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South Lake Union Transit Improvements

More Buses, More Options, More Seattle


Beginning Monday, March 21, the new bus lanes can only be used by buses 24/7. These changes are in preparation for new service from the RapidRide C Line to South Lake Union that will begin the following Saturday, March 26. Implementing the bus only lanes a week in advanced of the March 26 service change provides opportunity for drivers to adjust to the new bus lanes and also takes advantage of dry weather, producing higher quality markings.

The new northbound center BUS ONLY lane (between Harrison St and Mercer St) replaces the left turn lane from Harrison to Mercer. Additionally, people driving will be restricted from:

  • Making northbound left turn Westlake to Mercer.
  • Making southbound right turns from Westlake to Mercer.
  • Making northbound and southbound left turns from Westlake to Republican.
  • Making southbound right turns from Westlake to Republican.
  • Making northbound right turns from Westlake to Harrison.
  • Making southbound right and left turns from Westlake to Thomas.
  • Making northbound right turns from Westlake to Thomas.
  • Making northbound left turns from Westlake to Denny (during the middle of the day)

Please plan your new route in advance to allow for adjustments to the changes. SDOT would like to thank the public for its patience while this work is completed. 

New RapidRide C Line service and the SLU Streetcar will start using the BUS ONLY lanes. The changes make it possible to double the number of people using transit along Westlake Avenue during the afternoon peak commute between 5p.m. and 6 p.m. on weekdays, which is the equivalent of adding another travel lane.

Ready for more bus service? Learn about the New RapidRide C Line service coming to SLU starting March 26.


Since last June, Seattle has seen the largest increase in King County Metro bus service in 40 years; and the Move Seattle levy is making our streets work better for those taking transit. The project described below will make it possible for double the number of people to ride transit in South Lake Union during peak hours starting March 26, 2016.

  • New RapidRide C Line Extension operating every 7 to 12 minutes from W Seattle
  • More service on Route 40 operating every 9 to 15 minutes from Ballard/Fremont
  • More peak time service for Route 70 from the U District
  • More service and a shorter route for Route 8 from the Seattle Center and Capitol Hill/Rainier Valley
  • Dedicated transit lanes on Westlake Ave N
  • Transit stop upgrades

Project Description

Over the next few months we're building a series of improvements along Westlake Avenue N and Aloha and Valley Street, including new transit lanes and transit stop upgrades. These improvements accommodate shifting Route 40 to Westlake Ave N in both directions, more trips on Route 40 and very importantly, extending RapidRide C Line from W Seattle to Downtown. The transit lanes also benefit the Streetcar.

Project Map

Click on map for larger view

Key Features

To make transit work better, in addition to adding transit lanes, turn restrictions and removal or restriction of some on-street parking is required at the following locations:

New curbside bus only lanes will operate 24/7 except for a small portion between Ninth Ave N and Valley St. In this location they will be operate between 6AM to 7PM on weekdays.

  • Northbound Westlake Ave N at:
    • Denny Way—No left turn (6A-7P)
    • Thomas St–no right turn
    • Harrison St—No right turn
    • Republican St—No left turn
    • Mercer St—No left turn
  • Southbound Westlake Ave N at:
    • Mercer St—No right turn
    • Republican St—No left or right turn
    • Thomas St—No left or right turn
  • Near the Marriott Residence Inn and Fred Hutch
    • Minor Avenue N between Aloha Street and Valley Street—on west side remove on-street parking on west side, trim trees and install layover signs
    • Valley Street between Fairview and Minor—On north side install platform for passengers, repair road, remove on-street parking, trim trees, remove one tree and add layover signs


More bus service means there is room for hundreds of more people.
BENEFIT: Increased mobility, affordable transportation options

Dedicated transit lanes allow the streetcar and buses to bypass traffic reducing delay and making for a smoother, more predictable ride.
BENEFIT: Faster, more reliable service

Wider sidewalks and longer bus stops allow buses to board passengers without having to pull out then back into traffic. They also provide space for more buses and streetcars, shelters and real-time information kiosks.
BENEFIT: Faster, more reliable service, rider comfort, sidewalk space

Construction and Schedule

Project construction will occur January through March 2016. Traffic and parking restrictions may begin as early as  mid-March when Metro begins testing new routes and training; and to help drivers get use to new restrictions. Construction impacts include:

  • Short-term sidewalk closures and detours
  • Temporary relocation of transit stops
  • Temporary impacts to streetcar operations
  • Tree trimming and landscape relocation
  • Weekend work and possible detours
  • Noise, dust and vibration



This project is funded through voter approved Transit Proposition 1 and Move Seattle property levy.


Dec 2015 Project Fact Sheet

Dec 2015 Letter to Community  

Dec 2015 Project Media Release

Dec 2015 SEPA Checklist
Dec 2015 SEPA Checklist APPENDIX B
Dec 2105 SEPA Checklist Determination of Nonsignificance (DNS)

Oct 2015 Westlake Transit Priority Analysis Report

Related Projects

Westlake Cycle Track Project
Mercer Corridor Project
Alaskan Way Viaduct Replacement Program North End
Regional Transit Expansion: Sound Transit 3
Fairview Ave N Bridge Replacement

Project Contact

Dawn Schellenberg, Community Engagement Liaison at, or 206.684.5189


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