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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 Avenue 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 04/21/2014

Partial closure of the intersection of 5th Ave. N at Mercer St. scheduled for the weekend of April 26-28

SDOT advises travelers of the partial closure of the intersection of 5th Ave. N and Mercer St. scheduled for Saturday, April 26 to Monday, April 28.

Beginning the morning of Saturday, April 26 at 4:00 a.m. through Monday, April 28 at 5:00 a.m., the intersection of 5th Ave. N and Mercer St. will be partially closed to traffic to accommodate roadway excavation and preparatory work for concrete paving. During the closure:

  • Travelers heading east on Mercer St. towards I-5 will be detoured onto southbound 5th Ave. N to Harrison St. to eastbound Broad St. to reconnect with Mercer St.
  • Southbound 5th Ave. N will be fully closed to traffic between Roy and Mercer streets. Travelers heading south on 5th Ave. N will be detoured to westbound Roy St. and 4th Ave. N in order to reconnect with 5th Ave. N via eastbound Mercer St.
  • Travelers heading north on 5th Ave. N will be detoured at Republican St. to continue north on 4th Ave. N toward Seattle Center and the Queen Anne neighborhood.
  • Local access to businesses and properties will be maintained at all times.
  • Pedestrians will be detoured and advanced signage will be posted.
  • Travelers heading toward Queen Anne and Seattle Center from I-5 and Downtown should use westbound Broad St., Denny Way, and northbound 1st Ave. N as an alternate route.
  • Mercer St. between Taylor Ave. N and I-5, Broad St., Dexter Ave. N, SR 99 and the I-5 on- and off-ramps at Mercer St. will remain open during the weekend work.

Please note that work is weather dependent and may be cancelled and rescheduled for later dates if inclement weather occurs.

Early warning signs will be available in advance of all detours.

Weekend detour map for April 26-28

Mercer and Roy streets transition to two-way traffic this spring; Broad St. closes this June

SDOT announces a major milestone for the Mercer Corridor Project with two-way traffic opening on Mercer St. between 1st Ave. N and 9th Ave. N and on Roy St. between Queen Anne Ave. N and 5th Ave. N this spring.

Construction to extend two-way Mercer St. from 9th Ave. N to 1st Ave. N in Uptown began in April 2013. Over the past year, crews have completed demolition and substantial reconstruction of the SR 99 bridge over Mercer St., relocated utilities between 5th Ave. N and 9th Ave. N, and completed street light upgrades, signal installations and pedestrian improvements between Queen Anne Ave. N and 5th Ave. N.

Beginning in late April, travelers will experience major corridor changes as crews begin converting Mercer St., Roy St. and Queen Anne Ave. N to two-way traffic. The transition to two-way traffic will occur in three phases:

  • The first phase will include shifting the two eastbound Mercer St. traffic lanes onto their permanent location on the south side of the roadway between 1st Ave. N and 5th Ave. N and installing channelization for the new westbound traffic lanes. 
  • At the end of this initial phase, traffic signals will be activated and Mercer St. will be opened for two-way traffic starting at 1st Ave. N and working toward 5th Ave. N over a period of several days.
  • The second phase will include converting Roy St. between Queen Anne Ave. N and 5th Ave. N to two-way traffic. During this conversion, westbound Roy St. will be reduced to one lane while final channelization is put into place. Signals will be activated for two-way traffic on Roy St. starting at 5th Ave. N and working toward Queen Anne Ave. N over a period of several days.
  • The final phase of the transition will include opening Mercer St. to two-way traffic between 5th Ave. N and 9th Ave. N as well as the permanent closure of Broad St. in late May or early June. The closure of Broad St. allows for additional space to widen Mercer St. to the south at Dexter Ave. N and continue work associated with the Alaskan Way Viaduct Replacement Project.

Click here for maps detailing each phase of the traffic switch

Throughout and after the roadway transition, construction impacts will be monitored and will include:

  • Monitoring traffic flow and adjust signal timing as conditions change throughout the corridor
  • Uniformed police officers stationed at key intersections to facilitate traffic flow
  • Additional signage and alternate route information will be available in advance

After opening Mercer St. to two-way traffic between 1st Ave. N and 9th Ave. N, construction will continue on Mercer St. between 5th Ave. N and 9th Ave. N, including the intersection of Mercer St. and Dexter Ave. N through mid-2015. The final configuration of Mercer St. between 5th Ave. N and 9th Ave. N will feature three lanes of traffic in each direction, widened sidewalks, and a bicycle path on the north side of Mercer St. between Dexter Ave. N and 5th Ave. N. 

Intermittent lane closures on Mercer St. through June

Eastbound Mercer St. between 3rd Ave. N and Dexter Ave. N will have intermittent lane closures during off-peak travel times between 9:00 a.m. and 3:00 p.m. to accommodate construction activities within the work zone. One lane on eastbound Mercer St. will remain open at all times.

Pedestrian improvement work on the south side of Mercer St. this spring

This spring, crews will continue to make improvements to utilities, sidewalks, curbs and ADA ramps along the south side of Mercer St. as part of the Mercer Corridor Project. Updated detour information will become available as work conditions change.

Travelers can expect the following impacts:

  • Crosswalks adjacent to the work zones will be temporarily closed
  • Pedestrian routes will be detoured and advanced signage will be posted
  • Parking adjacent to the work zone along the south side of Mercer St. will be restricted
  • Local access to businesses and adjacent properties will be maintained at all times
  • Work hours will be approximately 7:30 a.m. to 5:00 p.m.

Current Traffic Configuration

Travelers can expect the following changes when traveling through to the corridor during construction:

  • Mercer St. reduced to two eastbound lanes between 2nd Ave. N and 9th Ave. N.
  • Local access maintained at Taylor Ave. N.
  • The sidewalk on the south side of Mercer St. is closed between 5th Ave. N and Dexter Ave. N to facilitate construction activities on the south side of the roadway. The sidewalk on the north side of Mercer St. will remain open on a temporary asphalt path.
  • Broad St. open to two-way traffic.
  • SR 99 traffic shifted to the east side of the roadway between Valley and Harrison streets. Two lanes of SR 99 in each direction will remain open.
  • The northbound SR 99 off-ramp to Mercer St. is permanently closed. A new signalized intersection at Republican St. and Dexter Ave. N is available for northbound SR 99 traffic to reach South Lake Union.
  • Due to the re-opening of Broad St. to two-way traffic, left turns from eastbound and westbound Mercer St. onto 9th Ave. N will be restricted in order to facilitate traffic flow on Mercer St. Travelers heading north towards Westlake and Fremont should use Dexter Ave. N to reach their destinations.

Lane reductions on Mercer St. will continue throughout the West Phase of the Mercer Corridor Project, which is anticipated to be completed in mid-2015. Construction of this $95 million project will take approximately 2.5 years.

Click here to view detour maps.


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