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Indiana engineers create stoplight technology to improve safety at high-speed intersections

The new technology can extend a green light or turn it yellow sooner based on drivers' speed.

LAFAYETTE, Ind — Each year, more than 3,000 people are killed in car crashes at intersections across the country. Thousands more are hurt.

But a team of engineers in central Indiana is working to make those intersections safer.

"If we can do anything to bring down those numbers, that would be huge," said Jijo Mathew, transportation research engineer with the Joint Transportation Research Program in Purdue University's Lyles School of Civil Engineering.

Purdue University researchers along with the Indiana Department of Transportation have developed sensor technology to prevent drivers from running red lights at high-speed traffic signals.

They recently tested in at an intersection in Tippecanoe County.

"It went really well," Mathew said.

Here's how it works:

As drivers approach an intersection, they drive onto what highway engineers call the "dilemma zone" — that spot where you're going too fast to safely stop, but you can't clear the light before it turns red either.

It can be a dangerous decision.

This new technology can sense your speed before you get into that dilemma zone, and either extend the green light so you can safely get through, or turn it yellow sooner to give you enough time to slow down and stop.

Mathew calls it dilemma zone protection.

Their sensor — when installed in a traffic signal — can detect a vehicle up to 1,000 feet away. They say the technology is especially important along busy highways.

"We have a lot of these in Indiana," said Howell Li, principal research analyst, "where the speed limit is 55 miles an hour and there are traffic signals." 

Li added it is critical for heavy trucks.

"Their braking distance is one and a half football fields, so they need to make that decision even earlier," he said.

For now, the technology is patent-pending, and it needs clearance with federal regulators. As for when drivers will see it, the team says it will likely be down the road another few years.

But they're confident they'll get the green light.

"Oh I'm confident," Li said. "Absolutely."

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