FAQ - Video Cameras at Signalized Intersections
What are the cameras for?
The overhead cameras you see at a traffic signal are solely 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.
The cameras are not focused on you the driver, 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.
Why are the cameras attached to the signals so high?
Who is watching me through these cameras?
How long are the videos kept?
Are these cameras tracking my movements?
Why go through the extra expense of installing cameras?
These in-ground loops have both near-term and long-term costs. The labor for a work crew to saw-cut pavement while shutting down that lane of traffic, and the cost of material (wire, conduit, loop processors) are immediate costs. In the long run, additional costs pile up. The saw cutting of the pavement weakens its strength, resulting in shorter service life and more maintenance costs for pavement repair. When in-ground loops fail, the entire loop must be recut into the pavement again, so the labor and traffic disruption costs are renewed. Video cameras give us low cost options to change the detection boxes do to construction or lane shifts, pavement loops do not.
Video detection cameras, like most electronics, have seen their costs steadily drop since the technology was first introduced. Camera processors, like all computers, have increased their capability as prices drop. Installation is done above the surface of the road, and usually away from the flow of traffic. The pavement remains undisturbed and is capable of lasting longer. When cameras or processors fail, they are simply and quickly replaced without a great disturbance in traffic flow.
Comparing the overall costs of the in-ground loops vs. the overhead cameras today gives the cameras the edge. It is an efficient use of taxpayer money for the job they perform.