Abstract:As the rapid development of economy in China,a great number of highways in mountainous areas will confront with more and more rockfall problems. Obviously,risk analysis of encountering rockfalls along these traffic routes is of extreme importance for zoning of rockfall hazards and optimum scheme of mitigation costs. Based on the EGMS methodology,a comprehensive way is developed to estimate frequency of rockfalls occurred in difficult mountainous conditions by combining all the information from site investigation,experiences and theoretical analysis. It is supposed that human activities and potential rockfalls in a rockfall zone are uniformly distributed,and some formulas are obtained from Bernoulli formula to compute probability of encountering rockfalls under three situations,i.e.,immobile vehicles,mobile vehicles and foot passengers. Thus,risk levels of passing different rockfall zones can be successfully achieved from further vulnerability analysis and the annually averaged probability of encountering rockfalls.