Study On The Relative Setting Technical Indicator Of Highway Interchange Entrance And Exit

With the gradually completing of national expressway network, the road network density increased, and the requirement of interchange setting also improved. Interchange can make route separate on space, eliminate or reduce the interference between the traffic flows, add the speed and reduce the time delay, and improve the intersection traffic capacity. It plays an important role in vehicle smooth and safe operation. Thus, the standardization design requirements of the interchange become more and more strict, and the research on correlation index of interchange entrance and exit terminal, which is the bottleneck of traffic safety, become more important.First of all, the influence of the mainline horizontal curve on vehicle safe operation was analyzed in this thesis, from the point of view of the mandatory lane changing at entrance terminal, the minimum mainline circular curve radius can be calculated by building a lane changing model, when the alignment was right avertence where the vehicle can keep lateral stability. In addition, to counter the case that the vehicle can accelerate on the upslope when merging into mainline from ramp, dynamic characteristics of the selected vehicle models was analyzed, and speed loss in the process of shifting was considered. The relationship diagram between vehicle’s range and longitudinal gradient can be drawn by using the equation of motion, on the premise of given speed. The mainline longitudinal gradient can be determined by analyzing changes in the diagram. Secondly, by considering the possible combinations of entrance and exit, six setting type was determined which can provide a vehicle safety and efficient operation, and the characteristics were also analyzed. Furthermore, the corresponding distance models which can calculate the space between entrance and exit, were established, by analyzing influence factors. Finally, through the establishment of sight distance calculation model of the mainline export vehicles, the identified sight distance was put forward under different conditions. By analyzing the possible behavior of avoiding the collision between ramp vehicles of downstream and mainline vehicles, the sight distance on merge area was proposed which can meet the vehicle visibility requirements of interchange entrance. The efflux angle meeting vehicle lateral stability can be determined on the basis of the establishment of calculation model.The research provides certain theoretical guidance for the setting of interchange entrance and exit, and also provides methods and ideas for the update of some technical indicators. It can have a certain practical significance in related theoretical research and engineering application in the future.