Has Big Bertha met her match?
She has, at least for the time being. The world’s largest tunnel-boring machine was recently brought to a halt 60 feet beneath the streets of Seattle, Washington when it hit an unknown object and could move no farther, reported KOMOnews.com.
The five-story head of the machine was completely brought to a halt by the object and, erring on the side of caution, Washington State Department of Transportation officials decided to shut her down until they could figure out what was in the way.
“We’re being really cautious,” WSDOT’s KaDeena Yerkan told CBS News. “We want to make sure we don’t damage this $80 million machine.”
Officials say it could take up to two weeks to figure out just what is obstructing the machine. It could be a large boulder. “We’ve got a general idea of how many boulders there might be and what size they might be,” deputy project manager Gregory Hauser told CBS. “But, there’s no guarantee that there couldn’t be a 20-footer sitting in the way.”
Whatever the mystery object is, it’s strong. Bertha, as seen above, eats through walls with ease.
Bertha has dug 1,000 feet for the Washington State Route 99 tunnel beneath downtown Seattle. The new tunnel will carry a double-deck highway and stretch 1.7 miles. It will replace the SR 99 Alaskan Way Viaduct. Replacing the viaduct will cost a total of $3.1 billion. Digging the tunnel alone will cost $2 billion.
Bertha is designed to drill 30 feet per day and installs concrete panels as she goes.
The machine arrived in Seattle in April and was lowered into position in June.
WSDOT officials aren’t sure how long Bertha will remain stopped but say it’s too early to tell if the setback will delay the opening of the tunnel slated for 2015.