交通网络中用户均衡行为的效率损失上界

确定交通网络用户均衡行为效率损失的上界是当前国际上的一个研究热点.深入分析了固定需求的交通网络中用户均衡与系统最优之间的关系,通过引入一个与均衡流量相关的参数,得到新用户均衡行为效率损失上界计算公式.算例结果表明,新的上界比目前文献报道的最低值还小.得到一个具有普适性的结论,即发现更小的用户均衡行为效率损失上界须涉及对象网络的所有特征,包括路段阻抗函数的特性、网络结构和交通需求水平.

Upper bounds of efficiency loss for user equilibrium behavior in traffic networks

Determining the upper bounds of efficiency loss for user equilibrium behavior in traffic networks has become a hot topic.The relationship between user equilibrium and system optimum flow patterns was explored in traffic networks with fixed demands.New formulae for computing the upper bounds of efficiency loss caused by user equilibrium behavior were derived through introducing a parameter associated with the user equilibrium flow pattern.Numerical examples show that the new formulae can give lower values of the upper bounds than those reported in literature.It is also concluded that finding more accurate upper bounds has to be connected with all characteristics of the studied networks,including the link cost functions,the network configurations and the travel demands.