ResearchonRoadConstru_省略_ImpactuponTraff.doc

5HVHDUFK RQ 5RDG &RQVWUXFWLRQ V ,PSDFW XSRQ 7UDIILF )ORZHang ShenSchool of TransportationWuhan University of TechnologyWuhan, CAbstract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eywords-road construction; traffic distribution; roadimpedance function; shortest path with capacity limitationI. INTRODUCTIONThe distribution of road traffic flow is the result oftravelers choices of their travel routes. Road constructionwill affect their choices and influence traffic distribution inthe road network. The study of how the constructioninfluences traffic distribution can not only provide a standardto evaluate the projects feasibility, but also help trafficmanagement and planning department to adoptcountermeasures to rationally conduct traffic management tominimize the negative impact of the construction project1,2. So its of important practical significance to study thisissue.At present, there is little study about the influence of roadconstruction on traffic flow, the existing papers are studyingHuiyuan JiangSchool of TransportationWuhan University of TechnologyWuhan, CII. THE IDEA TO ANALYZE THE INFLUENCE OF URBANROAD CONSTRUCTION ON TRAFFIC FLOWUrban road construction will change the characteristics ofthe constructed road, the main idea to analyze how roadconstruction influences the distribution of traffic flow is tofind out how the changes of road characteristics impacts thedistribution of the traffic flow, so this paper uses roadimpedance function to reflect how road construction affectsroad characteristics, and assumes that traveling routes arealways the shortest paths. On the basis of this presume, aconnection is established between road impedance functionand the final state of traffic flow distribution in road networkby applying shortest path with capacity limitation method,therefore, if there is a certain impedance function, then wecan find a corresponding traffic flow distribution state. Butroad construction can change the road impedance function,and creates a new function, so a new correspondingdistribution state is created.Using MATLAB to write a program for the shortest pathwith capacity limitation method, and calculate the trafficflow distribution state before the construction, calculate thedistribution state during the construction and after theconstruction respectively. After comparing the three differentstates, the influence of road construction on traffic flowdistribution can be described qualitatively and quantitatively.And can provide a basis for taking correspondingmanagement measures during the construction.the model and organization of expressway reconstruction andextension engineering 3,4. And those concerning this issueare mostly qualitative papers, and some papers only concernIII.THE MECHANISM HOW ROAD CONSTRUCTIONIMPACTS TRAFFIC FLOWthe influence of motor cars and ignore the influence of non-motor cars. In order to overcome these defects, this papercombines the road construction issue with traffic assignmenttheory organically, after concerning the influence on trafficdistribution of both motor cars and non-motor cars, thispaper applies shortest path with capacity limitation methodto distribute traffic volume, and applies MATLAB softwareto program and calculate data, and analyzes the influence ofroad construction on traffic flow distribution quantitatively._978-1-4244-9598-6/11/$26.00 2011 IEEE429Urban road construction will have a negative impact onthe travel condition of the surrounding area, the constructionwill lead to the close of the road, so the original trafficvolume of the road have to be transferred to the other roads5,6. After the construction, the improvement of thetechnical standard of the road will attract more travelers tochoose it instead of the others.A. Road Impedance FunctionRoad impedance function represents the relationshipbetween the actual travel time and traffic load, manydomestic scholars conduct a lot of research about roadcharacteristics and find out the relationship of some of thecharacteristics can be described as the following expressiot t01 k1 (V1 / C1 ) k2 (V2 / C2 )(1)In the equation: t means the actual travel time of theroad segment (minutes);(8)tt01 (k1C1 C4k212)V1 t0 means the travel time of the roadwhen traffic volume is zero respectively (minutes); calculated by historical data of the former period, and willV1V2 means the number of motor carsnot change too much in the short term, so the right side of theand non-motor cars (volume/hour) respectively;C1 C2 means the practical capacity ofmotor cars and non-motor cars;k1 k2 are parameters whose value can becalculated by regression;In a single period, the practical capacity of motor carsand non-motor cars on a single road C1 C2 can bedeemed as constant, so equation (1) can be written as:t t01 k3V1 k4V2 (2)impedance function only contains one variable V1 , andbecause the ratio of motor car to non-motor car is a constanta , so the non-motor cars distribution state can be calculatedif the distribution state of motor car is known.B. Impedance Functions Impact on Traffic FlowImpedance function reveals the practical capacity of theroad when there is a certain number of cars running on theroad, during the process of the study of traffic distribution,the assumption that travelers choose the shortest path thatconsumes minimum time as traveling route, from equation(1) ,it can be seen that the increase of traffic volume on theshortest path from node i to node j ,the shortest path will(3)k3k1 / C1not remain the shortest one, so travelers from node i to nodej will choose a new shortest route. So the influence ofimpedance function on traffic distribution is a dynamic(4)k4k2 / C2process, and for a certain impedance function, acorresponding traffic flow distribution state can be calculatedby applying shortest path with capacity limitation method.In the equation, k3k4 are parameters and