First Avenue South Bridge repairs will snarl traffic on key route to West Seattle; here’s what to expect

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Mike Lindblom

Seattle Times reporter

A couple of overnight repair closures this coming weekend, followed by five full days of lane reduction, will growl traffic south around the First Avenue South Bridge – a major remaining route into West Seattle.

However, the contract will wreak less havoc than the four-week project that the Washington State Department of Transportation (WSDOT) had forecast back in October before the victorious contractor presented a tighter schedule.

The southern Duwamish River crossing, which is part of State Highway 99, will close again at 9:00 p.m. Friday through 6:00 a.m. Saturday, and then closed again at 9:00 p.m. Saturday through 6:00 a.m. Sunday. Two other similar closings are scheduled for Sunday March 14th and Monday March 15th from 9:00 p.m. to 5:00 p.m.

A major traffic problem will occur on Wednesday March 10th when the First Avenue South Bridge is reduced southbound from four to two lanes – 24 hours a day through 12:00 noon on Monday, March 15. The parallel bridge to the north works normally.

WSDOT warns travelers of delays. To make matters worse, the bridge to the south was already an important detour for the drivers, while the cracked West Seattle Bridge remains closed. Traffic on industrial highways near West Seattle Bridge has tripled since the city closed that six-lane structure last March.

Massana Construction contractors of Gig Harbor will replace the bearings under the steel decks of the First Avenue South Bridge under a contract worth $ 380,455. The bearings consist of steel contact plates that rest on mortar. These allow the bridge to slide in response to normal temperature changes. But WSDOT says the 25 year old mortar is worn out.

Damaged joint bearings under the First Avenue South Bridge to the south will need to be replaced this winter.  This photo shows a gap temporarily filled with steel washers this summer.  A blue pencil was placed in the gap for the scale.  (Photo by the Washington State Department of Transportation)

Damaged joint bearings under the First Avenue South Bridge to the south will need to be replaced this winter. This photo shows a gap temporarily filled with steel washers this summer. A blue pencil was placed in the gap for the scale. (Photo by the Washington State Department of Transportation)

“We have been observing the bearings that support the bridge for a number of years,” said a statement from WSDOT project engineer Mike Askarian. “Last fall we found that they were worn to the point where they needed to be replaced. This is a challenging time for travelers with the West Seattle Bridge closed. By doing this now, you can avoid future damage to the bridge. “

Detour routes include the South Park Bridge; Interstate 5; the low bridges Tukwila International Boulevard South and East Marginal Way South, both near Boeing Access Road; or for overnight use, the West Seattle Swing Bridge, which is only open to general traffic between 9 p.m. and 5 a.m.