Feb 15, 2008 9:05 pm US/Eastern
An Exclusive Look At Pittsburgh's 'Big Dig'
NORTH SHORE (KDKA) ―
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As the machine cuts through the ground, crews are putting 4-foot segments of the tunnel behind it.
KDKA
It's a $435 million project to connect downtown Pittsburgh to the North Shore.
But how do you dig a tunnel under a river?
KDKA's John Shumway takes an exclusive look at the North Shore Connector project.
As the machine cuts through the ground, crews are putting 4-foot segments of the tunnel behind it. It then pushes off of those segments to keep it moving forward.
"The learning curve is kinda starting to come out a little bit. I see they're starting to build that tunnel sphere," Nick Fossum, lead tunnel inspector, said. "But I mean when we first started it would have taken them an hour and a half to two hours to set a ring. We did it this last ring in 47 minutes."
With the night shift on its way to work, the day crew was just finishing its fourth ring.
The drill stops about every four feet to install another of the seven-segment rings that make up the finished tunnel wall.
So far, the crews have for the most part only been held back by their own learning curve.
Rebecca Vettorel, of McDonald, is at the helm.
"We're digging away. We're in production now," she tells KDKA.
Shumway: "Is it what you thought it would be?"
Vettorel: "I really didn't know what to expect, but it's different - it really is. And going back to the back of the machine and looking forward you can see how much we've progressed already and I'm looking forward to what it's going to be like under the river and out on the other side."
Crews are working two 10-hour shifts with the other four hours for maintenance. So far, the only problems they've had are very minor mechanical problems that haven't delayed them for long.
They're on schedule to end up on the other side of the river by this summer.
(© MMIX, CBS Broadcasting Inc. All Rights Reserved.)
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