E Marginal Way S Paving and Safety Improvements

4th Ave S to Corson Ave S

Corson Ave S to Carleton Ave S

Carleton Ave S to S Ellis St

Ellis Ave S to 16th Ave S

16th Ave S to city boundary

Street Redesign

Moving freight and goods remains a priority for this Major Truck Street that serves port facilities, cargo yards, and major businesses. This distinction and the importance of maintaining freight reliability was carefully considered as we developed the new street design. 

The new design enhances safety for everyone by encouraging safer driving speeds, improving visibility at crossings, and making the movements of all travelers more predictable. The project further separates travelers who walk, roll, and bike from faster-traveling traffic. The design also improves bike connections between Duwamish Valley neighborhoods and West Seattle. 

Southbound Lane Reduction

During the planning process, we collected data on E Marginal Way S and determined the removal of one southbound lane from 4th Ave S to S Ellis St would not reduce the level of service for freight. This lane reduction would allow us to extend the shared use path to Corson Ave S and install protected bike lanes up to S River St. We are adding a bike crossing at the south leg of the E Marginal Way S / 4th Ave S / S River St intersection. The bike crossing will tie-in with a planned SDOT bike project on S River St that will connect with the 1st Ave S Bridge Trail. 

The numbers represent average daily traffic (vehicles) based on 7-days. (SDOT traffic data)  

Anticipated delays per vehicle along E Marginal Way S based on our traffic analysis:

• S Michigan St
  • No anticipated delays
• 4th Ave S
  • AM Peak – 1 second delay
  • PM Peak – 10 second delay
• Corson Ave S
  • AM Peak – no anticipated delays
  • PM Peak – 1 second delay
• Carleton Ave S
  • AM Peak – 1 second delay
  • PM Peak – 1 second delay
• Ellis Ave S
  • AM Peak – 4 second delay
  • PM Peak – 3 second delay
• 14th Ave S
  • AM Peak – no anticipated delays
  • PM Peak – 4 second delay
• 16th Ave S
  • AM Peak – 1 second delay
  • PM Peak – 1 second delay 

What bike and pedestrian facilities will this project build connections to?

• The SDOT Bike Web Map shows all of Seattle’s bike facilities. This project will improve access to the 1st Ave S bridge trail, the Duwamish River trail, the Georgetown to South Park trail, and the Georgetown to Downtown bike lanes which connect to the SODO trail into the downtown bike network.
• Our project includes directional protected bike lanes with pre-cast curbs from 16th Ave S to the approach of the Seattle/Tukwila city line. We are working with the City of Tukwila to ensure our design plans are compatible with their plans. This project will improve access to and from the Green River Trail but does not connect directly to it.
• As part of a separate planned project that will create a bike route along S River St and connect to the 1st Ave S Bridge Trail, SDOT will install a two-way bike crossing at the south leg of East Marginal Way S and 4th Ave S.

Why does SDOT want bike lanes on freight corridors? Wouldn't bike lanes on other streets be safer and better for traffic?

• This project builds connections to existing and future bike and pedestrian routes to make it safer for people to walk and roll where they are already traveling or where future developments will route them.
• E Marginal Way S offers the most direct routes to existing transit stops and existing bike and pedestrian facilities like the 1st Ave S bridge trail, the Duwamish River trail, the Georgetown to South Park trail, and the Georgetown to Downtown bike lanes which connect to the SODO trail into the downtown bike network.

How many people walk and bike in this area today? How much to you expect that to increase with this project?

• We did not conduct a bike and pedestrian traffic count in this area. This paving project triggered a redesign of the corridor to be in compliance with the city’s Complete Streets Policy (2007). The policy directs SDOT to design streets for people walking, rolling, biking, taking transit, and persons of all ages and abilities, while promoting safe operations for all users.
• This isn’t a popular bike route currently because there isn’t an existing bike facility that feels comfortable for most riders. Once this project is built, we expect more people will walk, roll, and bike along the corridor as they become aware of the new travel options and more comfortable with using them. These numbers will grow as we continue to build these options throughout the City and especially in South Seattle.

How will this project design safe routes for cyclists and pedestrians through intersections and driveways?

