Study on the Relationship between Water Accumulation and Linear Shape in the Ultra-High Transition Section of Expressway

Due to the existence of zero slope section, the outer lanes of the flat curve ultra-high transition section of the expressway often become waterlogged sections and accident-prone sections on rainy days, and the number of traffic accidents shows an increasing trend with the increase of lanes. Based on the calculation model of pavement water film thickness of HintCAD software, this paper explored the relationship between the water accumulation on the road surface and highway longitudinal slope, ultra-high gradient rate, and pavement width in the combination of ultra-high transition section and straight slope section of the expressway and established the corresponding functional regression model. Then the paper further proposes the traffic safety measures for expressway traffic on rainy days to reduce the possibility of water accumulation on the road surface of the flat curve ultra-high transition section to improve the safety capacity and service level of the expressway.