The ship was greeted in Elliott Bay by a fire boat spraying water.
The $80 million machine called Bertha was built at a factory in Osaka. Its 41 pieces will be reassembled in a pit to begin the year-long dig to create a two-mile tunnel under downtown Seattle.
The new section of Highway 99 replacing the Alaskan Way Viaduct will have a diameter of nearly 58 feet.
More Northwest Headlines
Seattle officer fired for obstructing investigation Alaska hired consultants ahead of Obama visit State ferries selling 9 generators it bought but never used US judge declines to undo government order on green cards Oregon gunman killed himself after police shot him Portland to recognize Indigenous Peoples Day Threat causes Southern Oregon University to cancel classes EPA rushed to judgment in blocking Alaskan gold mine, report suggests
Our new comment system is not supported in IE 7. Please upgrade your browser here.