The state of Washington’s Transportation Department (DOT) invited the four contractors interested in digging the US$ 1bn tunnel along the Seattle waterfront to submit draft versions of their proposals.
The two-mile long, 54-foot diameter tunnel will be one of the largest bored tunnels on the planet. It is part of the $4.2 billion plan to replace the Alaskan Way Viaduct and downtown seawall.
The DOT will announce the best value proposals at the end of this year and a boring machine could start digging the tunnel in 2012.
