Brenda the tunnel boring machine battles Bertha's bad rap


by MEG COYLE / KING 5 News

Bio | Email | Follow: @MegCoyleKING

Posted on May 1, 2014 at 8:52 AM

Updated Thursday, May 1 at 8:55 AM

SEATTLE -- Move over, Bertha. Brenda is about to bust a move. The tunnel boring machine is heading south in June on a journey from Northgate to Husky Stadium. But given all the problems with big sis Bertha, many wonder if Brenda is up to the challenge.

Sound Transit insists she is as ready as she can be. Crews have conducted geotech testing and know about as much as they can know heading into the project. In fact, Brenda has been quietly making inroads on the light rail project for some time now. 

Brenda is made by the same manufacturer as Bertha but that, says Sound Transit, is where the similarities end. For starters, Bertha is about three times the size of her little sister. There are also different contractors involved. The Highway 99 tunnel is a state project, while the light rail project belongs to Sound Transit. Bertha's digging a tunnel for cars, and Brenda bores tunnels for light rail trains.

In fact, she's already dug twice, from Capitol Hill under I-5 to Convention Place.

But with about 300 feet of trailing gear, Brenda must also carry the burden of her big sister's sullied reputation.

"They're very different jobs. And we feel we've done everything we can to be ready to go. And with the track record we've had with this contractor and with this machine, which is a standard size for transit tunnels that we've dealt with, we feel like we're in a good position to get going," said Sound Transit Spokesman Bruce Gray.

Brenda heads south in June. And then in September, another drill will be moved into place to begin work on the northbound tube just a few yards away. 

While Brenda didn't get stuck like Bertha, Brenda's previous dig wasn't exactly a smooth ride. She did make some noise along the way under the Montlake neighborhood. So on this dig, Sound Transit has a plan: "We're hauling supplies including tunnel liners. Those are going to be brought in on rubber-tired vehicles so you won't have any issues with vibrations or noise as the machine is mining underneath these neighborhoods," Gray said. 

On this next mission, Brenda will travel under several neighborhoods including Roosevelt and the University of Washington before reaching Husky Stadium in about two years.