How do the speed cameras work?

Mobile Speed Vans: The Avondale Police Department deploys a mobile speed van throughout the City. This van is staffed by an American Traffic Solutions employee, who is visually observing each violation. The vans are setup with a sophisticated RADAR unit that monitors vehicle speeds as traffic approaches and passes the van. If a vehicle is exceeding the enforcement speed (11 mph over the posted limit) the RADAR unit signals the cameras to take a picture of the violating vehicle as it approaches the enforcement van and a second image as it goes past the van. These images document the driver, vehicle and license plate of the violating vehicle that the ATS employee observed.