Traffic information collection system powered by solar cells

One requirement for a vehicle detector, which is one type of traffic information collection system, is low power consumption and wireless operation. Behind this requirement is the desire to collect traffic information without the need to supply AC power on roads where a commercial power source is unavailable, the importance of aesthetics in urban settings, and conversion to the wireless transmission of detection signals. Further considerations are the call for measures to protect the global environment and the utilization of "clean energy" as an environmental measure. This paper describes a practical traffic information collection system which consists of vehicle detectors powered by small solar cell power sources and a free-space optical transmission device that transmits the detection signals linked by the vehicle detectors.