Study On Main Technical Indicators Of Freeway Interchange

The design of the current freeway sticks to the rules rigidly. Considering the actual environmental characteristics inadequate,Lacking of flexibility on linear index selection,This creates,the car safety insufficient and serious damageon the environment as well as the cost increases.Analyzes interchanges technical indicators for each land use,cost,the influence of safety and comfort, demonstrates the rational use of indicators and recommends a set of reasonable freeway of technical indicators,as a necessary flexible reference.Analysis of the builted national highway interchanges indicators,Understood the status quo of the indicators used,pointed out the existing problems,Put forward for solving these problems positioning interchange level properly,the design of speed and safety evaluation.Evaluates part of the ramp which using speed coordination evaluation theory.Concluses the main technical index of the coordination and the relationship between value and speed,on the basis of this,we analysis the main technical indicators and the using status recommended,the minimum plane curve radius of highway interchange ramp,the minimum parameters of easement curve,the maximum longitudinal grade, the length of deceleration lane,the minimum radius of vertical curve and the length of recommended value,providing the reference for each flexible design.In this paper, the conclusion mainly include the following:(1)ramp linear index is the key factor of affecting the land for interchange and cost;The lower limit index of ramp itself is not reasonable use, which will affect the safety and comfort of interchange.(2)radius changes impact on speed coordination of passenger car ramp more than big trucks, in order to guarantee the stability of the passenger car running, we should avoid excessive amounts of circular curve radius, conservative general value relatively in the specification, and increase appropriately.(3)the changes of easement curve parameter on the car to the ramp speed coordination put more effects than the big trucks,the minimum radius of circular vehicle on the ramp put forword more speed coordinations than the influence of the parameters to the easement curve.(4)the longitudinal slope for large truck is very big,the influence of the exit ramp and entrance ramp up/down, increasing the running speed of longitudinal slope and the big truck affected,should be considered to increase exports of ramp,entrance ramp up/down, and the maximum longitudinal grade indexes,in order to prevent the potential safety hazard exists(5)According to the specification of a single design ignored,plus and deceleration lane length values, the length of the ramp at all levels must be taken into account of the influence of the design speed comprehensively,operating speed and traffic flow,and recommends a set of suitable value.