Quantitative Evaluation On Urban Collector Road Functional Reliability And Lane Form Optimization Design

In the urban road network,roads in different grades play different functions,which constitute the framework system of a city together.In “Code for Design of Urban Road Engineering”(CJJ37-2012),according to the functional responsibilities in the road network,urban road is divided into four grades: expressway,arterial road,collector road and branch way.The 3.1.1 on the collector road function description:collector road should focus on the function of collecting and distributing traffic,both service function.The traffic operation of urban roads does not match with the functional orientation in urban road network system planning and design,which has been an important factor leading to traffic congestion in many cities at this stage.This paper based on the project of National Natural Science Foundation of China,starting from the function of collector road,studies on the urban collector roads.The primary road network system consisted of collector road,expressway and arterial road.Collector road is the aisle to connect the city main road and branch way,but also the intermediate link to achieve connection between urban road service functions and traffic functions.According to function description of collector road in“Code for Design of Urban Road Engineering”(CJJ37-2012),“traffic flow of branch road is collected into arterial road through the collector road”and “traffic flow from arterial road is dispersed into branch road through the collector road”are taken as study objects.Definition of collecting and distributing functional reliability of urban collector roads is put forward.As the quantitative evaluation index of collector road function realization,its corresponding mathematical model is established.Then,two collector roads in Zhengzhou city are taken as numerical examples.Based on traffic delay data,signal timing and traffic volume,irrelevance of “ two different intersections ' left-turn delays ” is testified.Furthermore,reliability values of“collecting function” and “distributing function” are respectively calculated.Through comparing with the actual traffic operating status,feasibility and applicability of the proposed method are proved.According to the functional orientation and problems in running situation of the collector road,the optimal design scheme of lane division is put forward.Thinking of the factors influencing the collector road function on the basis of function evaluation,lane division is taken as our optimization design content;the "three-lane" form is taken into the improvement strategy of collector road function;with the help of Synchro and VISSIM simulation tool,the delay in different directions is taken as the index,and then the contrast analysis of possible influence presented by various lane division under three kinds of different traffic conditions is be given.