For people walking and rolling through intersections, early design enhancements along the corridor, include:

• Inspecting and reconstructing curb ramps to make them compliant with the Americans with Disabilities Act (ADA)
• Installing Leading Pedestrian Intervals, which is a traffic signal timing strategy that allows pedestrians to enter the crosswalk 3-7 seconds before vehicles receive a green light, enhancing pedestrian safety and visibility
• Installing Accessible Pedestrian Signals, which provide auditory, visual, and vibrotactile information
• Installing curb bulbs to reduce crossing distances and improve visibility at key intersections and slow down drivers making right turns with the sharper turn radius

For people biking:

• We will use green high-visibility pavement to identify bike lanes through driveways and intersections.
• We are working closely with businesses in the area and can install additional safety features like signage and lights if additional protection is needed through driveways and intersections with higher traffic volumes.  
• The early design improvements will upgrade signals with dedicated turn phases to support the new bike lanes and reduce conflicts
• We’ve done a full lighting analysis of the corridor and plan to upgrade lighting
• We are trying to concentrate the driveways into narrow places so that people biking and walking can know where to expect cars coming from and going

Will these roadway changes impact freight routes?

• We’ve engaged with many industrial stakeholders along the corridor to understand their access and operational needs. The project will not only preserve access on this busy corridor but includes enhancements—in addition to paving—that will be beneficial for freight and other trucks travelling through this corridor.
• We are working with the Seattle Freight Advisory Board and will address any challenges they see with the design to prevent truck routes needing to move. We know E Marginal Way S is an active freight corridor and this project will preserve access.

Why is the project reducing southbound E Marginal Way S from 2 lanes to 1 lane? How will the lane reduction impact traffic on E Marginal Way S and neighboring streets, considering growing numbers of people and cars?

• With limited roadway space, it wasn’t possible to add walking and biking facilities for the half mile between 4th Ave S and Ellis Ave S without decreasing the space dedicated to cars and trucks.
• The lane reduction will also help improve safety on E Marginal Way S. One of the Vision Zero strategies to design safer streets is reducing lanes on multi-lane roads, which helps reduce vehicle speeds and conflict points to prevent crashes.
• North of the 1st Ave S bridge on E Marginal Way S, traffic counts are much higher (around 42,500 travelers per day) than they are south of the bridge (around 5,500 to 15,500 travelers per day).  
  We completed a traffic analysis for reducing E Marginal Way S from 2 to 1 southbound lane between 4th Ave S and Ellis Ave S. The analysis concluded that all intersections would maintain their current levels of service, with only minor delays. Expected delays range from 0 to 10 seconds per vehicle.
• Because we only expect the lane reduction to increase travel times slightly, driving on main roads will still be faster than cutting through neighborhood streets. The recent Georgetown Healthy Street project added traffic calming measures including speed humps to Carleton Ave S and S Flora St to prevent speeding.

Why is the project removing the right slip lane from E Marginal Way S to 4th Ave S? Will trucks still be able to make this turn?

• We originally described the changes to the turn lane from northbound E Marginal Way S onto 4th Ave S as the removal of a slip lane, but the 4th Ave S lane is really a wider receiving lane. We are reducing the southeast corner radius and adding a “truck apron” at the northeast corner of the E Marginal Way S and 4th Ave S intersection.  
• This design uses a Vision Zero strategy of designing tighter turns that encourage drivers to slow down. The truck apron allows larger vehicles to drive over a portion of the widened curb to make the turn less tight, which we confirmed with a turn analysis.
• Below is an example of a truck apron we installed recently at the Airport Way S and S Lucile St intersection.
  

How often are the railroad tracks parallel to E Marginal Way S used? Could this project remove some tracks that aren’t utilized?

• We are not sure how frequently these tracks are used, but what matters is compatibility, which we will ensure. We're in conversation with Union Pacific Railroad now to understand what impact the project will have on their operations.  
• Unfortunately removing tracks would be out of the scope of this project. It is difficult to work with the railroad and it would likely add time we don't have.

What bus routes are served along this route? Are there going to be a bus/freight lanes along the entire project?  

• This portion of E Marginal Way S is a part of routes 60 and 124.
• We are not building bus/freight only lanes, but we are working with Metro to explore ways to improve bus operations, including signal hardware upgrades to enable Transit Signal Priority.

How does this project address long-term safety and climate goals? Why is the project lifespan only 10-20 years?  

• During the project's planning phase, we reviewed recommendations from past planning efforts such as the Georgetown Mobility Study, the Seattle Transportation Plan, and the Duwamish Valley Action Plan.
• The average lifespan of roadway pavement is 15-25 years. Since E Marginal Way S is used by more trucks and other heavy vehicles than other roads, we expect the lifespan of this repaving to be shorter than average. The other improvements to pedestrian, bike, and transit facilities, we expect to be longer lasting, but they may also need upgrades when the next repaving happens.
• This project adds pedestrian, bike, and transit infrastructure in and between communities that have historically needed to rely on cars. These changes will make getting around without a personal vehicle easier for the people who live and work in Georgetown, South Park, and SODO and will help pave the way for making this area of Seattle less reliant on cars.

