空驶出租车是否应使用多乘员车道——考虑合乘与出租车的交通均衡研究

Traffic Equilibrium in the Presence of Carpooling and Taxis:Should Vacant Taxis Use HOV Lanes?

为了探索空驶出租车是否应使用多乘员车道(HOV车道),基于空间结构的出租车市场均衡条件,考虑Logit出行方式划分和路径选择均衡,采用组合变分不等式描述了准许和禁止空驶出租车使用多乘员车道的混合交通系统。将模型和算法应用于一个算例,通过比较静态分析探索了算例中单位合乘车辆平均合乘率、路网中出租车数量与出租车起步价的变化对均衡路网的效果产生的影响,并观测了多乘员车道流量。结果表明:准许空驶出租车使用多乘员车道有可能造成类似Braess悖论的现象,使社会福利降低,而具体是否造成这种现象与路网的参数有关;同时,准许空驶出租车使用多乘员车道取得的效果有限,且基本是由于交通流分配造成,而HOV车道过饱和现象很少出现。除此之外,探索了单位合乘车辆平均合乘率、路网中出租车数量与出租车起步价3种变量对准许空驶出租车使用HOV车道这一政策的影响。

To explore the impacts of the utilization of vacant taxis using HOV(high occupancy vehicle)lanes on traffic system,this paper investigates the spatial equilibrium of the taxi market with/without the access of vacant taxis to HOV lanes.It uses a combined variational inequality(VI)to describe the traffic system equilibrium built on the travel mode and route choice,and adopts the algorithm which combines the Gauss-Seidel decomposition technology with the MSA algorithm to solve the VI.The traveler can follow the Logit mode choice and user equilibrium on the network.The model and algorithm are applied to a numerical example,and proceed on the comparative static analysis by comparing the performances of the network with the various occupancy,taxi fleet-size,and the preliminary flag-fall price.The results show that allowing vacant taxis to use HOV lanes may cause the phenomenon similar to the Braess paradox and reduce social welfare,and the occurrence of this phenomenon depends on the parameters of the road network.Meanwhile,the effect of allowing vacant taxis to use HOV lanes is limited,which is basically caused by traffic flow distribution,while the oversaturation of HOV lanes rarely occurs.In addition,this paper also explores the impact of three variables,i.e.,the average occupancy rate per unit vehicle,the number of taxis in the road network,and the starting price of taxis,on the policy of allowing vacant taxis to use HOV lanes.