Patent attributes
A traffic monitoring system has a controller and sensors placed in or on roads such that vehicles pass over or near the sensors, thereby casting shadows on the sensors as they pass. The sensors may be configured to detect the shadows, and a controller may be configured to determine any of a variety of information about the passing vehicles based on the detected shadows. For example, the controller may count the number of vehicles that pass, determine a speed of each passing vehicle, and determine a length of each passing vehicle. The sensors can be relatively inexpensive so that a relatively large number of sensors can be used to monitor a large area at a relatively low cost. In some embodiments, solar cells are used to power the sensors, and if desired, the solar cells may be used as the sensors for detecting the shadows of the vehicles being monitored.
