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Two-Way Mercer Street Coming Soon!

As neighbors in the South Lake Union community know well, the Seattle Department of Transportation’s Mercer Corridor Project has been under major construction since mid-2010. On August 27, following a full weekend closure of the I-5 on- and off-ramps at Mercer Street, this major roadway improvement project will reach a significant milestone: opening two-way traffic on Mercer Street between Fairview Avenue N and Dexter Avenue N.

New landscaping along the newly constructed Mercer Street

A tremendous amount of construction work and coordination has been completed in preparation for two-way Mercer Street. Take a look back at construction highlights, including replacement of a nearly 100-year old sewer line beneath 9th Avenue N, extensive undergrounding of electrical lines, water line and storm drain system upgrades, construction of the new Mercer Street lanes and rebuilding of the old lanes.

During the August 24-27 full weekend closure of the I-5 on-and off-ramps at Mercer Street, crews will complete the final pre-opening work, including concrete pavement, lane striping and signal installation. Ramp closure hours will be from Friday at 11:00 p.m. to Monday at 5:00 a.m. See the Mercer Corridor Projectwebsite for more details about the weekend closure.

New eastbound lanes of Mercer Street near Boren Avenue North

Heading west on a new road

Two-way traffic may change how you navigate to and from I-5 and through South Lake Union. Check out our map of traffic flow once two-way Mercer Street opens. Travelers can expect:

  • Three lanes of new westbound traffic that will continue straight off the Mercer Street I-5 off-ramps
  • Three lanes of eastbound Mercer Street continuing onto the I-5 on-ramps
  • New left turn lane from Mercer Street onto northbound Fairview Avenue N
  • Reopened eastbound access across Fairview Avenue N to Mercer Street for access to Eastlake and Capitol Hill
  • Access to Broad Street from Mercer Street; no access to Broad Street from Valley Street

Traveling on foot or bicycling through the area? Check out our map of pedestrian and bicycle routes.

Riding King County Metro? Due to upcoming construction on Fairview Avenue N, King County Metro Transit will temporarily reroute Routes 70/71/72/73, 83 and 309. Buses will shift their routes off of Fairview Avenue N and travel instead on Eastlake Avenue N. See the map of the King County Metro reroute on their website.

Seattle Streetcar weekend riders: The Seattle Streetcar we be closed from 11:00 p.m. on Friday, August 24 to 5:00 a.m. on Monday, August 27 to accommodate final operations work for the opening of two-way Mercer Street.

Construction continues

Following the two-way Mercer Street opening, the project begins Stage 3 of construction, including critical roadway and utility installations and severe restrictions on Fairview Avenue N. Travelers can expect:

  • One northbound travel on Fairview Avenue N between Harrison and Valley Streets
  • No access to Fairview Avenue N via Republican Street and no southbound access at the I-5 off-ramps at Mercer Street
  • One southbound lane on Fairview Avenue N from Aloha Street that connects to westbound Valley Street
  • Valley Street closed to eastbound traffic east of Terry Avenue N
  • Access maintained to Lake Union Park and businesses in Chandler’s Cove

This temporary configuration will allow crews to complete work on Fairview Avenue N and Valley Street including undergrounding electrical distribution, transmission and communication lines, replacing or relocating  water, sewer, and storm drainage systems, relocating gas lines, widening Fairview Avenue N between Republican Street and Valley Street, and installing new pavement, including on-street bike lanes. Other improvements include sidewalks, signals, lighting, signage, intelligent transportation systems, landscaping, and urban design features. Stage 3 is expected to continue through early 2013, and final completion of the east phase of the Mercer Corridor Project is expected in summer 2013.

Work on the west phase of the Mercer Corridor Project, between Dexter Avenue N and Elliott Avenue W, is expected to begin in early 2013. For questions about ongoing or future construction, contact the project team at or 206-419-5818.