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Nighttime closures of southbound SR 99 for tunnel construction start this Sunday

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Date:  Wednesday, July 18, 2012

Contact: Travis Phelps, Alaskan Way Viaduct Replacement Program (Seattle)
KaDeena Yerkan, Alaskan Way Viaduct Replacement Program, 206-805-2846, (cell) 206-795-1876 (Seattle)

SEATTLE – Drivers traveling through downtown Seattle should prepare for more nighttime closures of the southbound State Route 99 Alaskan Way Viaduct. For the next several months, the closures will give crews the space they need to reinforce a two-block section of the viaduct that sits above the route of the future SR 99 tunnel.

The reinforcement work, which began in March, is approximately 50 percent complete and must be finished before the tunnel-boring machine arrives in Seattle early next year.

Nighttime closures of southbound SR 99 will resume Sunday, July 22. All southbound lanes, from just north of the Battery Street Tunnel to the West Seattle Bridge, will close Sunday through Thursday nights. The weekly closures are expected to continue through this fall.

Nighttime closures next week

  • Sunday, July 22 – the morning of Monday, July 23 – The southbound SR 99 Alaskan Way Viaduct will be closed nightly from 10 p.m. to 5 a.m.
  • Monday, July 23 – morning of Friday, July 27 – The southbound SR 99 Alaskan Way Viaduct will be closed nightly from 9 p.m. to 5 a.m.
  • These closures are weather dependent and may be rescheduled.

WSDOT is coordinating closures of southbound SR 99 with other Seattle-area construction projects and special events at the Seattle Center and SODO stadiums. Working at night, when traffic volumes are typically lower and alternate routes are less congested, helps keep traffic moving throughout Seattle.

“Now that summer is in full swing, we don’t want to close the viaduct for an entire weekend due to summer activities, sporting events and other construction closures in the area,” said Matt Preedy, WSDOT Alaskan Way Viaduct Replacement Program deputy administrator. “Drivers can help make the closures a success if they can stay engaged and plan ahead.”

Drivers can find a list of current and upcoming viaduct closures online at:

Why so many closures?
During each closure, crews wrap a protective reinforcing fiber around the concrete beams of the viaduct’s upper and lower decks between South Washington and Columbia streets in Pioneer Square. This work is labor intensive, extremely weather dependent and much of it takes place above the southbound lanes of the viaduct.

Currently being manufactured in Japan, the tunnel-boring machine is expected to arrive in Seattle by early 2013 followed by the start of tunneling in summer 2013. The SR 99 tunnel is scheduled to open to drivers in late 2015.

Up-to-the-minute traffic information is available at and via the Washington State Department of Transportation’s voice-activated driver information line, 5-1-1.

For more information on the Alaskan Way Viaduct Replacement Program, visit

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