Research on Crossroad Access Design Technology in the Functional Area of Urban Interchanges in China

To heighten the traffic safety level of urban interchanges' functional areas, the crossroad access design technology was studied. According to traffic flow features at interchange ramp terminals in China, with the use of the Hick-Hyman Law and Fitts Law to study the distribution of driver perception-reaction and movement time, interchange functional area range's calculation methods were presented. Then, based on the Cowan M3 headway distribution model and gap acceptance theory, the arriving distribution function of crossroad traffic and turning trajectory of vehicles in the driveway were proposed to provide mathematic models for crossroad access design factors, including driveway throat length, throat width, curb radius and clear vision area. Finally, design models were applied to the Xin Zhuang Interchange. With the model of the relationship between traffic stream parameters and crash rate, the paper evaluated safety impacts of crossroad access design using flow and speed values from Vissim. The result indicates that the methods and models are effective for traffic safety.