The Road to Two-Way Mercer Street

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. Coming in late summer or early fall of 2012, this major roadway improvement project will reach a huge milestone: the opening of two-way traffic on Mercer Street between Fairview Avenue N and Dexter Avenue N. A tremendous amount of construction work and coordination has been completed in preparation for this milestone. Major roadway and utility improvements have been completed already, including the replacement of a nearly 100-year old line beneath 9th Avenue N, extensive undergrounding of electrical utility lines, water system and storm drain system replacements, and the construction of the new lanes of Mercer Street north of the original lanes, along with sidewalks along the north side of Mercer Street.

Crews are currently working to complete construction of underground utilities and then rebuild the old lanes of Mercer Street in preparation for two-way traffic. Once the two-way traffic section of Mercer Street is open, drivers exiting I-5 will have the option to continue straight westbound and avoid existing circuitous one-way routing onto Fairview Avenue N and Valley Street. Route maps for vehicles, bicyclists and pedestrians will be provided prior to this major traffic change.

Mercer construction

In addition to traffic flow changes, travelers through the area will continue to see other improvements between today and project completion of the east phase of construction in mid-2013. The Mercer Corridor Project incorporates improved signal timing, new pavement and sidewalks, as well as other innovative design and construction methods that have earned the project the highest score of any “Greenroads” pilot project, which is a certification process similar to LEED certification for buildings.

For a preview of what comes after two-way Mercer Street milestone, check out Stages 3 and 4 of the project schedule. Work on the west phase of the project, between 9th Avenue N and Elliott Avenue W, is planned to begin in 2013. For questions about the Mercer Corridor Project construction, contact the project team at or 206-419-5818.