Delay Study For Right-turning Motor Vehicles Considering Conflicts With Crossing Pedestrians

With the rapid development of urbanization in recent years,the number of urban motor vehicles continues to rise,and the mixed-traffic phenomenon is becoming more and more serious at road intersections.Walking still occupies a large proportion in the mixed traffic flow as the highest degree of freedom of short-distance travel under the content of green travel which is advocated by the government.The traffic conflicts between people and vehicles increase the frequency of safety accidents and greatly reduce the use efficiency of roads,especially intersections.Road intersection is the confluence node of traffic flow in all directions,which plays an important role in traffic hub.However,the intersection is also the high-frequency incidence of traffic conflict and traffic accident between motor vehicles and passers-by.Among them,the operation of the right-turning motor vehicle is not controlled by the signal at the road intersection where the special signal phase of the right-turning is not set,and there is often no clear priority traffic signs at intersections,resulting in a particularly serious conflict between the right-turning motor vehicle and passers-by,which will not only cause the delay of the right-turning motor vehicle to increase significantly but also will affect the traffic efficiency of signalized intersections and threaten the safety of pedestrians crossing the street.For the intersection without special signal of right-turning motor vehicles,the rules of road traffic management in our country give priority to passers-by,but from the field investigation,it is found that the right-turning motor vehicles do not strictly abide by the rules which giving way,and the phenomenon of preemptive traffic with pedestrians crossing the street is really serious.When the traffic flow across the street is large,some right-turning motor vehicles will choose to wait for a period of time before they can compete with passers-by.In this paper,we do the following researches on this phenomenon:(1)Analyzing the traffic characteristics of pedestrians and motor vehicles in detail,especially the arrival regularity of crossing pedestrians.The time-distance distributions of right-turning motor vehicles at three signalized intersections in Changsha are fitted with a mathematical model.Based on the on-the-spot investigation and analysis of the conflict process between right-turning motor vehicles and pedestrians crossing the signalized road intersection,the traffic data of road intersections are statistically analyzed from microscopic perspective,and the relationship between probability of individual right-turning motor vehicle which travel forcibly and numbers of pedestrians crossing the streets within the minimum traversible distance is obtained.Then the probability model of right-turning motor vehicles rush at road intersection is established.(2)By analyzing the conflict process between the right-turning motor vehicles and the passers-by without the restriction of the signal phase but with pedestrian signal phase,the situation of the right-turning motor vehicle waiting for a period of time with the pedestrian is considered.In this paper,the traffic delay model of right-turning motor vehicle with right-turning vehicle arrival obeying uniform distribution is improved,and the traffic delay model of right-turning motor vehicle which travel forcibly after waiting for a while is derived,and the traffic delay model of right-turning motor vehicle with Poisson distribution is derived(DRT Model in short).(3)Taking three signal-controlled intersections in Changsha as an example,the VISSIM traffic simulation model is established,and the delay model of right-turning motor vehicle is calculated by combining video observation and manual counting method,and the relative parameter values are calculated and put into the right-turning vehicle delay model.The calculation results are compared with the VISSIM simulation results,and then the rationality of the right-turning vehicle traffic delay model is evaluated.Compare the DRT model calculation delay with the VISSIM simulation processing delay,it is found that there are 1.59 %,2.59 % and 2.67 % errors in the delay of the Shaoshan North-Renmin Middle Road,Xinjian West-Shaoshan Middle Road,and Yingbin-Bayi Road intersections respectively.It indicates that the model has a certain accuracy and has some reference significance to study the traffic delay under the condition of right turn motor vehicle rush.