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Tue July 16 2019

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Double-deck road tunnel opens in Seattle

4 Feb The USA’s largest double-deck highway tunnel has opened after nearly two decades of planning and construction, including two years of repairs to the TBM.

Transportation secretary Roger Millar spoke at the opening
Transportation secretary Roger Millar spoke at the opening

The SR99 tunnel in Seattle, Washington, is two miles long and carries two traffic lanes plus a safety shoulder in each direction. It replaces the seismically vulnerable Alaskan Way Viaduct.

It was built using a record-breaking tunnel boring machine, Bertha, which was out of action for two years while repairs took place (link opens in new tab).

Celebratory events were held this weekend.

“This is a game changer,” said transportation secretary Roger Millar. “Our number one goal was to remove a vulnerable structure from our highway system. Along the way we reshaped a major transportation corridor that is a key component of the mutlimodal transportation system we and are partners are building for the Puget Sound region.”

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