Safe Spaces: Radar detectors at traffic signals improve safety at intersections

Wednesday, October 4, 2023–10:05 a.m.

-Georgia Department of Transportation-

Should I stay or should I go? That’s often the question drivers ask when they reach the “Decision Zone,” the area approaching an intersection where some will decide to stop and others will go through the signal when it changes to yellow. That decision by a driver can result in crashes if they hit their brakes too hard or speed through the intersection.

The Georgia Department of Transportation (GDOT) in Northwest Georgia recently implemented Dynamic Decision Zone Detection (DDZD) systems at all intersections where the speed limit is 65 MPH. The system measures the speed of approaching vehicles and adjusts the signal timing to shift the decision zone for each individual vehicle; adjusting for the decision zone based on the speed of the approaching vehicle. 

The DDZD systems reduced abrupt stops by 71 percent and red light running by 80 percent since their installation in recent months. The systems are not used for reporting speeding drivers, and they do not issue citations.

“By adjusting the decision zone we can help drivers make the right decisions when approaching an intersection,” said GDOT District Six Engineer Grant Waldrop. “The results so far have been very encouraging.”

The DDZD systems have only been utilized in a handful of jurisdictions across the country, but that could change in the coming years if the statistics continue to show positive results.

“These advanced systems work because they assist drivers in making an important decision that can have serious consequences,” Waldrop said. “I expect we’ll see more of them because they do improve the safety of intersections, especially those in areas with higher speed limits.”

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