Link to Transportation Home Page Link to Transportation Home Page Link to Transportation About Us Page Link to Transportation Contact Us Page
Delivering a first-rate transportation system for Seattle Scott Kubly, Director







Site Index

Neighborhood Planning Home Page
Accessible Mt. Baker
Judkins Park Station Access Study
Georgetown Mobility Study
Move Ballard
One Center City
Center City Circulation Report
Central Business District Curbspace Study
Southeast Transportation Study (SETS)

South Lake Union Transportation Study

Good news for all of us who want progress on Seattle's transportation problems, including the Mercer "mess". The South Lake Union Transportation Study presents a package of transportation improvements for the South Lake Union area, with broad support from a diverse group of neighborhood, business and community representatives.

The improvements call for a two-way Mercer Street, streetcar and a number of other transit, pedestrian and bicycle measures that, taken together:

  • reconnect a growing neighborhood to the City;
  • untangle streets that create barriers in the middle of Seattle;
  • improve mobility for people in Queen Anne, Capitol Hill, Eastlake and surrounding neighborhoods that use this corridor;
  • promote transit, walking, and biking; and
  • continue a smooth flow of freight and people through the corridor.

This package emerges from the South Lake Union Transportation Study that was prepared with the help of our consultants, Parsons Brinckerhoff and EnviroIssues. The study documents the analysis and review of existing conditions, reports on suggestions from the public, identifies issues and alternatives, and produces the recommendations described here.

Letter from Grace Crunican, Director, Seattle Department of Transportation, about South Lake Union Transportation Study (PDF format)

South Lake Union Transportation Study - Full Report (20 MB, PDF format)

Updated on 10/19/04 - Overview of SLU Transportation Study - Brochure (PDF format)

News Release - Agreement Reached on Mercer "Mess" - South Lake Union Report Reflects Consensus on Transportation Package - July 30, 2004

South Lake Union Transportation Study - By Chapter:

South Lake Unions potential is enormous. Research and manufacturing will bring jobs, housing and neighborhood amenities. Its up to us to put the transportation foundation in place to make it happen.
Mayor Greg Nickels

What is the South Lake Union Transportation Study?

By 2020, South Lake Union will be home to 20,000 new jobs and 10,000 new housing units. Already South Lake Union has exceeded the 1994 Comprehensive Plan growth target for jobs in this neighborhood. To prepare for this new influx of growth and to fix existing conditions like the Mercer "mess", the Seattle Department of Transportation conducted the South Lake Union Transportation Study. The study coordinates analysis and recommendations identified through the South Lake Union Neighborhood Plan, the Alaskan Way Viaduct and Seawall Project, the Mercer Corridor Project and other recent planning efforts.

Study Vision: Develop transportation strategies to support the development of the South Lake Union Urban Village

Study Goals

  • Improve mobility and access for pedestrians, bicycles, vehicles and transit within and between South Lake Union, surrounding neighborhoods and downtown,
  • Improve safety of all transportation modes,
  • Improve regional access to and through South Lake Union,
  • Promote economic vitality, sustainable development, neighborhood livability, and quality of life for current and future residents and businesses, and
  • Work towards implementing Comprehensive Plan goals and other City policies and plans

How was the study funded?

The study is funded by money from the sale of City-owned properties in the South Lake Union area. These properties were originally purchased for the Bay Freeway project in the 1960s. A portion of the property proceeds is designated for transportation improvements in South Lake Union.

Key Recommendations from the Study include:

Street Improvements

  • Two-way, seven-lane Mercer Street
  • Narrow Valley Street
  • Aurora overpass at Thomas or Harrison Street
  • Two-way Westlake and Ninth avenues


  • Streetcar on Westlake and Terry avenues
  • New bus route between Uptown and North Capitol Hill
  • Increased frequency on Bus Route 8
  • Transit Signal Priority reducing delays for buses on Fairview Avenue

Pedestrian and Bicycle

  • Wider sidewalks and more crossings on Mercer and Valley streets
  • Bike path or lanes on Mercer Street across Aurora
  • Bike lanes on Valley and Roy streets connecting Fairview to Dexter
  • Bike route on Fairview Avenue north of Valley Street and on Ninth Avenue
  • Sidewalk on north side of Denny Way across I-5
  • Curb bulbs and pedestrian enhancements on Harrison and Thomas streets

Transportation Demand Management (TDM)

  • TDM programs coordinated among businesses and property owners
  • Support for transit, walking and biking
  • Parking management to encourage use of non-SOV modes and continue to provide customer access

We're listening to you

Over 100 people attended open houses in the beginning of the process to identify issues and at the end to comment on recommendations. In addition to the open houses a broad-based Stakeholder Group was formed to advise SDOT on issues and findings. Both SDOT and the stakeholders evaluated possible recommendations to determine their effectiveness in meeting study goals. The results of the evaluations were nearly identical, leading to the study recommendations.

South Lake Union Transportation Study Open House handout (PDF)

View boards from the March 2004 open house:
Conceptual Cost Estimates (PDF)
Proposed Mercer & Valley Streets (PDF)
Proposed Westlake & 9th Avenues (PDF)
Proposed Fairview Avenue (PDF)
Proposed Thomas & Harrison Streets (PDF)
Travel Time Summaries (PDF)
Transportation Demand Management - Balancing mobility and livability (PDF)

More Information and Related Projects

Discover South Lake Union (Discover SLU)

South Lake Union Transportation Projects

South Lake Union On-Street Parking Plan

South Lake Union Streetcar

Terry Avenue North Design Guidelines

South Lake Union Park
Mercer Corridor Project

Comment Form

Please provide your contact information so we may keep you informed of the project.





"For more information, please contact Tony Mazzella, SDOT Project Manager,, telephone 206.684.0811.

Home | About Us | Contact Us | Site Index | News | FAQs | E-Mail Alerts