The Seattle Department of Transportation (SDOT) advises travelers of the upcoming closure of northbound SR 99 at Mercer Street, and of Mercer Street between Fifth Avenue North and Dexter Avenue North, during the weekend of Sept. 6 – 7, for construction activities associated with the West Phase of the Mercer Corridor Project.

Beginning Friday evening through Saturday afternoon, Mercer Corridor Project crews will set girders necessary for rebuilding the east half of the SR 99 bridge over Mercer Street. Northbound SR 99 and Mercer Street will be fully closed to traffic beginning Friday, Sept. 6 at 11 p.m. through Saturday, Sept. 7 at 2 p.m. During the closure:

•  Northbound SR 99 will be fully closed between Western Avenue and Valley Street. Traffic traveling through Seattle via SR 99 will be directed to I-5 south of Seattle at East Marginal Way and Spokane Street. More information about alternate routes during construction may be found at: http://www.seattle.gov/transportation/mercercorridor.htm.
• Mercer Street will be fully closed to traffic between Fifth Avenue North and Dexter Avenue North. Traffic heading east towards I-5 will be detoured to Harrison and Broad streets at Fifth Avenue North and will reconnect to Mercer Street at Ninth Avenue North to continue east.
• No pedestrian access will be allowed on Mercer Street between Fifth Avenue North and Dexter Avenue North during the weekend closure. Pedestrians will need to use the sidewalk on the north side of Broad Street to cross SR 99.
• Southbound SR 99, Broad Street, and the I-5 on- and off-ramps at Mercer Street, will remain open during the work.

Early warning signs will be available in advance of the northbound SR 99 lane restrictions. Travelers can expect significant traffic and delays and should plan ahead and use alternate routes.