“Adaptive” Signals to Improve Red-Light Gridlock

The city of San Diego is testing a new light system that can adjust traffic flow depending upon the situation.

Targeting areas where population is becoming denser, city engineers are working on a way to end the red light gridlock with adaptive signals. 

While it may not help areas with consistent traffic, they are working on places with peak flows at different times of the day, which could include drivers coming and going from concerts, theater or work.

Essentially, the lights will talk to each other, according to Bill Harris with the city’s Transportation and Storm Water Department.

“When the peak is coming out of the parking lot, that first light is going to go, ‘OK, here they come,’ and it’s going to let a big bunch of traffic through,” explained Harris. “Each light ahead of it is going to go green just in time to catch that wave, then cross traffic comes through, then the same thing.”

Four intersections in the city already use adaptive signals: those leading to and from the Qualcomm headquarters in Sorrento Valley. The company paid for the system to ease its employees’ commutes.

“It seems to be working very well and we're going to expand it to five other locations up there,” said Harris. “But it looks like they will work in areas all over San Diego.

When the time comes to install the equipment, Harris estimates it will cost the city about $50,000 per signal. Even with the high price tag, he said it beats the cost of adding a lane.

The city has not released a timeline for when the additional lights will be added at the five Sorrento Valley intersections, but when they are done and tested, they plan to add adaptive signals to the west end of Miramar.

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