The huge boring machine, named Bertha, will be used to bore the Highway 99 tunnel under downtown Seattle. It was built at a factory in Osaka and is aboard the 472-foot Jumbo Fairpartner.
The drilling machine was shipped to Seattle in pieces and it will be reassembled in a pit near the waterfront, where it will begin the year-long project to drill the two-mile tunnel.
Some of the smaller components will be unloaded onto trucks Saturday afternoon. Unloading all its pieces, which weigh about 900 tons, could take two weeks or longer.
The state Department of Transportation had planned for the ship to dock Wednesday but said Friday that bringing it into port had been delayed because they hadn't completed arrangements for unloading the ship.
The new section of Highway 99 replacing the Alaskan Way Viaduct will have a diameter of nearly 58 feet and is scheduled to open in late 2015.