South Park Bridge might close by end of June

The deteriorating South Park Bridge, a key link across the Duwamish River, will close June 30 unless an upcoming study shows it is safe for continued use, King County Executive Dow Constantine said Wednesday.

County transportation officials have warned for years the crumbling, 78-year-old drawbridge would have to close in 2010 if they couldn't find money to replace it. The county budget provides funding to operate the bridge only through June 30.

If an engineering study by the firm HNTB shows the bridge can be operated safely after that date, Constantine said, he will ask the Metropolitan King County Council for money to keep it open the rest of the year.

The bridge shuttles 20,000 cars and trucks across the river each day in an area of factories, warehouses and the residential neighborhoods of South Park, Georgetown and Boulevard Park. If it is closed, much of that traffic would be diverted to the First Avenue South Bridge.

But, Constantine said, "There are no operating funds available and a study may show its useful life is over. I can't in good conscience tell them to operate a bridge if it's unsafe."

County Road Services manager Linda Dougherty said she expects the study to give "a very current, accurate understanding of the condition of the bridge" by May 1. If the bridge were kept open, she said, it would cost $150,000 to operate it for the second half of the year, and that cost could be offset by not filling vacant staff positions in her division.

A 2006 assessment of the bridge showed that one of its piers isn't anchored in stable soil, both piers were built with substandard concrete, and shifting of the piers could leave the bridge stuck in the closed position. Dougherty said the study showed one side could collapse if an earthquake struck when the bridge was in the open position.

The Federal Highway Administration has given the bridge one of its worst safety rankings in the state, significantly worse than Seattle's earthquake-damaged Alaskan Way Viaduct.

King County is legally responsible for the bridge but doesn't have money to build a replacement, which the county estimates would cost $123 million. The bridge's northern end is in Tukwila near Boeing Field and its southern terminus rests in an unincorporated strip known as "the sliver by the river."

The federal government last month rejected King County's request for $99 million in stimulus dollars to pay most of the replacement cost for the bridge. Instead $30 million was awarded for a competing Seattle project to transform one-way Mercer Street into a landscaped, two-way boulevard.

Constantine vowed to continue to seek support from the federal and state governments to build a new bridge, saying the project would cost more than the county's annual budget for maintaining 1,800 miles of roads and 185 bridges.

"I'm frustrated, but undaunted," he said.

A portion of the cost of a new bridge could come from a transportation-benefit district that was created in January by the County Council with authority from the Legislature to impose a vehicle-license fee of up to $20 in unincorporated parts of the county. That source, paying debt service on bonds, could raise $30 million for the bridge.

Keith Ervin: 206-464-2105 or kervin@seattletimes.com