Abstract: In order to study the safety of diverting ramp shunting nose end of interconnected interchange under the conditions of different vertical and longitudinal lines. The dynamic simulation analysis of the passenger car is carried out. The vehicle model, the road model and the driver's preview trajectory model are established. By changing the radius of the circular curve and the longitudinal gradient of the diverting nose, simulating the driving conditions under different conditions, the horizontal alignment and longitudinal profile of the diverting nose were studied respectively. The response output of the lateral acceleration of vehicles under different working conditions is obtained, and the influence of different linear parameters on the safety of the diverting nose end is analyzed. The research results show that: at ramp outlet, the safety of long transition curve with small radius circular curve combination is superior to that of short transition curve with large radius circular curve combination. When the design speed of the main line is 120km/h and the longitudinal slope is -5%, the maximum lateral acceleration of the vehicle is 0.58g, and the vehicle sideslip is more dangerous at this time. It is suggested that the longitudinal slope of the diverted nose is less than 4% in the design. In order to ensure the safety of the shunting nose end, when the design speed of the main line is 120km/h, the radius of the circular curved nose round curve is 350m, and the longitudinal slope should be less than -3.5%. And the radius of the circular curve is 300m, and the longitudinal slope should be less than -3%. When the design speed of the main line is 100km/h, the radius of the circular curved nose round curve is 300m, the longitudinal slope should be less than -4%, and the radius of the circular curve is 250m, then the longitudinal slope should be less than -3.5%.

Key words: highway engineering, safety engineering, computer simulation, interchange exit