Do traffic signals detect the presence of cars waiting at an intersection?
Signalized Intersections are equipped with one of two vehicle detection devices: A loop detector or a video detector. A loop detector creates an electromagnetic field that senses large metallic objects (vehicles). When a vehicle disrupts the field, its respective signal is changed at the next opportunity to allow that direction of traffic to proceed. Note: Motorcycles and some vehicles may not trigger the loop detector. Video detectors, a newer technology, are cameras mounted above a signal that send an image back to a computer which determines if any vehicles are present at that cameras intersection. When a vehicle is detected, its respective signal is changed at the next opportunity to allow that direction of traffic to proceed. Note: Video detectors are not red-light cameras and do not possess a precise resolution necessary to read license plates. Additional Information on the Citys Video Detection System. Sometimes detector devices sense a car that has subsequently made a right tur
