Study on Freeway Congestion Propagation in Foggy Environment Based on CA-SIR Model

The visibility in a foggy environment has significant impact on driver behavior and traffic flow status, especially for whole closed highways with long distances between entrances exits. Foggy days are very likely to cause congestion even secondary accidents, which seriously affect the reliability of freeway operation. In order explore influence fog jams, firstly, this paper was based analysis days. Light fog, medium heavy were classified as one scenario, while dense weather set separately an extreme scenario without considering lane change. Furthermore, it used SIR model infectious disease reference, combined cellular automata (CA) model, car-following lane-changing rules different scenarios safe driving distance speed two scenarios. Finally, key parameters CA-SIR calibrated, such propagation, recovery probability, vehicle braking, probability. simulation showed that decrease speed, phenomenon propagation more prominent, but causes queuing different. A low limit main reason jams light condition. condition, frequency related random braking probability visibility. conditions, area gradually moved upstream passage time. Moreover, congested time; however, vehicles accompany each other, traveled downstream synchronously time did not dissipate easily. Therefore, environment, best should be better established under visibilities, highway strictly controlled if necessary, worse situations than high-density visibility, avoid spread congestion, intermittent release lanes is suggested implemented.