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I-485, Unusual Interchanges Should Be Finished By Dec. 2014

Interstate-485 will finally become a complete loop next year, and some northern sections will feature unusual interchanges. State and federal transportation officials gave that update Tuesday while standing at the edge of one of the interchanges.

The rain didn't keep Davis Diggs and Gary Eudy from showing off how their babies are almost all grown up.

"We're standing at the border between Gary's project and my interchange," Diggs said. On one side, there's concrete road, and on the other, paved dirt.

The concrete is part of Diggs' interchange. It's where I-85 and I-485 come together in northeast Charlotte.

"How much of my life has been spent out here?" Diggs said with a laugh. "I wake up in the middle of the night in a cold sweat, no, I'm kidding."

But he said the project has taken up most of his time the last two years. It's called a turbine interchange, the first of its kind in North Carolina. It's cheaper than the standard interchange because it uses smaller, simpler bridges.

"You don't have nearly as much steel," he said. "You don't have nearly as much structure to build the stacks of bridges, and they're easier to maintain over the life of the project as well."

It's designed so that cars turning left will circle around a central bridge to keep traffic flowing. (You know how water moves around a whirlpool? That's kind of how traffic will move, at least if you're looking at it from above.)

Gary Eudy's project, on the other hand, begins at the paved dirt and stretches for about six miles. He's in charge of the last leg of I-485.

"I've been with the state of North Carolina about 34 years, and about 30 of it, I've been on and off the I-485 section," Eudy said.

By that, he means he's worked on a variety of sections since the state started building the loop. Now he's finishing it. 

It'll have its own innovative interchanges called a diverging diamond and a split diamond.

"The diverging diamond interchange at Mallard Creek has been proven," he said.

In Missouri, that kind of interchange has dramatically reduced traffic in a few areas, according to transportation officials there. It works by switching drivers onto the left side of the road if they exit and turn left across the overpass.

"And the split diamond interchange at the Prosperity Village area, that's just nothing but two service roads on each side of the interstate connected with roundabouts," Eudy said.

All the new interchanges will save the state money. Eudy and Diggs said it's more than $50 million cheaper to build their interchanges than three standard ones.

That kind of innovation and cost-savings brought Federal Highway Administrator Victor Mendez to the rainy construction site Tuesday.

"I think this is important for me to be able to highlight this when I go and visit other states to say: 'Hey, you know what, come check out North Carolina. They're doing some really innovative things that might help you out.'" 

The projects are on schedule to be finished by December 2014.