Driving on city streets lately, motorists have seen the addition of speed cameras to protect them, but how do they work? Nearly every motorist has seen or at least heard about these cameras and has often wondered about the functioning components of the technology. The cameras do not use radar as the guns that the police use to catch speeding motorists do. The cameras use a set of sensors embedded in the road to determine the speed of passing motorists.

The sensors are piezo electronic detectors that are literally sewn into the fabric of the roadway. When a motorist passes over the first set of detectors, a signal is sent to the camera to ready it for a picture. The sensors measure the deflection of the roadway, the movement due to the weight of the car. As the motorist passes over the second set of sensors, the onboard processor in the camera assembly calculates the speed of the passing motorist as a function of the distance traveled and the time taken to travel the distance. Remember from math class the rate, or speed, is distance divided by time or miles per hour or R = D/T.

Simultaneously, the processor checks the legally allowed speed, and if the calculated speed is greater than the speed limit, then the camera snaps a picture of the offending motorist and their license plate. The image is sent to a central processing unit and the license number is searched for its owner. The owner will receive a ticket in the mail within a few days to a week. These fixed location cameras have the ability to detect speed in either direction, but are usually set up for a single direction. The camera also records the time of day, location of the offense, direction of the offending traveling vehicle and the date of the offense.

Multiple lanes of traffic can be monitored by a single camera by placing piezo detectors in all of the lanes to be monitored. The wide angle of the digital camera allows for accurate and precise images of any lane of traffic. These speed cameras can even detect a speeding motorist in a line of heavy and close moving traffic. The angle at which the camera is positioned allows for images to be taken in the most congested traffic areas and times of day such as rush hour and holiday travel days. All of the images and data stored about a vehicle and its owner is kept strictly confidential through the use of a WORM file system.

WORM stands for Write Once Read Many, which means that the information cannot be deleted or changed in any way, shape, or form, thus protecting the offender’s information. The information sent by the camera system is admissible as evidence in court, as is the expert review of the information. All data is sent and received using advanced encryption methods to ensure security during the transfer of data. The speed cameras are calibrated monthly for digital imaging, and every twelve months a speed diagnosis is rendered. This ensures that their accuracy and functionality are at optimum operating levels and that they provide the correct data to the courts and the offending motorist.