Research On The Theroy And Application Of Vehicle-bicycle Conflict At Intersections

Mixed traffic refers to the situations in which motorized, non-motorized vehiclesand pedestrians share the same carriageway in time and space. There are threesub-categories: the mixed traffic flow with various vehicle types; the mixedmotorized and non-motorized vehicle traffic flow; and the traffic of pedestriansalong with motorized, non-motorized vehicles. Usually, mixed traffic we refer to isthe latter two, among which the mixed motorized and non-motorized vehicle trafficflow, especially when motorized vehicles and bicycles share the same carriageway,is the main characteristic of urban traffic in China, which brings great trouble totraffic management and results in a key reason to traffic chaos. For example, theconflict between vehicles and bicycles causes more inefficiency in traffic operationand more traffic accident in road. At present, the research domestic and abroad inthe field is too limited to meet the demand of modern traffic management on mixedtraffic. Therefore, This paper focuses on the mechanism of automobile-bicycleconflict and the basic parameters of bicycle flows in such mixed traffic situationsbased on the Key Project of National Natural Science Foundation "Research on theprincipal theoretical model and simulation technique of dynamic trafficmanagement and control in urban network", the Project of National NaturalScience Foundation "Research on Conflict Mechanism and Essential Parameters inMixed Traffic", the joint research project for Hisensoft Network Science Co. Ltd"Research on the theory, algorithm and simulation of self-adapted controltechnique theory and simulation technical in mixed traffic situation".The content of this paper main include four parts. First, bicycle characteristicparameters are analyzed, mainly including the principles of bicycle flow queuing,dispersing and passing at intersection. Second, apply Traffic conflict technique toevaluate traffic safety of mixed traffic intersection compared with tradition accidentmeasure method. Third, Study is made on the automobile-bicycle conflict to theefficiency of traffic operation at intersections. The quantitative relation model is tobe put forward for understanding the state and the conflict in traffic flow. The lostcapacity caused by the conflicts is to be analyzed. Fourth, the application ofprinciples of automobile-bicycle conflict is made based on the research about theconflict mechanism, including the critical value for vehicle-bicycle segregation, theequivalent conversion factor of bicycles in all directions, and the green end time inadvance at exclusive bicycle phase of signal intersections under the environment ofmixed traffic flow. Details of every part are shown as follows. It is common to use known data to forecast some uncertain factors in constructand re-construct traffic facilities or deciding traffic management project. Forsolving that, mathematic model of bicycle characteristic could be helpful. Manyparameters of bicycle traffic flow which are stochastic variable can be forecastedby statistical model. This paper studied the bicyclists'traffic behaviors in the process of queuing anddispersing at signalized intersections when it is with various quantities andproportion of traffic flows. It serves as foundation for the successive researchsubjects. The content including characteristic of bicycle arriving and travel speeddistributions in intersection approach in various environment, queue density, travelspeed, flow volume and saturation rate of dispersing bicycle flow based on trafficsurvey. Then, bicycle flow model is established based on survey data, which is veryimportant to estimate capacity and delay of mixed traffic intersection. Intersection is neck of urban traffic where exists much conflict for different ofautomobile, pedestrian and bicycle weaving in that, so it have a relatively highpercentage of traffic accident. In all conflict, automobile-bicycle conflict isprominent, which is main factor for arising traffic operation chaos and safetydecline. So studying traffic conflict can help to decrease traffic accident rate. Traffic conflict technique is a new non-statistic method to evaluate traffic safetyquickly, which also can increase traffic safety measure reliability. This paper applyTraffic conflict technique to evaluate traffic safety of mixed traffic intersectioncompared with tradition accident measure method, analysis features of differenttypes of mixed traffic conflict in urban intersection, defined automobile-bicycleconflict based on traffic conflict definition from critical gap acceptance aspect,develop a probability model to estimate automobile-bicycle conflict numbers fromroadside observations of bicyclists and drivers behavior. Furthermore, this paperalso suggested some measures to decline automobile-bicycle collision inintersection from traffic channelization aspect. In intersections, drivers or the bicyclists do not make way to each other to causecongestion. Both result in lower traffic operation efficiency and road safety. Thispaper attempts to find the intrinsic principles of mixed traffic flow in order toincrease operation efficiency of mixed traffic, thus to understand and exploitfeasible measures for traffic management, apply traffic channelization and signalcontrol technique to solve dispersing paradise of automobile and bicycle anddecline automobile-bicycle conflict at mixed traffic intersection. From mentioned above, This paper presented method of estimating bicycleroad capacity and measures of level of service of bicycle, Study is made on theprinciples vehicle-bicycle conflict at intersections, including the conflict betweenthrough vehicles and left-turn bicycles, the conflict between left-turn or right-turnvehicles and through bicycles. The quantitative relation model is to be put forwardfor understanding the state and the conflict in traffic flow. The capacity and delayof intersection in mixed traffic state caused by the conflicts is to be analyzed. Somemeasure to decrease automobile-bicycle conflict numbers also forwarded fromsignal timing aspect. In intersections without special traffic management, drivers or the bicyclistsusually do not make way to each other to cause congestion with too long red times,which result in lower traffic capacity and road safety. The direct reasons that arousethe problems can be attributed to absent theory aiming to mixed traffic features tosegregate bicycle flow from vehicle flow scientifically, that is, to make full use thelimited spatio-temporal resources to realize vehicle-bicycle segregation throughchannelization design and signal timing in intersections. To solve that, the bicycleequivalent conversion factor is necessary to compare road utility. This paperforwarded a new method to estimate the bicycle equivalent conversion factor andcalibrated it based on survey data.