Tunnel · United States

What is the contract value of Mount Baker Tunnel?

The Mount Baker Tunnel (Mount Baker Ridge Tunnel) in Seattle is the group of tunnels carrying Interstate 90 and Link light rail's 2 Line under the Mount Baker neighbourhood, whose new tunnel, bored north of the original 1940 twin tunnels, is 1,500 ft (about 460 m) long with a 63.5 ft clear interior diameter and was the world's largest-diameter soft-ground tunnel, opened in June 1989. Transportation Research Record 1150 (1987) says its boring contract was awarded to Guy F. Atkinson Construction in October 1982 for USD 38.3 million out of 18 bids, work ran from January 1983 to May 1986, and the tunnel is one part of the overall I-90 improvement from Seattle to Bellevue estimated at more than USD 1 billion, the figure used as the earlier snapshot answer.