How to plan ahead for huge weekend traffic delays

by: Alexis Smith Updated:

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SEATTLE —

Seattle drivers can expect extra congestion and long delays this weekend with closures for two separate projects affecting State Route 99.

The closures begin Friday at 11 p.m. Both directions of State Route 99 will close from Valley Street to the south end of the Battery Street Tunnel for work on the West Phase of the Mercer Corridor Project.

Crews plan to install an underground waterline and make storm-water improvements. Lanes should reopen in time for the Monday morning commute at 5 a.m.

The State Department of Transportation has also chosen this weekend for the semi-annual Alaskan Way Viaduct inspection. That also will shut down State Route 99 from the Battery Street Tunnel to Spokane Street from 5 a.m. to 6 p.m. Saturday and from 6 a.m. to 6 p.m. Sunday.

Traffic will be shifted to Interstate 5 during the closures. Southbound drivers north of Seattle will exit just before Green Lake at 85th Street and head east to southbound I-5. Those coming in from the south will be directed to northbound I-5 at East Marginal Way and Spokane Street.

Broad Street, Mercer Street, and the Mercer I-5 on and off ramps will remain open all weekend.

Department of Transportation staff said they scheduled both projects for this weekend to avoid backups on multiple weekends.