Road surface meteorological conditions are very important for traffic safety. According to the statistics, the ratio of traffic accidents that occur on icy, wet and dry road surface is about 4.2:1.6:1. A remote road surface meteorological condition sensor based on multi-wavelength light was developed in this paper which could identify the road surface condition including dry, wet, icy and snow, that may be vital for preventing traffic accidents. By using multi-wavelength optical remote sensing technology and near infrared light source, the diffuse reflectance spectrum of road surface can be detected. The four road surface states of dry, wet, ice and snow can be measured with non-contact method, and the thickness of pavement water film can also be measured. Such road sensors were used on G50 highway in Chongqing, China. Experiment results show that the system could meet the requirements well.
In order to reasonably determine the safe speed limit of expressway under several meteorological conditions such as stagnant water, icing, snow, fog , and provide the driver with the maximum acceptable safe speed, this paper proposes a Freeway variable speed limit system based on traffic meteorological environment monitoring. This paper establishes a speed limit model based on visibility, illumination and road surface state. The STM32f103 is proposed as a controller to collect meteorological information in real time using road surface condition monitoring equipment, visibility meter and illumination meter. And use LED information board to prompt the maximum safe speed in real time. This paper is based on QT5 development of the host computer client. QT has the advantages of high modularity and good reusability, and can be extended to other functions as needed.