How do they do it? Building the downtown bridge - wave3.com-Louisville News, Weather & Sports

How do they do it? Building the downtown bridge

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A pier on the Indiana side of the Ohio River for the new downtown bridge. A pier on the Indiana side of the Ohio River for the new downtown bridge.
Andy Barber Andy Barber
Joel Halterman Joel Halterman
Max Rowland Max Rowland
Two of the steel casings that will be used to build the new downtown bridge. Two of the steel casings that will be used to build the new downtown bridge.

LOUISVILLE, KY (WAVE) - It's a real-life "How Stuff Works" happening right in front of our eyes in the Ohio River. The construction of a new bridge downtown meant to carry drivers across the river for the next hundred years is a mind-boggling task for many of us.

The best way to understand how it is to get on the river itself and get up close, just a few feet away from the bridge's foundation: five piers that will be built in the middle of the water.  Four additional piers will support the bridge on land.

"So we're putting these in rock so you have a good solid foundation from which to build your bridge," said Andy Barber, project manager with the Kentucky Transportation Cabinet.

Giant steel casings go down anywhere from 30 to 80 feet to the limestone below the river. They are then forced another 30 feet into the rock.

"It's a big vibrating hammer that shakes the casings and pushes it down into the rock," said Joel Halterman, project manager with Walsh Construction.

Then, a drill hollows out the inside of the casings and workers put reinforcing steel bars inside.

"Then we'll pour concrete and fill it up with concrete so the steel casing acts as a form to hold the concrete in," Halterman said.

"When we pour the casings though, they're full of water," said Max Rowland, another project manager from Walsh Construction. "We start pouring concrete from the bottom and work our way up and the concrete being filled from the bottom up displaces the water."

But this is a little more complicated than pouring concrete for, say, your driveway. There's so much of it that when it starts to harden, Rowland says it creates enough heat that it could cause the concrete to crack.

"What that means is we actually have to put special pipes embedded in that to pump water through to keep it cool," Rowland said.

That's the same technology that workers building the Hoover Dam invented way back in the 1930s. Other parts of building this modern, Ohio River bridge are much more advanced.

"Our methods don't involve getting any of our workers down inside the casings," said Halterman. "It's all done with equipment that excavates it out and we don't ever have to go inside of the casings."

Workers will start pouring concrete in the first pier later this month but it won't be next year until you really start to see the towers soar out of the water.

They say that the limestone in the riverbed is a little harder than they would have liked. At its most difficult, the drill can only go about four inches an hour. However, project managers say construction on the Downtown Bridge is still on schedule.

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