新型非常规U型转弯交叉口的运行效率研究

Operational efficiency of new unconventional U-turn intersection

左转车辆对交叉口运行效率影响很大,通过设置U型转弯能够很好的解决主交叉口的交通冲突.针对常规的U型转弯交叉口对中央分隔带宽度的特殊要求,设计一种新型非常规U型转弯交叉口(new unconventional U-turn intersections,NUUT),通过将常规的U型掉头改造为分车道分车型的U型转弯交叉口,来解决道路空间利用以及大小车转弯之间的冲突问题.通过Vissim仿真,对比NUUT、直接左转(direct left turn,DLT)、无专用车道U型转弯(U-turn,UT)以及有1条专用车道U型转弯(one lane U-turn,OLUT)4种交叉口设计中的车辆运行效率.结果表明,在相同的适用交通量条件下,NUUT路网的平均延误率比DLT交叉口降低5.64%~85.73%,停车次数降低6.17%~94.22%,排队长度减少了6.44%~95.38%.在相同的适用交通量和大型车比例变化条件下,相比UT和OLUT,NUUT的设置使路网平均延误分别降低了1.45%~98.00%和0.30%~97.97%.当道路上的大型车比例增加时,NUUT能够有效改善路网的运行效率.与U型交叉口对比,NUUT所适用的最大交通量均呈线性分布,随着主干路交通量的增加,次干路交通量逐渐降低.NUUT设计能够有效提高不同交通量、不同大型车比例情况下的路网运行效率.NUUT在实际交叉口应用中的效果明显,有效降低了交叉口延误.

Left-turning vehicles have a significant impact on the traffic operation efficiency at intersections.However,the traffic conflicts at main intersections can be well solved by setting U-turn intersections.For the traditional U-bend intersections which have special requirements for the width of the central separation belt,a new type of unconventional U-turn intersections(NUUT)is proposed to improve the utilization of road space and to solve the conflict between large and small vehicles in the case of turning.The vehicle operating efficiency of the NUUT is analyzed by VISSIM simulation.NUUT is compared with direct left turn(DLT)lane,no lane U-turn(UT),and one lane U-turn(OLUT).The evaluation results show that the setting of NUUT reduces the average delay-rate of the network by 5.64%~85.73%,the number of stops is decreased by 6.17%~94.22%,and the queue length is cut 6.44%~95.38%,compared with the DLT in the same applicable traffic volume.And it decreases the average delay rate of the network by 1.45%~98.00%and 0.30%~97.97%,compared with UT and OLUT under the same applicable traffic volume and the same large vehicle proportion change.In conclusion,the NUUT can effectively improve the operational efficiency of road network when the proportion of large road vehicles increases.The maximum traffic volume applicable for the comparison with U-shaped intersection is in linear distribution.With the increase of the traffic volume in the main road,the secondary road gradually decreases.The design of NUUT can effectively improve the operational efficiency of road network under different traffic volumes and different large vehicle ratios.