SR 99 from south Seattle to Valley St. will be closed for four days as crews demolish a bridge and build a new highway section over the now-closed Broad St. (Riley Elliott/MyNorthwest.com)

SR 99 closure to cause big Seattle backups for next 4 days

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Trying to get through Seattle this weekend? Good luck. The Washington State Department of Transportation is closing State Route 99 for four days of construction, and with other changes through the Mercer Mess, backups are inevitable.

Starting Thursday morning, Mercer Street will be shifted south to allow for demolition of the bridge over Broad Street and utility work. The Seattle Department of Transportation says that will last a year.

The SR 99 closure is set to begin at 10 p.m. Friday, when crews shut down the highway in both directions, from Spokane Street south of downtown up to Valley St. in South Lake Union.

For Seahawks fans leaving Friday night's game, WSDOT will keep northbound traffic flowing from CenturyLink Field until the crowds clear.

It's just the latest stage in the ongoing work to replace the Alaskan Way Viaduct with a tunnel beneath downtown.

The section of SR 99 between Spokane Street and the south end of the Battery Street Tunnel will reopen just before the Monday morning commute, but the highway will remain closed through the tunnel to Valley Street until 5 a.m. Wednesday, Aug. 27, WSDOT says.

Crews will demolish the SR 99 bridge that crosses over the now-closed Broad Street that used to connect South Lake Union with Seattle Center because it's now in the wrong place. They'll then fill in Broad Street and repave SR 99, all by next Wednesday.

The new section of the highway will become part of the permanent connection between the SR 99 tunnel's north portal and Aurora Avenue North.

WSDOT says drivers should brace for big backups on I-5 getting into the city from both the north and south. Spokesman for WSDOT, David Sowers, says while it's a major headache, the alternative was far worse.

"Instead of a bunch of closures spread out over weeks and months, we're trying to cram it all into these four days," Sowers says.

Metro Transit is warning bus riders could be particularly hard hit by the closure. Seventeen different routes and hundreds of thousands of riders will be affected.

Says Metro's Matt Hansen, "Our key message for our customers is be informed, be flexible and be patient."

Josh Kerns, MyNorthwest.com
Josh Kerns is an award winning reporter/anchor and host of KIRO Radio's Seattle Sounds (Sunday afternoons 5-6p) and a digital content producer for MyNorthwest.com.
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