St. North of S Horton St, people walking and biking are detoured onto our new concrete pavement on the west side of the roadway.
Our goal is to minimize disruptions and maintain safe access for people walking, biking, and rolling along the corridor during construction. Construction is dynamic. Our crews prioritize safety while planning and managing route changes through the work zone. When routes change, our team puts up signs, updates traffic stencils, and clears debris to support safety and reliability for people traveling. Do your part to keep yourself and others safe while travelling through the corridor by slowing down, following directions from flaggers, and watching for equipment and signs.
General purpose traffic
E Marginal Way S is closed to general purpose traffic between S Spokane St and S Atlantic St for the duration of construction. General purpose traffic is detoured onto 1st Ave S or nearby streets. See detour map below.
Access is maintained for people walking, biking, and rolling along E Marginal Way S using different routes to avoid active construction areas.
Port of Seattle and freight traffic
Northbound access for Port of Seattle and freight traffic is maintained between S Spokane St and S Massachusetts St, and two-way local access is maintained between the Jack Perry Memorial Park driveway and S Atlantic St. Port of Seattle and freight traffic should expect lane closures, detours, and flagging on S Hinds St, S Horton St, and S Hanford St for 4 to 8 weeks. We will avoid having impacts at the S Horton St and S Hanford St intersections at the same time and local access will be maintained.
Overview
E Marginal Way S is a major freight corridor that provides access to the Port of Seattle terminals, rail yards, industrial businesses, and between local Manufacturing and Industrial Centers (MICs). It is also a designated Heavy Haul Route, critical last-mile connector, and vital route for over-sized trucks or those carrying flammable cargo. The corridor also provides a major connection for people who bike between the West Seattle Bridge Trail, downtown, and the SODO neighborhood.
This project will deliver the following benefits to people driving, walking, biking and rolling on E Marginal Way S:
- Freight mobility – Supporting the economic vitality of our region with improved freight access to the Port of Seattle and local industrial businesses
- Safety – Promoting safety with new separated facilities and upgraded connections for people walking, biking, and rolling
- Efficiency – Optimizing travel for all users with new signal modifications and intelligent transportation systems
The East Marginal Way Corridor Improvement Project extends along E Marginal Way S from S Atlantic St to 1st Ave S, and is divided in three segments: North, Central, and South. Each segment is moving at its own schedule so that we can deliver improvements more quickly as funding becomes available.
Check out the Project Segments section below to learn more about each segment and its status.
Project segments
- North Segment - S Atlantic St to S Spokane St
- Central Segment - S Spokane St to Diagonal Ave S
- South Segment - Duwamish Ave S to 1st Ave S
Select each segment below for more information about the design and schedule.
East Marginal Way Segments
North Segment
The North Segment runs from S Atlantic St to S Spokane St.
North Segment Construction began in March 2024 and major work is expected to end in fall 2025. North Segment improvements will reduce conflicts between people biking and trucks accessing Port of Seattle driveways and increase safety and efficiency through the corridor.
Freight improvements
- Full street reconstruction with a new 15-inch thick concrete street to better support heavy freight trucks
- Vehicle weigh-in-motion system to help SDOT track wear and tear on the street
- Revised intersection at S Spokane St for safer turning movements
- Redesigned driveway at Terminal 25 South to improve visibility for people biking and driving
Signal improvements
- Dynamic message sign at S Alaska St and E Marginal Way S
- Rebuilt traffic signal at S Hanford St and new signal at S Horton St
Improvements for people biking, walking, and rolling
- New two-way protected bike lane on the east side of the street between S Atlantic St and S Spokane St
- Shared-use path for people walking and biking on the west side of the street between S Horton St and S Spokane St
- New diagonal crossing with signal for bike traffic at S Horton St
- Rebuilt sidewalks on the west side of E Marginal Way S
- New ADA-compliant curb ramps to increase access to sidewalks
S Atlantic St to S Massachusetts St
S Hanford St to S Horton St
S Horton St to S Spokane St
Central Segment
The Central Segment runs from S Spokane St and Diagonal Ave S.
Central Segment design is nearly complete and work will continue as funding is identified. Planned improvements in the Central Segment include:
- Reconstructing the surface street of East Marginal Way S to heavy haul standards between S Spokane St and Duwamish Ave S
- Improving wayfinding and lighting
- Installing a Weigh-in-Motion system for northbound traffic at Duwamish Ave S
- Realigning the southwest corner of Diagonal Ave S and East Marginal Way S to improve the turning radius for eastbound trucks making a right turn
- Adding a new shared-use path for people walking, biking, and rolling starting south of S Spokane St and continuing to Diagonal Ave S. Due to space constraints, the shared-use path will begin on the east side of the street and then transition to the west side of the street with a marked crosswalk.
South Segment
The South Segment is currently in the preliminary design phase, and work will continue as funding is identified. Planned improvements in the South Segment include:
- Pedestrian improvements at each existing traffic signal
- Constructing missing sidewalks on the east side of the street
- Bus stop improvements
- Signal enhancements where appropriate to improve predictability and safety for people walking and biking
- Improve pedestrian and bicyclist connectivity to the 1st Ave S bridge
Benefits
Funding
Funding to evaluate alternatives and complete early design was provided by the 9-year Levy to Move Seattle, approved by voters in 2015. Learn more about the levy at Levy to Move Seattle website. In 2019, we secured grants from Transportation Improvement Board (TIB) and Federal Highways (FHWA) to complete full design for the north and central segments. In November 2021, we secured remaining grant funding to construct the North Segment of the project. North Segment funding partners include:
- Freight Mobility Strategic Investment Board (FMSIB)
- Transportation Improvement Board (TIB)
- Port of Seattle
- Federal Highways (FHWA) funds from PSRC and RAISE
| Segment | Design Funding | Construction Funding |
| North | Yes | Yes |
| Central | Yes | No |
| South | No | No |
Schedule
This project began in 2015 and has advanced project planning and design through consistent engagement with community members, businesses, partner agencies, and community advocacy groups.
Planning phase (2015 - 2016)
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Data collection and preliminary traffic analysis
-
Early design workshops
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Community engagement through online open house and survey
Design phase (2017 - 2023)
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North Segment - completed design in summer 2022
-
Central Segment - reached 90% design in summer 2023
- South Segment - preliminary design completed
Construction of North Segment (2024- 2026)
-
Construction began in March 2024
Project Materials
- North Segment pre-construction factsheet (Winter 2024)
- Project factsheet - all segments (Winter 2024)
- North Segment factsheet (May 2022)
- 90% design rollplot (May 2022)
- Project factsheet (Updated October 2021)
- State Environmental Policy Act (SEPA) Documentation
- RAISE Grant Application (July 2021)
- Freight Survey SummaryPhase 1
- 90% Protected Bike Lane at S Horton St
- Phase 1 90% Terminal 25 South Driveway
- Design Rollplot
- US Department of Transportation BUILD grant
- 60% Frequently Asked Questions
- 60% Outreach Summary
- 60% Design Overview Phase 1
- 60% Design Plan Set (selected sheets)
- Phase 2 60% Design Plan Set (selected sheets)
- Project Fact SheetEast Marginal Way project
- INFRA grant, submitted 2/25/20
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