At the Alabama Department of Transportation, signal shops play a crucial role in ensuring the smooth operation of state-maintained intersections. Crews are responsible for installing and maintaining traffic signals across Alabama’s roadways. Crews place each signal for a reason, often based on traffic volume, and carefully calibrate its timing to match posted speed limits and intersection spacing. It’s a science and a safety system rolled into one.
What a Traffic Signal Looks Like
A standard traffic signal with three stacked lights stands nearly four feet tall, including its black backplate. Each circular lens is 12 inches wide, roughly the size of a dinner plate and the full assembly can weigh up to 50 pounds. Crews mount signals on mast arms or span wire that can extend 60 feet or more, depending on the road. They strategically time signals to support safe traffic flow and reduce unnecessary stops.
Most signals are equipped with vehicle detection systems, like sensors and cameras. This helps identify when a vehicle is present and triggers the light cycle accordingly. These systems play a crucial role in maintaining traffic flow and ensuring intersections are safe.
“Traffic signals are timed based on the posted speed limit,” said Kevin Purdue, electronic signal shop supervisor at ALDOT’s Central Office. “If drivers go too fast or too slow, they fall out of sync with the signals. Following the speed limit keeps traffic flowing as designed and is also the safest option.”
More than Maintenance
Severe weather, power outages or other emergencies often prompt signal crews to take action. When the power goes out, intersections can become dangerous fast and signal shop teams are ready to respond.
“When the lights go dark, that intersection becomes dangerous fast,” Purdue said. “We’re not just fixing equipment. We’re protecting people. If we don’t do our job right, people will get hurt.”
When severe weather strikes, signal crews don’t hesitate to act, and they don’t act alone. From one end of the state to the other, teams come together to restore traffic signals as quickly and safely as possible.
Smarter Signals, Smoother Travel
Earlier this year, ALDOT’s Southwest Region completed a major traffic signal modernization project through the Regional Traffic Operations Program (RTOP). The upgrade included new controllers and hardware at more than 150 signals, improving reliability and giving engineers greater tools to manage traffic in real time.
The project also enables engineers to monitor and coordinate signals from a joint operations center, supporting faster response and better traffic flow across the region.
What’s new in the Southwest Region:
- Retimed signals are reducing delays and improving traffic flow
- Remote access now allows engineers to adjust signal timing without dispatching a crew
- Engineers actively monitor intersections to identify problems quickly, but they do not record or store any video.
- Crews deploy event-specific timing plans during large-scale events like Mardi Gras or football games
- Ongoing upgrades are improving detection systems and supporting long-term reliability
Technicians may not ask for the spotlight, but their work is at the heart of safer travel. Whether it’s installing a new signal, responding to an outage or ensuring timing is just right, ALDOT’s signal crews are behind the scenes helping Alabama keep moving.
