Study on reasonable length of long steep slope on freeway based on actual loading rate

In order to improve the traffic security level of freeway, this paper first analyzed the mechanisms of traffic accidents on long steep slope. Then, traffic conditions under different actual loading rates and slope lengths were simulated by Vissim. According to security evaluation measured by average speed and conflict intensity, reasonable slope length was selected under certain loading rate. Finally, the simulation model was applied in the case of long steep slope reconstructing for Huangmei-Huangshi freeway. Researches indicated that the model conformed to the actual situation.