East Marginal Way Corridor Improvement Project

Updated: July 7, 2020 

What’s happening now?

Thank you to everyone who participated in the 90% design survey. We reached the 90% design milestone for Phase 1 of the project in June. Major project elements have been finalized, but your input will help inform decisions made about wayfinding signage and expected impacts and detours during construction. 

We expect to complete Phase 1 design later this year and move into construction of this work in 2021. Phase 1 construction includes the following: 

  • Two-way protected bike lane (PBL) on the east side of East Marginal Way S between S Atlantic St and S Spokane St 
  • Reconstructed intersection at S Hanford St and a new traffic signal at S Horton St 
  • Lighting and landscaping along the PBL 
  • Potential relocation of train tracks at S Hanford St  
We used your feedback from the 60% design survey to make some improvements to the design of Phase 1. The biggest changes you'll see are:
  • Reconfigured PBL on the northeast corner of S Horton St. We adjusted the merge between the two PBLs to occur further north of the intersection
  • Redesigned driveway for Terminal 25 South (about 200 feet north of S Spokane St). We worked with the Port of Seattle on a proposed design that would improve visibility for people on bicycles and freight traffic
  • Addition of a berm to prevent debris from reaching the PBL. We added a berm in the landscaped area in places where there are no barriers

We continue to pursue funding for other segments of this project. Visit our project library at the bottom of this page to see more information about project features and schedule, review our federal grant proposals, and look at detailed design plans.

Comments and questions are welcome by emailing EastMarginal@seattle.gov or calling 206-684-8105.

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Project Overview

As Seattle grows, improvements to freight mobility are essential to promote regional and international economic competitiveness. East Marginal Way is a major freight corridor that provides access to the Port of Seattle terminals, rail yards, industrial businesses and the regional highway system, and between local Manufacturing and Industrial Centers (MIC's). It is also a designated Heavy Haul Route, critical last-mile connector and vital route for over-sized trucks or those carrying flammable cargo.  In addition, the corridor provides a major connection for people who bike between the West Seattle Bridge Trail, downtown, and the SODO neighborhood.

This project will:

  • Improve safety and reliability in the movement of people and goods
  • Support freight loads by rebuilding the roadway
  • Promote efficiency through signal modifications and intelligent transportation systems (ITS)
  • Improve safety by better separating non-motorized modes from freight traffic

Click here to view the 60% design overview.

Project Details

North Segment

For the North Segment (S Atlantic St to S Spokane St), design includes:

  • 2-way protected bike lane on the east side of the street between S Atlantic St and S Spokane St
    • From S Atlantic St to approximately S Massachusetts St, this bike lane would be under the SR-99 Viaduct
    • From S Massachusetts St to approximately S Holgate St, the bike lane would be to the east of E Marginal Way with a significant buffer from the roadway
    • From S Holgate St to S Hanford St, and in some sections between S Hanford and S Spokane St, the bike facility will be adjacent to the roadway but buffered by a concrete barrier
  • Multi-use path on the west side of the street between S Horton St and S Spokane St
  • New signalized diagonal bicycle crossing at E Marginal Way S and S Horton St
  • Reconstructing the E Marginal Way S roadway to heavy haul standards from approximately S Massachusetts St to S Spokane St
  • Replacing the existing water main in areas where the roadway will be reconstructed north of S Horton St
  • Rebuilding the sidewalk on the west side of E Marginal Way S adjacent to the roadway reconstruction north of S Horton St

North Segment cross section.

East Marginal Plan View - Hanford Options
PBL crossing at S Hanford St
East Marginal Plan View - Hanford Horton Options
PBL crossing at S Horton St

These recommendations are based on the public’s desire to reduce conflicts between bicyclists and trucks accessing Port of Seattle driveways and are consistent with existing northbound bike flow. Our design team evaluated placing the diagonal crossing at S Hanford St to take advantage of the existing traffic signal, however our analysis shows less delay for all users if we create a new signal at S Horton St.

