Study On Optimization Design Of Single-lane Ramp Width Of Urban Interchange

City Interchange One-way cycling ramp is a basic type of city interchange ramp,and its cross-sectional design is a key part of the interchange design.The one-way ramp of interchange lane cross section consists of a motorized single lane,an emergency stop belt,a curb belt and a shoulder or fence.Along with the continuous development of the automobile industry,the car performance and other aspects are keep improving,and the available land area of the city is reducing,so through design the ramp cross-section by taking measures which are scientific and reasonable,and not only through this way is conducive to saving urban land area,but also benefit to saving construction project costs.Based on the existing data of domestic and foreign about city interchange and road width design,and combined with specific on-site observation and investigation data,then by means of analyzing the width optimization of one-way bicycle lane under the influence of design service level,design speed and design capacity Value and so on,in order to provide a scientific basis of determining the width of the ramp.Passing through analysis the width of each section of the cross section of the one-way bicycle lane,the paper focuses on the safety width of the traffic lane and the width of the right side of the hard road(which is the width of the emergency stop belt).Combining with the current situation and future development trend of traffic composition on the cross-sectional,so as to meet the design requirements and to ensure the new ramp cross section will be meet the technical feasibility,also to meet the economic requirements,putting forward the ramp cross-section width optimization value.Firstly this paper analyzes the traffic characteristics of the one-way bicycle lane on the city,and from this learning the running mode and speed of the car on the ramp and many other content.Then,by analyzing the width of the unidirectional cycling ramp in the relevant norms at home and abroad,as well as analyzing the five factors which are influence the width of the one-way cycling ramp,namely,the traffic volume,driving efficiency,the design speed,the vehicle type with composition as well as emergency stop,next combined with the current traffic composition on the current situation and the development trend of urban interchange single-lane ramp,and analysis of the various components Of the one-way cycling ramp on urban interchange.Ultimately determine the width of one-way bicycle lane can be optimized.Because the width of the roadway is related to the width of the vehicle itself and the horizontal safety distance,this paper by reference the Porakov model which already has been amended process to determining the safety width of the traffic lane;then combining the optimized emergency stop belt’s width,we can get the optimized the width value of One-way cycling ramp,and what is the next thing is carrying on the economic analysis 、technical analysis and security analysis of the optimized value.Finally,the feasibility of VISSIM simulation software is used to simulate the feasibility of unidirectional single lane ramp width by building simulation model.In order to guarantee the optimal width can be maintained to keep the normal operation of the vehicle and ensure the actual capacity of the ramp to meet the design capacity.