Safety evaluation of mountainous expressway based on geometric alignment indexes

By analyzing the relation between traffic accidents and geometric alignment, traffic safety evaluation method of the mountainous expressway section based on geometric alignment index was put forward. Firstly, applying the principle of statistical analysis, the relation models of horizontal and vertical alignment indexes and accident rate were built, so the basis accident rates of sections of different alignments were determined by the model. Then, using the basis accident rates with different sections, the concepts for accident rate coefficient of single alignment and integrated accident rate coefficient of combination alignment were put forward, as well as the calculation formula and reference method of the coefficient were given. Finally, according to the integrated accident rate coefficient and principle of statistical distribution, the traffic safety evaluation method of section based on geometric alignment index was put forward. The case analysis was carried out. The result shows that this method can evaluate the traffic safety of mountainous expressway section from aspect of geometric alignment index.