SEATTLE – Drivers who use State Route 99, including the Alaskan Way Viaduct, to get through Seattle need to plan for five days of closures starting Friday. It's the latest part of the project to replace the viaduct with a tunnel.

The Broad Street Bridge is being demolished because it's now in the wrong place.

Starting at 10 p.m. on Friday through the following Monday at 5 a.m., Highway 99 will be shut down from Spokane street south of downtown to Valley St. in the South Lake union neighborhood.

Yes, there is a Seahawks preseason game that Friday night. Part of the northbound lanes will be left open for a few more hours to help fans get out.

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On that Monday and Tuesday, the viaduct will be re-opened as far north as Western Avenue, but 99 will remain closed through the Battery Street tunnel to Valley Street until 5 a.m. Wednesday.

If there's a bad accident on Interstate 5 during all this, brace yourself.

"If you can't use north or southbound 99, you're going to see surface street gridlock," said KING 5 Traffic Reporter Tracy Taylor. "People are going to exit off of I-5 and they're going to try and find their way around. We're going to see absolute gridlock downtown if we're not prepared for that."

So you may want to make that a long weekend, work from home or leave for work early.

KING 5's Glenn Farley contributed to this report

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