What type of trees will be planted and where? How will the new trees planted by the project be maintained?

• We do not yet have specific tree types planned. The tree type will depend on planting strip width and overhead clearance, with a goal of maximizing tree canopy. The tree types will be ones well suited for the environment, meaning they will be less likely to cause cracking in sidewalks and roadways, and they won’t need to be pruned very often to maintain clearances for trucks, buses, and power lines.
• The street trees installed by the project are SDOT assets and will be maintained by SDOT Urban Forestry or Seattle City Light, depending on the need for pruning. The contractor will maintain the street trees for one year after they are installed, and then SDOT Urban Forestry will take over establishment care for four more years. Establishment care includes watering in hotter months and establishment pruning to encourage branches to grow away from travel lanes and overhead power lines. Once establishment care is complete, the street trees should be mature enough to survive on their own without supplemental water.  

How will the bike lanes be maintained, especially during fall/winter with leaves and rainwater?

• E Marginal Way S is currently swept weekly as part of sweeping route 105. Because only some street sweepers are small enough to clean bike lanes, the new bike lanes would likely be swept less than weekly but still regularly.
• Drainage improvements at Corson Ave S, Carleton Ave S, S Myrtle St, Ellis Ave S, and 16th Ave S will help prevent rainwater pooling in the bike lanes.
• Users can also report broken or damaged bike facilities, including debris, slippery wet leaves or standing water on the bike lane using SDOT’s Find It, Fix It app (or calling 684-ROAD). You can read more details on this SDOT blog post. 

Why does the design direct cyclists to use the sidewalk on the north side of E Marginal Way S at the S River St intersection? 

• The short stretch of sidewalk along E Marginal Way S where we’re directing cyclists is 10 ft wide, which is wider than a standard sidewalk. We aren’t calling it part of the shared use path because it would require using up some of the space to add landscaping for protection. Due to limited space, we made a wider sidewalk to accommodate users rather than creating a substandard shared used path with landscaping. 

• 60% Design Plans
• Early Design Outreach Summary
• Early Design Online Open House Presentation
• Lane Reduction Traffic Analysis
• Early Design Cross Sections
• Early Design Roll Plot
• Fact Sheet
  • English
  • Hoja informativa (Spanish)
  • 概況介紹 (Chinese Traditional)
  • TỜ THÔNG TIN (Vietnamese)
  • 사실 보고서 (Korean)
  • ファクトシート (Japanese)

We’re coordinating with nearby design projects and existing projects in the neighborhood. Learn more about nearby projects by visiting their websites linked below: 

• Georgetown to Downtown Safety Project
• Georgetown to South Park Connection
• Georgetown Off-Leash Dog Area
• East Marginal Way Corridor Improvement Project
• 14th Ave S Reimagined
• 4th Ave S sidewalk improvement project – This project is planning sidewalk upgrades on 4th Ave S north of E Marginal Way S to be installed as soon as 2027.
• Email the Pedestrian and Bike Program at walkandbike@seattle.gov for questions regarding the following projects: 
  
  • Future Neighborhood Greenway connection along S River Street to 1st Ave S Bridge.    
  • New crossings on S Willow St – The Neighborhood Greenway program is proposing two new crossings on S Willow St. A new crosswalk with a rapid flashing beacon (RFB) at S Willow St and Corson Ave S has been added to a Vision Zero project that is planned to be installed in 2026.  
  • Crossing improvements at Ellis Ave S – New crosswalks with an RFB will be added on Ellis Ave S at S Willow St, S Warsaw St, and S Bailey St. This project is in the early planning phase, and more information will be available later this year. 
• Vision Zero – A project is coming to Corson Ave in 2026 to calm vehicle traffic, facilitate safer crossings, and supplement neighborhood greenway work and the Georgetown to South Park Trail. A new crosswalk with a rectangular rapid flashing beacon (RRFB) at Corson Ave S and S Willow St will be installed. The project is currently at 90% design and anticipate it to be implemented sometime this year. You can expect standard parking restrictions during construction, but there will be no long-term changes to on-street parking.    
• Georgetown Healthy Street Enhancements – This project will begin design and outreach for upgrades to the Georgetown Healthy Street on Carleton Ave S between S Eddy St and S Willow St. These upgrades include adding large street trees, potentially expanding Oxbow Park, and making other public space enhancements.