Q: Hey, all of a sudden grooves appeared across the double-yellow line on Route 145, south of Laurys Station in North Whitehall Township. They remind me of rumble strips (remember those?). Is the idea to keep sleepy drivers on their own side? Are they going to show up all over? Won't they cause the pavement to deteriorate sooner?
Lucas Stiles, North Catasauqua
A: Your assumption is correct, Lucas, center-line rumble strips are meant to alert sleepy drivers or those simply not focusing as they should be, for whatever reason jolting them back to attention through the humming noise and the tactile sensation of feeling the tires bump slightly into the grooves in the road surface.
Patterned after the more familiar rumble strips carved into the shoulders of interstates and other limited-access highways, the center-line strips are intended to reduce head-on and sideswipe crashes.
''Center-line rumble strips,'' state Department of Transportation spokesman Ron Young replied when asked about the grooves. ''They're fairly new.''
PennDOT spokesman Steve Chizmar from Harrisburg put a slightly finer line on the description, pronouncing them ''milled-in center-line rumble strips,'' the kind cut into a finished road surface with a milling machine.
Chizmar said PennDOT began carving the center-line grooves into roads about five years ago.
''In theory, it works the same way as the shoulder rumble strips,'' alerting errant drivers that they're drifting, he said.
PennDOT's District 5, with headquarters in Allentown, started using the strips two or three years ago, district traffic engineer Dennis Toomey said.
Engineers evaluate statistics for head-on and sideswipe crash rates on various roads, choosing those with the highest rates, Toomey said.
''We look for a pattern of head-on and sideswipe-type crashes, and if we have a history of that type of crash, then we have a candidate for the center-line rumble strips,'' he said.
Motorists will see them on specified roads in all six counties in District 5, Toomey said, including on parts of Schantz Road, Route 100 and Route 29 in Lehigh County, in addition to Route 145.
In Northampton County, the strips can be found on sections of Route 611 south of Easton and on parts of Route 248, Toomey said. Rural Berks, with its abundance of winding back roads, has a lot of them, including on sections of Routes 183, 73, 737, 419 and 501, he said.
Engineers try to keep the strips away from homes to make sure the noise they generate affects only the people for which it's intended.
In the Lehigh Valley area, PennDOT pays about $650 an hour to have the center-line strips milled in, Toomey said. The milling machines, which use spinning, toothed, steel drums to cut the surface, clip along at all of about 1.5 miles per hour. But adding setup time, maintenance, material removal and other delay factors, crews can manage only about four miles per day, he said.
And while the practice theoretically might shorten the life of the road, the effect would be extremely minimal, if it exists at all, officials said. The strips are only about a half-inch deep, and unlike surface cracks, don't allow water to flow down to the road bed where the freeze-thaw cycle can undermine the asphalt, Chizmar said.
A University of Maine study in 2002 concluded that shoulder rumble-strips can reduce run-off-the-road accidents by 20 percent to 50 percent, and recommended installing them throughout the interstate system.
The Insurance Institute for Highway Safety is evaluating the effectiveness of the newer center-line strips, though the Warrior could not reach the person in charge of the study to see if conclusions can be drawn yet.
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