othersIV.SHORTEST PATH WITH CAPACITY LIMITATIONdefinitions remain unchanged. Assuming that the portion ofmotorcars and non-motor cars on each road segment are thesame, on every road segment, the ratio of motor cars to non-motor car is almost a constant, that is to say:METHODA. Introduction of the MethodShortest path with capacity limitation method is a trafficV1aV2assignment method that takes the dynamic relationship ofimpedance function and shortest path into consideration,(5)(6)a12which believes that all the traffic volume will choose shortestpath as traveling path, meanwhile, when choosing theshortest path, it has to consider the influence of the volumeof motor cars and non-motor cars running on the roads 7. Itconsiders that the shortest path from node i to node j ischanging with the change of traffic volumes distribution onthe road network, and the relationship of traffic volume of aBy using equation (6) and data of the former time, thevalue of a can be calculated, then put equation (5) intoequation (2):single road segment and its actual traveling time can be seenfrom equation (8).When applying shortest path with capacity limitation(7)ktaPut equation (3) and (4) and (6) into equation (7):430method to distribute traffic volume, firstly all the startnodes, end nodes and corresponding traffic volume should bewritten into an OD table, then the table be divided intoM parts, for a single part, the shortest path method isapplied to find out the shortest paths of all pairs of start andend nodes. After the shortest paths are found out, the trafficvolume are distributed to all the segment roads of theshortest path, when all pairs of the start an n:d end nodes are?V?VIn equation (8), k1, k2 , a, t0 , C1, C2 ,V1 ,V2 can all be?V?Vt0 3 4 )V1 1 (kTABLE I.TRAVEL VOLUME OD TABLEoperatedV.NUMERICAL EXAMPLESby thementionedmethod,anotherpart of theOD tableis operatedby thesamemethoduntil alltheM partsaredistributed.The following figure is a regional road network, in thisexample, all the road impedance function are calculated froma detailed analysis of former traffic data of the road network.And are marked in Fig.1, the construction of the roadbetween node 6 and node 7 will lead to the close of road, soduring the construction of the road, no vehicles are allowedto run on the road segment. And after the construction, theimpedance function between node 6 and node 7 becomest67 1.6 0.001v . And its known that during the timeperiod from 15:00 to16:00, all the traffic volume from eachstart point to end point is listed in travel OD table (table1).B. MAT2+0.002v2+0.002v1.6+0.002vLAB1234SimulationstepsThe shortest path with capacity limitation to distribute52+0.002v2+0.002v61.5+0.002v1.6+0.002v71.7+0.002v2+0.002v82+0.002vtraffic volume can be realized by computer, and the detailedsteps are as follow.2+0.002v1.8+0.002v2+0.002v2+0.002v1) Determine the original traveling time matrix ofconnecting nodes, create an OD table named OD1nun formotor cars, create a matrix V 1nun to calculate aggregated92+0.002v102+0.002v112+0.002v12traveling volume on each road segment, and get the value ofk1, k2 , a, t0 , C1, C2 from traffic flow distribution data of theformer period.Figure 1. Original Road Network Impedance Function.2) Divide OD1nun intoelements in V 1nun equal zero.M parts, let i =1, have all theFirstly, apply MATLAB software to write a programbased on shortest path with capacity limitation to calculatethe traffic distribution state (Fig.2), and the average travel3) Modify the traffic volume of the road network, andtime of all the traffic volume is 10.19 minutes.calculate traveling time matrix Tinun .6803906104) Calculate all the shortest path of all the pairs of start1234i5) Distribute the traffic volumei42032058033044035038052048028030042060400segments of the shortest path.56786) When the distribution process is finished, calculateaggregated motor cars traffic volume V1nun = V1nun +300210320360340440260200200480600V1i nun , let i i 1 .92901039011570127) If i ! M , then export traffic volume of all the road500380500segments, calculate the average travel time of the net,otherwise , return to step 3.431Figure 2. Original Traffic Distribution State.Secondly, the road construction leads to the result thatroad impedance between node 6 and node 7 becomes infinity.OriginDestinationVolume/hour1420011020011250041200493504123009130093200912300121600123300129150and end nodes in the OD1 nun table.V1 nun to all theApply the written program to calculate the new distributionVI.CONCLUSIONstate (Fig.3), and the average travel time of all the trafficvolume is 10.64min.Thirdly, when the construction finishes, the impedancefunction between node 6 and node 7 becomes:t67 1.6 0.001v . Calculate the distribution state again(Fig.4), and the average travel time of all the traffic volumeis 10.00 minutes.Road construction has a negative impact on traffic flowin the surrounding area, this paper uses shortest path withcapacity limitation method, write a program to simulate theinfluence of road construction on traffic distribution, byusing a numerical example, this method is proved to beeffective in analyzing the influence of road construction ontraffic flow distribution.REFERENCES6807207301Ruhai Ye, Jiliang Wu. Traffic Organization in Urban DesignUrban1640262032004Design of the South Huaihai Road and North Huaihai Road in HuaiAn J.Urban Architecture, 2007,(02):46-48(Ch).4202603604204403701803002Zufeng Wu, Yongbing Xu. Traffic Control and Management for RoadConstruction Zones Crossing Urban Groups: a case study in280300NingboJ .Urban Transport of China,2009(03):62-67(Ch).52606720083Yongyi Li. Study on traffic organization and project evaluation ofexpressway works sectionsD. Southeast University,2006(Ch).4202803604001401704805004Miao Wang. study on traffic organization of An Xin highwayreconstruction and extension projectJ, highway,2006,(10):135-137(Ch).93405001058058011570600125Sar