Bridge ‘grates’ on some drivers

Published 2:51 am Friday, June 6, 2008

By Staff
N.C. DOT: Cars
grabbing nubs,
but not sliding
Staff Writer
Some commuters think it wasn’t too slick of the N.C. Department of Transportation to put a new metal grate on the U.S. Highway 17 bridge at Washington.
They say that it makes the span over the Pamlico-Tar River slippery and their cars slide.
What they’re actually experiencing is just the opposite: Small metal nubs built into the road surface are grabbing their vehicles’ tires, a DOT official said Thursday. The metal protrusions give motorists traction and increase safety, DOT officials noted.
The studs are put on bridge grates that otherwise wouldn’t provide drivers enough traction, said Don Idol, assistant state bridge-inspection engineer.
And if they grab too much, the solution is simple: Wait.
Grate replacements are rare in North Carolina because grates are used almost exclusively on movable spans, where minimizing weight is important, Idol said. The U.S. 17 bridge, which swings open to permit maritime traffic to move up and down the Pamlico, needed new gratings because the old ones were going from broken in to simply broken, he said.
The damage wasn’t anything unusual, just the accumulated impact of decades of vehicle wheels rolling over the bridge, officials said. The new gratings should cut the need for maintenance, Lassiter said. And they might last longer than the last set if the U.S. 17 Washington bypass, now under construction, alleviates the traffic load on the bridge, he said.
The new grate also helped reduce noise caused by traffic crossing the bridge, thereby silencing some of its critics, Lassiter said.
Tires make about as much noise on the new grate as they did on the old grate, but, because the grating is new and has few loose pieces, the clangs and rattles of metal striking metal largely are eliminated, he said.
Lassiter said he checked with several residents who had complained about the noise, and they told him the situation had improved. So far, three people have called DOT to complain about the new grates’ traction, he said.
And DOT had to rush to get the new grates installed in time for the Memorial Day holiday weekend and Washington’s Summer Festival, he said.
“We tried to do that to minimize inconvenience to the traveling public and to the boat traffic as well,” Lassiter said. “I think we did a pretty doggone good job.”