What do these cameras do?
The overhead cameras you see at a traffic signals are for detecting the presence of vehicles in order to provide the best distribution of green time based on traffic demand. They are cost-effective replacements for in-ground induction loops that are cut into the pavement.
Are these cameras used for law enforcement?
No! These particular cameras are in no way tied to any law enforcement system. They are solely for detecting the presence of vehicles within their view. They are not capable of producing an image detailed enough to read license plates or facial features. However, the city of Arnold, the first city in Missouri, has enacted a local ordinance to allow for red light running camera law enforcement. An entirely separate camera system would be installed for this purpose, as the enforcement cameras are much more detailed in their resolution. These intersections have yet to be determined on MoDOT's system, however, when they are determined and installed, they will be prominently signed to differentiate from the two different camera systems.
Do the cameras issue red light camera tickets?
No! The cameras are not focused on drivers, but instead on your vehicle as it moves towards the intersection. As your vehicle enters defined areas or "zones" within the camera's field of view, the camera's processor detects a change in the "zone". An output is sent to the traffic signal's controller (the computerized "brain" housed in a nearby metallic cabinet controlling the intersection's timing) that says a vehicle is requesting green time for its direction.
Do these cameras capture video?
No! There is no constant surveillance or archiving of these images. The camera view is a fixed focus, fixed location image (there is no zooming or moving the cameras once they are installed). The image is analyzed by the camera processor ONLY for the simple presence of vehicles within defined areas or "zones". The resolution of the image by these cameras is NOT good enough to read license plates or distinguish any facial features, as shown in a typical snapshot here: