Research On The Length Of Speed-change Lane And Safety Interchange Spacing On Highway

With the rapid development of China’s national economy, highway construction has maderemarkable achievements. With the road network density increases, there are more and moreinterchanges in highway, which makes interchange spacing b difficult to meet requirements ofthe relevant specification. If the spacing between the interchanges is too small, the trafficsafety will be be difficult to guarantee. In order to improve the rationality and safety ofinterchange design, this thesis studies the security of interchange spacing.Firstly, the spacing between adjacent interchange is defined. Through the analysis ofinterchange spacing in road network density, ramp geometric characteristics, traffic flow,traffic signs and driving comfort, the research of interchange spacing is divided into threeparts: acceleration lane, net spacing and deceleration lane.Secondly, by comparing the specification and the calculation method of the speed change laneat home and abroad, the length of the speed change lane is analyzed and calculated separatelywith the research on truck and car which combined with domestic vehicle performance andtraffic conditions. Based on the design speed of highway and ramp, the recommended lengthof speed change lane is put forward.Thirdly, by analyzing the lane change behavior and driving behavior in the segment betweeninterchanges and dividing the interchange spacing into two parts: merge influence area anddiverge influence area, the calculation model of highway interchange safety spacing isestablished with the method of theory of probability and gap acceptance. The recommendedvalue of net interchange spacing is got at the same time.Fourthly, the net spacing of interchange is analyzed systematically using the analyticalmethod of highway weaving sections. The average speed of weaving and non weavingvehicles and level of service within the weaving segment is achieved. With the safety standardof speed difference between weaving and non weaving vehicles, the recommended value ofnet interchange spacing is put forward.Finally using the research results of this thesis, the safety analysis of close interchanges in practical engineering is finished which has a certain practical significance.