Bertha, born in Japan, is moving to Seattle. The world’s largest-diameter tunneling machine—57.3 ft—will soon be on a ship bound for the Pacific Northwest’s Eilliott Bay, set for reassembling in Seattle starting in April.
As part of the overall $3.14 billion project to completely eliminate the Alaskan Way Viaduct with a new State Route 99, crews must bore a 1.7-mile tunnel beneath downtown Seattle. And they will use the 326-ft-long Bertha to do it.
Constructed in Osaka, Japan, by Hitachi Zosen Corporation, the five-story-tall, $80 million machine must first be disassembled and loaded onto a ship in 41 pieces to make its way to Seattle.
Once in Washington, the machine will be reassembled and launched into a tunneling pit, where Bertha will start her dirt-chewing mission, one you can follow on Twitter at @BerthaDigsSR99.
Crews have the tunnel-launch pit about 80 percent complete and have strengthened the soil around the area. Once the 7,000-ton Bertha arrives, crews will transport the components a few hundred yards to the 80-ft-deep pit, where she will be reassembled, tested and launched this summer with a late 2015 tunnel opening in mind.
Plans have Bertha leaving for Seattle soon, expected to arrive by the end of the month. The 41 pieces—the largest individual component weighs about 900 tons—will all travel the Pacific aboard the Jumbo Fairpartner.
“While we have a lot of work to do once Bertha arrives, we can’t wait to introduce her to the people of Washington,” says Linea Laird, Washington State Dept. of Transportation’s Alaskan Way Viaduct Replacement Project administrator.
Joint venture Seattle Tunnel Partners (Dragados USA and Tutor Perini Corp.) will operate Bertha in Seattle, but don’t officially take ownership of her until she has tunneled 1,000 feet without any issues. Extensive tests in Japan revealed only one needed fix to the main drive unit.
Bertha, named after Bertha Knight Landes, the first woman to ever lead a major American city as mayor of Seattle in 1926, must now wow the locals awaiting her arrival. And her sheer size won’t be the proving ground. Soon the digging will start.
Tim Newcomb is Engineering News-Record’s Pacific Northwest contributor. He has also written for TIME, Popular Mechanics, Popular Science and more. You can follow him on Twitter at @tdnewcomb or visit his website here.
