Drivers, watch your speed


Area motorists traveling to Indianapolis on Interstate 65 will encounter new dynamic speed limit signs the state has begun testing in the hopes of preventing rear-end crashes when traffic slows or stops entering the work zone.

Three signs have been placed on northbound I-65 and three for the southbound lanes in a stretch of the interstate between U.S. 31 at Taylorsville and Whiteland Road in Johnson County, said Harry Maginity, Indiana Department of Transportation spokesman.

Ed Cox, INDOT’s managing engineer of corridor operations, will work with Purdue University researchers today and Tuesday to control the speed limits on the northbound signs from a laptop and modem in his vehicle.

The “dynamic” part of the speed limit signs means that each sign’s electronic display can be changed to adjust speed limits in 5 mph increments between 45 mph and 70 mph, Maginity said.

The signs are being tested as an improvement on the “45 mph speed limit when flashing” signs that INDOT has used in work zones to slow vehicles before travelers encounter slowed or stopped traffic at the entrance to construction zones.

Based on the traffic flow, Cox said, he will experiment with the researchers’ help on how drivers respond to changes made on the speed limit signs.

The Purdue researchers will have radar guns to check speeds of vehicles that pass by the signs to determine what the drivers do when they see the sign and the speed limit, Cox said.

He emphasized that the testing is not an enforcementarea, meaning that drivers will not be ticketed or stopped based on what the radar guns are showing during the test.

Today’s and Tuesday’s testing is the first time this type of dynamic speed limit sign has been tested in Indiana, Will Wingfield, INDOT spokesman said. However, the technology has been tested and used in other states.

The idea behind the signs is to determine if INDOT can use the signs to make entrances into the construction zones safer and to avoid rear-end collisions that occur when drivers aren’t aware there could be slowed or stopped traffic ahead in a work zone.

“A high percentage of work-zone crashes occur when traffic comes to an abrupt stop,” Wingfield said.

INDOT is patching and resurfacing a 10-mile stretch of I-65 between State Road 252 near Edinburgh and State Road 44 at Franklin.

Road construction has resulted in narrower lanes and diverted traffic as one northbound I-65 lane crosses the median and runs beside southbound traffic on the west side of the interstate, Maginity said.

The goal of the testing initially is to allow INDOT to control the electronic signs from Indianapolis, based on mapping and sensor technology already in place that measures traffic flow, so that the signs can be changed to account for fluctuations in traffic and conditions, Wingfield said.

An algorithm is being developed that would allow the signs to automatically adjust to slow traffic down, if necessary, based on the traffic flow data coming from the interstate, Wingfield said.

It will take a few weeks to compile the data collected in the testing today and Tuesday, Cox said.

Then, he and the researchers will return to test the algorithm to see if the switches to change the speed limit are being thrown correctly to slow traffic appropriately as vehicles approach the work zone.

“It’s not a speed trap,” Cox said. “We’re trying to make a better product, and we’re trying to make it safer.”

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