Research on Dual-infrared Laser Based Speed Meter for Tunnel Traffic

With the rapid development of economy in China, the number of tunnel construction projects is increasing rapidly, and the tunnel safety issues are becoming more and more important, especially some tunnels with large traffic flow. Due to the relatively large traffic flow, unclear vision and narrow space, these tunnels are prone to traffic accidents. According to the statistics of China's traffic police department, the accidents caused by vehicle over-speeding account for a large proportion of many tunnel traffic accidents. Therefore, it is urgent to solve the problem of tunnel over-speeding and ensure tunnel safety. However, the traditional speed measurement method (for example the Doppler-radar based speed meter) is not applicable to the tunnel traffic. In order to make up for this defect, the project aims to develop a dual-infrared laser as a sensor to directly measure the instantaneous speed of vehicles in the tunnel through the time difference triggered by the infrared laser and the fixed distance. In this study, the experimental verification of the dual-infrared laser instrument was carried out in the open road section and in the tunnel. The experimental results show that, in the tunnel, the dual-infrared laser based speed meter can successfully detect the instantaneous speed of vehicles, and the error range meets the metrological verification requirements of China. The research results can help relevant traffic departments to monitor the speed of the tunnel, thus reducing the incidence of traffic accidents in the tunnel, and can also play a powerful deterrent role, making drivers dare not violate the rules at will, so as to facilitate the safe operation and management of the tunnel.