Operating speed prediction model and systems of highway based on space compound curvature

Based on the analysis of operation safety data of expressway and the investigation on the spot, the influence of the horizontal, vertical, cross-sectional alignment index on safety were studied. The vehicles track was seemed as the three-dimensional curve. According to the road alignment space geometric properties, the compound curvature of the horizontal and vertical curve combination alignment of expressway was calculated and modified by gradient. Then the relationship between the alignment evaluation index and the operating speed was analyzed. Considering the influence of cross-sectional alignment, the operating speed prediction model of expressway based on compound curvature was established. The prediction model was proved of high reliability through the contrast between field data and model calculated data. A case study was given to explain the application of the research result of this project. At last, the paper compiled the highway operating speed prediction system software (OSPS).