Dr. Traffic

Technology helps cut danger of ‘rebel run’ during change to red light

Traffic signals in Charlotte give drivers a few seconds to clear the intersection after the light changes to red. Busy intersections such as this one at Fairview and Sharon roads in the SouthPark area require extra attention and caution.
Traffic signals in Charlotte give drivers a few seconds to clear the intersection after the light changes to red. Busy intersections such as this one at Fairview and Sharon roads in the SouthPark area require extra attention and caution. rlahser@charlotteobserver.com

Look both ways before crossing the street.

That advice is not just for grade-schoolers. Many of Charlotte’s multilane, high-octane intersections are erratic enough to call those words from the wells in your brain.

As soon as your light turns green, instinct should warn you: Watch out for a “rebel run.” Some bad boy (or sassy girl) might buzz through the red light just as drivers on the cross street are hitting the gas.

“There are some intersections you are suicidal to go through when it first turns green,” Linda Allen of Charlotte wrote. “Wish it was a little safer to go when the light turns green. Maybe the change time should be a little longer.”

Urban traffic engineers are generally well-versed in the outcomes of red-light running. It took nearly 7,800 lives between 2004 and 2013, according to the National Highway Traffic Safety Administration.

About half of those killed by red-light running were pedestrians, bicyclists and passengers in other vehicles, according to the Insurance Institute for Highway Safety. Motorists in urban areas are more likely to be injured in these crashes than in any other type of wreck, according to the institute’s research.

As a result, Charlotte and many other cities program delays at traffic signals so that no one will have a green light for a few seconds.

“We call it all-red time, where nobody is moving,” said Charles Abel, transportation systems manager for Charlotte Department of Transportation.

Charlotte’s 755 traffic signals have had this feature for at least 20 years, Abel said. The length of the delay is based on the time it takes a vehicle to go through the intersection at the speed limit, Abel said.

“It varies,” he said. “The distance through the intersections varies.”

The calculations are made carefully because longer all-red times can become counterproductive, Abel said.

“The longer you make that time, the more you encourage people to use it as far as going through it,” he said.

Even for those with good intentions, it’s not always easy to slow down and stop as the light changes – our timing can be off now and then.

To stay out of trouble, it’s best to stop your vehicle if the light turns red before your wheels cross the roadway marking known as a stop bar. It’s a solid line that you reach before coming to a crosswalk.

Passing through the intersection should be OK if your wheels are already beyond the stop bar when the light turns red, Abel said. You also get a pass if your vehicle is already in the intersection for a left turn.

Of course, someone is asking whether running a red light is a violation if no one is around to see it. We’ll leave that one for a judge to answer – after a red-light camera catches the rebel in the act.

Karen Sullivan: 704-358-5532, @Sullivan_kms

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