Intelligent Speed Limit System for Safe Expressway Driving in Rainy and Foggy Weather Based on Internet of Things

The feature bends and tunnels of mountainous expressways are often affected by bad weather, specifically rain and fog, which significantly threaten expressway safety and traffic efficiency. In order to solve this problem, a vehicle—road coordination system based on the Internet of Things (IoT) is developed that can share vehicle—road information in real time, expand the environmental perception range of vehicles, and realize vehicle—road collaboration. It helps improve traffic safety and efficiency. Further, a vehicle—road cooperative driving assistance system model is introduced in this study, and it is based on IoT for improving the driving safety of mountainous expressways. Considering the influence of rain and fog on driving safety, the interaction between rainfall, water film, and adhesion coefficient is analyzed. An intelligent vehicle—road coordination assistance system is constructed that takes in information on weather, road parameters, and vehicle status, and takes the stopping sight distance model as well as rollover and sideslip model as boundary constraints. Tests conducted on a real expressway demonstrated that the assistance system model is helpful in bad weather conditions. This system could promote intelligent development of mountainous expressways.