Traffic

One year in, Cary's left-turn intersection experiment called a success

Posted January 27, 2021 5:29 p.m. EST
Updated January 27, 2021 7:18 p.m. EST

— Nearly a year ago, the North Carolina Department of Transportation came up with a plan to ease traffic flow at intersections where a lot of drivers make a left turn. They identified two locations and put a new traffic pattern in at one – Tryon Road at Cary Parkway.

Called the "dynamic left turn," the intersection has two left turn lanes. On Tryon Road headed east, during rush hour, both are open. But one lane is shut down when traffic flow is lighter.

The dynamic left turn forces drivers in to one lane. Engineers can then allow for a blinking yellow light which allows drivers to turn left when safe. Oncoming through traffic doesn't have to stop for a red light as often.

“We think it's working well,” said Joseph Hummer, state traffic management engineer.

Still, even nearly a year in to the new left turn, a sampling of drivers admit confusion.

“It confuses me every time I come this way,” said one driver who did not want to give her name.

Each driver may save only a few seconds, but Hummer estimates a total of 18 hours of engine idle time is saved each day.

“We believe if we do this at a number of intersections and interchanges throughout everybody's drive, that adds up to something real at the end of the trip,” Hummer said.

Right now about 85 percent of drivers who turn left use the dynamic left turn lanes correctly.

“We wish the rate was 100 percent,” Hummer said. “Honestly, we don't get 100 percent with any traffic control device, no matter what we put out there.”

That's why Hummer thinks self-driving cars may have an advantage.

“Our problem is how do we communicate to the driver and tell him or her not to be in that rightmost lane. But when there's a computer doing the driving, the communication is much easier,” he said.

The state has no firm plans yet to expand the experiment to other intersections. However, it has been enough of a success that North Carolina will be presenting a paper on the dynamic Left turn to other states on Thursday.

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