Optimization of Speed Limit Method for Freeways Considering AVs Under Rainy Weather

Rainy weather significantly affects traffic efficiency and safety on freeways. This study investigates a safe speed limit model for freeways under rainy conditions, considering both human‐driven vehicles (HVs) and automatic vehicles (AVs). The relationship between safe speed limits and rainfall intensity is quantified. The intelligent driver model (IDM) was selected as the basis for this study due to its complexity and applicability. By analyzing the effects of rainfall on model parameters, an improved IDM was proposed, optimizing the expected speed. Simulation results demonstrate that the proposed speed limit method effectively reduces collision rates, with AVs showing superior traffic efficiency, stability, and safety compared to HVs.