Types of traffic light sensors
The three most common types of sensors are inductive loop, camera, and radar. Each has its advantages and disadvantages, and where you find them depends on the type of sidewalk, the regional climate, and the financial resources of the city or state.
Induction loop sensors
Inductive loop sensors are embedded in or beneath the pavement and use changes in magnetic fields to detect vehicles. Their coiled wire is charged with an electrical voltage that changes when a large piece of metal comes within range.
While these are very reliable, they need to be replaced every time the road is repaved, which has led to the emergence of other types of detection such as cameras and radar, says a Denver Metro traffic engineer with the Colorado Department of Transportation (CDOT).
Detection of video cameras
Video camera detectors point to oncoming traffic, and some offer a 360-degree view. The latest generation can also detect bicycles.
“These are very useful for tracking vehicle movement patterns across multiple lanes,” says Sabastian. “Studies show that video recognition systems can reduce traffic delays by up to 20%.”
However, they do have some shortcomings, says CDOT. “The main concern is that the lens can become dirty or glare, just like our eyes,” they say. “Sunrise and sunset can also blind a camera for several minutes, resulting in erratic behavior for a short time.”
Radar detection
Radar detection works similarly to cameras, but uses radio waves to detect approaching vehicles. This can give it an advantage over video cameras because it doesn’t operate within the visible light spectrum, CDOT says.
Radar detection is also effective at detecting faster-moving vehicles, says Sabastian, so they are often found at high-speed intersections and highway on-ramps.
Types of traffic light sensors
The three most common types of sensors are inductive loop, camera, and radar. Each has its advantages and disadvantages, and where you find them depends on the type of sidewalk, the regional climate, and the financial resources of the city or state.
Induction loop sensors
Inductive loop sensors are embedded in or beneath the pavement and use changes in magnetic fields to detect vehicles. Their coiled wire is charged with an electrical voltage that changes when a large piece of metal comes within range.
While these are very reliable, they need to be replaced every time the road is repaved, which has led to the emergence of other types of detection such as cameras and radar, says a Denver Metro traffic engineer with the Colorado Department of Transportation (CDOT).
Detection of video cameras
Video camera detectors point to oncoming traffic, and some offer a 360-degree view. The latest generation can also detect bicycles.
“These are very useful for tracking vehicle movement patterns across multiple lanes,” says Sabastian. “Studies show that video recognition systems can reduce traffic delays by up to 20%.”
However, they do have some shortcomings, says CDOT. “The main concern is that the lens can become dirty or glare, just like our eyes,” they say. “Sunrise and sunset can also blind a camera for several minutes, resulting in erratic behavior for a short time.”
Radar detection
Radar detection works similarly to cameras, but uses radio waves to detect approaching vehicles. This can give it an advantage over video cameras because it doesn’t operate within the visible light spectrum, CDOT says.
Radar detection is also effective at detecting faster-moving vehicles, says Sabastian, so they are often found at high-speed intersections and highway on-ramps.
