West Marginal Way SW Improvements

What's Happening Now?

Thank you for attending our virtual Open House on Feb 18 for the West Marginal Way SW Improvements Project. We want to assure you that we heard everyone's thoughts and concerns. 

View the PowerPoint presentation from Feb. 18 or watch the full meeting on YouTube

We will be responding through our Open House summary, which will be posted on this website along with the PowerPoint presentation and a recording of the meeting very soon. Thank you for your patience as we continue to track community feedback following the Open House.

We encourage you to read the most current information about the project, below. If you haven't already done so, please also take a few minutes to complete our online Business Survey by following this link: West Marginal Way SW Business Survey (qualtrics.com)   

We have not made a decision about the final design for West Marginal Way SW at this time. Our decision will be guided by the Freight Master Plan, Bicycle Master Plan, our Vision Zero and mode shift goals, data, and input from local community members such as yourself.  

Learn about this project through our video, available in multiple languages:

Project Background

West Marginal Way SW connects communities and industrial businesses along the western bank of the Duwamish Waterway. It is a major truck street between bridges and connects to Port of Seattle facilities. The street also provides direct access to the Duwamish Longhouse and Cultural Center, parks, and residences as well as shipping, manufacturing, and maintenance centers. The Duwamish Trail, a multi-use recreational path for people walking and biking, runs alongside West Marginal Way SW for several miles.

Since the closure of the West Seattle High-Rise Bridge in March 2020, we have seen an increase in the number and speed of people driving on this busy corridor. Due to this detour, average weekday traffic volumes on West Marginal Way SW have increased by over 150%, from 9,760 vehicles to 24,880 vehicles on an average weekday. This project is designed to make the street safer, more convenient, and more comfortable for everyone, and encourage people walking and biking - our vulnerable users - to use West Marginal Way. Each of these improvements can bring us closer to our Vision Zero goals and help to provide alternatives for the traveling public that reduce demands on the road network.

Graphic showing the project area for West Marginal Way

Project Decsriptions

1. Duwamish Longhouse: New pedestrian signal, new crosswalk, and new sidewalk

Speeding vehicles and higher traffic volumes on West Marginal Way SW can create access and safety challenges for people trying to access the Duwamish Longhouse. In 2021, SDOT will build an interim pedestrian signal and painted crosswalk at the Duwamish Longhouse (4705 West Marginal Way SW). This interim signal will stop traffic for people crossing West Marginal Way SW.

SDOT will plan and design a permanent signal for this same location in as soon as 2022. Additionally, SDOT will install a sidewalk in 2021 on the west side of West Marginal Way SW between the Duwamish Longhouse and SW Idaho St to upgrade the dirt path. A new sidewalk will provide direct access for people in wheelchairs and rolling to the Duwamish Longhouse from the parking lots on the east side of West Marginal Way SW and meet Americans with Disabilities standards. 

Graphic showing the Duwamish Longhouse project on West Marginal Way

Proposed improvements at Duwamish Longhouse

Pedestrian safety improvements at the Duwamish Longhouse include a new pedestrian signal, crosswalk, and sidewalk.

2. Bike network connections

Community feedback in 2020's Reconnect West Seattle survey indicated a desire for better bike connections along West Marginal Way SW. Based on community interest and SDOT's evaluation of options, we are proposing a protected bike lane along the west side of the street from SW Marginal Pl to the Duwamish Trail signal just south of SW Idaho St.

Graphic showing proposed bike project area for West Marginal Way

Cross section of proposed bike lane along West Marginal Way SW (looking north)

Benefits of a protected bike lane on West Marginal Way SW

  • Protected bike lanes separate people biking from traffic, creating safer and more comfortable spaces that attract a wide range of people who bike. Increasing bicycling meets multiple long-term City goals for safety, sustainability, traffic, and health.

  • Fills in a gap in the Duwamish River Trail and creates more seamless connection for people biking to and from  the West Seattle Bridge Trail, Alki Trail, and SW Avalon Way.

  • Completes a project in the Bicycle Master Plan.

  • Increases multimodal travel options as part of Reconnect West Seattle mobility projects.

  • Minimizes effects on vehicle travel: anticipated 10 second travel time effect on southbound drivers during peak hours, with no effect on northbound drivers.

  • Reduces speeding and eliminates right-lane passing by removing the outside (right) lane, currently only used by 1 out of every 5 southbound drivers. 

3. Design options for the west side of West Marginal Way 

There are three design options for the west side of West Marginal Way SW to the south of the proposed bike lane.

Graphic showing proposed options for west side of West Marginal Way

Option a) Extend the Proposed bike lane south to the Duwamish Longhouse crossing signal

Option a) Extend the Proposed bike lane south to the Duwamish Longhouse crossing signal

  • Provides direct access for people biking to the Longhouse

  • Maintains on-street parking in front of the Longhouse

  • Overlaps with Duwamish River Trail on the east side of West Marginal Way  

Option b) Extend the existing on-street parking north to the Duwamish Trail signal

Option b) Extend the existing on-street parking north to the Duwamish Trail signal

  • Provides 30 additional on-street parking spaces for Longhouse access, freight parking, and Herring's House Park overflow

  • Complements new sidewalk being installed on west side of West Marginal Way  

Option c) Remove lane drop, opening the outside (right) lane back up to general traffic

Option c) Remove lane drop, opening the outside (right) lane back up to general traffic

  • Reintroduces sightline issue for drivers leaving Longhouse parking lot

  • Removes on-street parking in front of Longhouse

  • Likely to increase vehicle speeds along this stretch of West Marginal Way

  • Negligible change to southbound travel times

3. Speeding 

We are committed to Vision Zero goals of reducing motorist speeding, crashing, and fatalities. In 2020, we installed six speed radar signs along West Marginal Way SW to help reduce travel speeds from 40 mph to 30 mph. We found that the radar feedback signs reduced vehicle speeds by up to 11% so far.

Speed radar sign

Project Timeline 

Winter 2021

  • Engage area businesses, community partners, and neighbors.

  • Outreach to businesses along West Marginal Way via online business survey 

  • Mailer to West Seattle residents 

  • Virtual Open House on February 18, 2021

Spring 2021

  • Compile and analyze feedback

  • Select preferred design option Summer-Fall 2021

  • Project construction and completion

Community Engagement  

We are committed to working with the community to keep you informed of progress and milestones as we rehabilitate the bridge. We will seek your continued feedback on how to improve mobility and safety for West Seattle, as well as the South Park and Georgetown neighborhoods. Thank you to everyone who has helped us make this project better with your ongoing engagement. 

Learn more, get involved, and tell us what you think:

Project Materials

West Seattle Transportation Coalition Meeting Presentation (1/28/21)

Project mailer (English - 1/21) 

Translated project information

West Marginal Way Business Survey (2/4/2021)