Minimum Spacing for Continuous Diversion of Ramps in the Form of Left-placement of Right-turn Ramps

To facilitate drivers to identify the road conditions ahead in a timely manner in the case of continuous diversion in the form of left-positioned right-turn ramps at interchanges, the minimum spacing of continuous diversion in the form of left-positioned right-turn ramps was investigated. First, based on the Interchange Rules and considering the actual engineering significance and drivers' behaviour, this paper redefined the range of continuous diversion spacing of right-turn ramps in the form of left- positioning and its diversion forms with different numbers of lanes. Second, the driving demand and characteristics of vehicles under the most unfavourable driving conditions of different ramp continuous diversion forms were analyzed, and the ramp continuous diversion spacing calculation model was established accordingly. Finally, the (unmanned aerial vehede,UAV) aerial photography and Tracker image recognition software were used to analyze the vehicle running speed, headway distribution and lane changing behaviour characteristics of the ramp continuous shunt area under the left-positioned form of the right-turn ramp, to determine the values of the key parameters in the model, and to propose the minimum spacing of the continuous shunt of two-and three-lane ramps under the left-positioned form of the right- turn ramp by calculating the minimum spacing of the right-turn ramp. This study can provide a reference for the design of right-turn ramp left-positioned form, and provide a reference for the improvement of relevant specifications and design rules.