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Mercer Corridor Project

If you need this information translated, please call (206) 733-9990.
Si necesita traducir esta información al español, llame al (206) 733-9990.

The Mercer Corridor stretches from Interstate 5 to 5th Ave. W, and has been one of the City of Seattle’s most significant transportation challenges for over 40 years. SDOT is committed to improving the Mercer Street Corridor by 2016.

Learn more about the Mercer Corridor Project or subscribe to email alerts.

Last updated  10/06/2015

Final signal installation at Mercer St. and 9th Ave. N Oct. 12

On Monday, Oct. 12, crews will work at the intersection of Mercer St. and 9th Ave. N From 5 a.m. to 3 p.m. Oct. 12, the westbound curb lane of Mercer St. will be closed between Westlake Ave. N and 8th Ave. N. This closure will accommodate the finalization of signals and striping at this intersection. Intermittent lane closures for eastbound traffic may occur between 9 a.m. and 3 p.m. as well.

Once this work is complete, travelers can expect the following:

  • Left turns from Mercer St. onto 9th Ave. N will reopen
  • The westbound curb lane of Mercer St. will be changed from a right-only to a through and right lane. People driving in this lane have the option to continue on westbound Mercer St. or turn right onto northbound 9th Ave. N.

Full closure of Roy St. between 4th Ave. N and 5th Ave. N continues through early November

Roy St. is fully closed between 4th Ave. N and 5th Ave. N for 6 to 8 weeks as of Tuesday, Sept. 8. This closure will accommodate installation of a large stormwater detention pipe beneath Roy St. in September and October. This will help manage stormwater flows and reduce the risk of sewer overflows into Lake Union during a heavy rain. It will provide stormwater detention for the area, including the North Portal and Surface street improvements for the SR 99 Tunnel Project. Crews will work 7 days a week in October in an effort to expedite construction. Travelers through the area can expect the following:

  • Beginning Tuesday, September 8, Roy St. will be fully closed between 4th Ave. N and 5th Ave. N and remain closed for 6 to 8 weeks.
  • Local access will be maintained to the alley on the south side of Roy St. between 4th Ave. N and 5th Ave. N via eastbound Roy St. The alley will be southbound only during this closure. Please obey all closure and detour signage.
  • Vehicles and cyclists traveling on Roy St. will be detoured south to Mercer St. between 4th Ave. N and 5th Ave. N.
  • Street parking will be restricted on this block while work is completed.
  • Pedestrian access will be maintained on the south sidewalk along Roy St.

Looking ahead

  • Intermittent lane closures will continue through fall as crews complete miscellaneous improvements throughout the project area. Closures will be temporary, localized, and occur during non-peak hours, Monday through Friday.
  • Adaptive signal control is under design and expected to be installed on Mercer Street in 2016. The new system will be more responsive to traffic conditions, but will still be limited by the capacity at the I-5 on-ramps during the peak periods.

Look at what we've accomplished so far! Read more here.


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