Analyzing the forming principle of design indexes of longitudinal slope,studying the performance,operation security,road capacity and gasoline consumption of automobiles in long and steep longitudinal slopes and realizing the latent security problems existed in design sufficiently can help designers avoid long and steep longitudinal slopes when designing the expressway in mountainous areas.

With the background of the long-steep-slope section of an asphalt concrete expressway in Guangdong Province,the rutting resistance of the asphalt mixture is improved by adopting high modulus asphalt,mineral fiber and additive modified asphalt et al.

It is worse in long and steep slope sections because of special longitudinal slope, which has a strong effect on traffic safety.