Seattle Tunnel Partners, the state’s contractor on the Alaskan Way Viaduct replacement, is preparing to build what will be the world’s largest deep-bore tunnel, with an outside diameter of 56 feet.
But before construction can start, the team needs to get a record of decision from the Federal Highway Administration on the final environmental impact statement, which is expected any day.
STP is led by Dragados USA and Tutor Perini Corp. The contract is worth $1.4 billion.
Work is to start in October, though actual tunneling won’t begin until mid-2013.
This year, the team will relocate utilities and install geotechnical instruments. Early next year, it will begin more visible work such as open-cut excavations and closing streets.
There are 158 buildings above or near the route of the tunnel.
The Associated Press
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