What are the Cameras for at the I-40/Canada Road interchange?

Many residents have noticed the cameras at the I-40/Canada Road interchange. City Engineer Philip Stuckert explains the use of the cameras:

The I-40/Canada Road signals have overhead optical cameras that provide for vehicle detection. They cannot be used for red light violations. The purpose of each camera is to determine the presence of a vehicle in a driving lane. If the camera detects the presence of a vehicle, then information is sent to the signal controller box whereby the controller decides to service that lane with a green light for traffic movement. If no vehicle is detected, then the signal controller does not service that lane of traffic by turning the signals green. This allows the controller to give that “green time” to other legs of the intersection which has vehicles and needs that time to move more traffic through the intersection.

The cameras take the place of induction loops that are installed in the pavement. Induction loops are installed as vehicle detection devices because they are much cheaper than cameras. However in certain conditions such as bridge decks, induction loops cannot be cut into the pavement as they can be in asphalt pavements. Therefore cameras were installed at this signal location.