Mercer Corridor Project update: work is on schedule for completion this fall

The Seattle Department of Transportation and its contractor have finished much of the construction for the Mercer Corridor Project. Construction is on schedule to continue this year with completion this fall, thanks to diligent, hard-working crews.

The final configuration will feature three lanes on Mercer Street in each direction between Fifth Avenue North and I-5, as well as new left turn lanes at Ninth Avenue North and Dexter Avenue North. The new corridor will also include a bicycle path to help connect South Lake Union and Uptown across SR 99.

In 2014, crews completed signal, travel lane and sidewalk improvements to convert Mercer and Roy streets to two-way operation between Fifth Avenue North and Queen Anne Avenue North and opened two westbound lanes on Mercer Street between Ninth Avenue North and Fifth Avenue North, providing a direct westbound connection from I-5 to Seattle Center and surrounding neighborhoods. Crews closed Broad Street at the same time to allow for the widening of Mercer Street near Dexter Avenue North.  Construction of the SR 99 bridge structure over Mercer Street is also complete.

In 2015, crews will continue to work on Mercer Street between Fifth Avenue North and Ninth Avenue North, on Dexter Avenue North between Roy and Mercer streets and on Fifth Avenue North between Mercer and Broad streets. Here’s a preview of upcoming changes you can expect to see:

Pedestrian changes

  • The west crosswalk on Mercer Street at Ninth Avenue North will re-open later this month after crews complete ADA and sidewalk improvements at the northwest corner of the intersection.
  • In the coming months, pedestrians will be routed to the north sidewalk on Mercer Street and the south sidewalk will be closed for final improvements near Dexter Avenue North. More information will be provided in advance of this change.
  • Crosswalks at the intersection of Fifth Avenue North and Harrison Street are open, although intermittent closures may occur as needed for final improvements.
  • The sidewalk on the east side of Fifth Avenue North will remain closed between Harrison and Thomas streets for the next few weeks as crews lay conduit and form and pour the new sidewalk.

Please obey detour signage to increase the safety of all travelers. Updated pedestrian and bicycle route maps are available on the project website,

Vehicular changes

  • Full closures of Taylor Avenue North between Roy and Mercer streets will be scheduled during daytime hours as needed to complete electrical work. These are currently scheduled through the week of Jan. 12.
  • A full weekend closure of Mercer Street is tentatively scheduled for early February to remove the temporary roadway along the south side of Mercer Street between the SR 99 overpass and Eighth Avenue North. Once this work is complete, the temporary curvature along Mercer Street will be removed. Look for more information in the coming weeks.
  • Daytime lane restrictions on Fifth Avenue North and Mercer Street will continue as needed.

The project team wants to thank everyone for their continued patience throughout construction in 2014. As a reminder, questions and concerns can be sent to or our 24-hour construction hotline (206)-419-5818.