Central Segment

This project aims to provide a clear route through the confusing area between S Spokane St and Diagonal Ave S.

Our proposed design includes a shared use path on the east side of E Marginal Way S south of S Spokane St. At approximately mid-block, the path will cross to the west side of the street at a marked crosswalk, where it will continue to Duwamish Ave S. From Duwamish Ave S, people walking and biking will use a marked crosswalk to continue on the west side of E Marginal Way S past the concrete plant. This would mark the beginning of a multi-use pathway heading south.

Freight improvements proposed in the central segment include reconstructing the surface street of E Marginal Way S to heavy haul standards, improving wayfinding and lighting to make it easier to navigate the area, and ITS improvements including a Dynamic Message Sign at S Alaska St.

Proposed central segment improvements

South Segment

The South Segment (Duwamish Ave S to 1 Ave S) is part of SR 99. There are neither bike facilities nor sidewalks on the west side of the street, and some missing sidewalks on the east side. These factors contribute to a challenging walking and biking environment for people trying to move through the area. 

In March 2018, SDOT completed a preliminary design for this section that included:

  • Pedestrian improvements at each existing traffic signal
  • Constructing missing sidewalks on the east side of the street
  • Transit stop improvements
  • Signal enhancements where appropriate to improve predictability and safety for people walking and biking

We have developed a proposal to improve the connection to the 1st Ave bridge, however funding constraints will prevent this from being part of the core project scope. If we identify a grant opportunity that allows us to include this connection, we will do so.

Design and construction of this portion of the project is currently unfunded. We will continue pursuing funding opportunities to advance the South Segment but currently do not have a schedule for this portion of the project.

Initial analysis of this section of the project also included evaluation of whether a lane of traffic on SR 99 could be removed to allow construction of a protected bike lane, as called for in the Seattle Bicycle Master Plan. Due to traffic volumes on SR 99, removing a motor vehicle lane was not recommended.

East Marginal Map South Segment
Click to enlarge

Project Benefits

  • Improved freight mobility –Support the economic vitality of our region including the Port of Seattle and local industrial businesses.
  • Safety - Better access and connections in combination with separating non-motorized modes to reduce potential conflicts.
  • Better pedestrian and bike connections – New and upgraded facilities for people walking and biking also improves access for employees using transit or non-motorized modes to get to work in the area.

Project Funding

Funding to evaluate alternatives and complete early design is provided by the 9-year Levy to Move Seattle, approved by voters in 2015. Learn more about the levy at Levy to Move Seattle.

In 2019, we secured grants to complete full design for the north and central segments, and to begin Phase 1 construction.

Schedule and Cost Estimate

The project is at 60% design completion. We expect to begin construction in 2021. SDOT will continue to pursue design and construction funding for additional phases of the project.

Phase 1 schedule


  • Data collection
  • Early design workshops
  • Preliminary traffic analysis


  • Online Open House and Survey from Spring to Summer
  • Spring
    • Develop options
    • Seek input on options
  • Summer
    • Create preliminary engineering designs
  • Fall
    • 10% design complete


  • Winter-Spring
    • 30% design complete


  • Restart design


  • Complete design for North and Central segments


  • Begin construction


  • Complete Phase 1 construction

Public Outreach

We are currently advancing design based on public input and comment collected from 2015 to present.

In fall 2019, we worked with businesses in the Central Segment to develop a preliminary concept for the area. We will continue working with businesses and community groups to develop design.

To request a briefing for your organization or for more information, please send an email to EastMarginal@seattle.gov.

Nearby Projects

S Lander St Bridge Project

Georgetown Mobility Study

Project Materials

Phase 1 90% Protected Bike Lane at S Horton St

Phase 1 90% Terminal 25 South Driveway

Phase 1 90% Design Plan Set

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 Sheet

East Marginal Way project INFRA grant, submitted 2/25/20

Project Contact

Dan Anderson, Communications Lead

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