West Seattle Bridge repair job ready for bidders

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The Seattle Department of Transportation (SDOT) has begun recruiting construction companies to strengthen the cracked West Seattle Bridge, which is slated to reopen to traffic in mid-2022.

City engineers estimate the value of the contract in bidding documents released Wednesday morning at $ 48 million. The winning team will create a final structural design and hire subcontractors before work on the concrete structure resumes in November.

The starting gun will be fired as Seattle nears the anniversary of the emergency closure of the six-lane span on March 23, when bridge engineers concluded that accelerating cracks could lead to a collapse if traffic continues. The damage began seven years earlier with tiny hairline cracks that were only perceived by the city as a security threat in early 2020.

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Next winter, contractors will pull tons of steel cables lengthways through the 140-foot central span and the two adjacent side spans to compress and secure the 37-year-old concrete. This process is known as preload.

SDOT says it has reached 30% design, a general milestone for public works projects. In a relatively new contract method, the winning team will complete all of the engineering and then propose a price to carry out repairs. This is to help the city and builders find potential problems before heavy construction begins, thereby reducing costly change orders.

The crews will also inject mortar to strengthen the ground around Pier 18, a foundation at the east end. This will improve the bridge’s ability to withstand an earthquake, said Heather Marx, director of urban mobility.

The new contractor will also put in carbon fiber wrap to reinforce the lower swing bridge on Spokane Street, which has less severe structural cracks and which passed a heavy load test in spring 2020. This crossing is now being penalized by diverted transit buses. Hundreds of truck journeys will soon begin as the Port of Seattle’s vast Terminal 5, west of Duwamish Waterway, reopens.

The lower bridge may also need to be repaired on the pivoting locking systems that control the pivoting double bridge spans when boats pass through.

Once the high-rise repairs are complete, traffic would gradually resume through June 2022 as SDOT watches the bridge react, Marx said.

It is possible that repair work on the swing bridge will result in both bridges being closed at the same time. Even trucks and buses would have to make the five-mile detour. However, SDOT assumes these full corridor closures will be limited to certain weekends and holidays, Marx said.

Before it was shut down, the viaduct served more than 100,000 vehicles and 20,000 transit drivers a day as the busiest crossing in city property.

Most travelers have to drive up to eight kilometers on industrial and residential roads. The low swing bridge is restricted to transit, trucks, emergency vehicles, and a small number of passport holders such as maritime workers.

Since camera surveillance began in January, the daily crossings on the swing bridge have decreased by more than 2,000 vehicles.

Diane Sosne, President of Service Employees International Union Healthcare Local 1199NW, suggests additional IDs such as: For example, on-call nurses who need to get to work within 30 minutes – one of many ID requests from the community. SDOT anticipates truck traffic will fill the low bridge early next year and is reluctant to relax access rules now.

SDOT has a total budget of $ 175 million for work related to the West Seattle Bridge corridor. This includes not only the repair contract and contingent liabilities, but also the stabilization of the bridge in the last year, the engineering for the investigation of the bridge and a future replacement bridge, repairs of sidewalks and new traffic signals on the diversion routes as well as non-moving alternatives.

Marx said the city has identified $ 124 million to be repaid through future property taxes, along with a federal grant of $ 15.9 million and $ 9 million from a voter-approved transit sales tax. State lawmakers are considering a $ 25 million contribution if a huge transportation package comes by Olympia.