Research on Optimization Design of Underground Interchange Ramp Radius Based on Driving Simulation

With the appearance of some large-scale underground interchanges, the ratio of rear-end and collision accidents in tunnel ramp circular curve segments have increased. Lack of design code for underground interchanges makes it necessary to study the circular curve radius of the tunnel ramp. First, considering the stopping sight distance and vehicle force analysis, the suggested value of the minimum circular curve radius was put forward. Then, the regressive model between the lateral acceleration and circular curve radius, and standard deviation of lateral offset and circular curve radius, was established respectively by simulation. As a result, the critical values of the curve radius for drivers getting good, general, and poor vehicle lateral stability were obtained. The result of this study provides reference for the design of an underground interchange ramp and increases the traffic safety in tunnel ramps.