CARY, N.C. — U.S. 1 between Raleigh and Cary is known as one of the Triangle's top traffic trouble spots. Many drivers have complained about the rough ride on the construction zone's new concrete pavement.

But now, the Department of Transportation hopes diamonds will help smooth things out. Or in this case, it's a diamond-tipped 4-foot-wide cutter, spewing concrete dust on heavy equipment. The machine generates so much heat that it needs a water-cooling support staff.

"They're grinding off the top surface of the concrete pavement, and what it's going to do is ensure a smoother, quieter ride than what you would typically see on a concrete roadway," said DOT engineer Cadmus Capehart.

On what will be the southbound lanes of U.S. 1 just south of Walnut Street in Cary, the diamond-cutting crew has already come through and milled down a portion of the road. The difference in the road is obvious, and is designed to give motorists a smoother ride.

"To my knowledge, this is the first time we've done a 100 percent diamond grind job in North Carolina," said Capehart.

The project started back in January 2005, and drivers have been weaving through the construction zone ever since. Motorists are now asking when the project will be completed.

"Weather permitting, we're hoping to have traffic back on the southbound side just prior to Thanksgiving," said Capehart.

The southbound lanes are the key, because the northbound lanes are already finished. Drivers have their doubts on the projected timetable.

"I just don't believe it," said one driver. "They've been doing this mess for so long now. Whenever they stop something, they start something else."

The DOT said the bill for smoothing the ride is part of the original $58 million contract. They could not supply WRAL with the exact cost of the diamond pavement cutting.