Skanska in $1.4 billion deal to replace vulnerable Seattle bridge

Plan view of the future Roanoke Lid, looking southeast Plan view of the future Roanoke Lid, looking southeast (Image: Washington State Department of Transportation)

Skanska has won a deal for US$1.4 billion with the Washington State Department of Transportation (WSDOT) to replace the Portage Bay Bridge in Seattle, Washington.

The Portage Bay Bridge and Roanoke Lid Project replaces the aging Portage Bay Bridge, which was built in the 1960s, with a seismically resilient structure.

Supported by hollow concrete columns, the existing four-lane bridge could collapse in a severe earthquake, according to WSDOT.

The project also includes improved bus/carpool travel and an extension of the SR 250 Trail. It also builds a landscaped lid between Seattle’s Roanoke Park and North Capital Hill neighbourhoods.

WSDOT opened bids for the project in September 2023, before announcing Skanska’s $1.4 billion proposal as having the Apparent Best Value (ABV), which exceeded its engineer’s estimate.

It has awarded Skanska the project although the budget requires it to seek cost reduction opportunities and issue a report on its efforts by December 2024.

Construction is planned to commence in August 2024 with anticipated completion in 2031.

The Portage Bay Bridge and Roanoke Lid Project is part of a larger programme to reconstruct the SR 520 corridor from I-405 in Bellevue to I-5 in Seattle. When the corridor’s reconstruction is complete in the late 2020s, all of SR 520’s major bridges will be replaced by seismically stronger structures.

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