基于网络等级特征与VMS的交叉巢式Logit模型

A Modified Cross Nested Logit Route Choice Model Based on Network Hierarchy and VMS Information

基于等级特征与可变信息板(VMS)研究了交叉巢式Logit(CNL)模型及网络交通流分配。综合幂函数与指数函数表示方法给出新的信息效用衰减因子,结合道路等级特征表示VMS对车流的影响系数及CNL模型的分配系数;给出等级结构道路网络的随机用户均衡条件下的交叉巢式Logit路径选择模型及其等价数学规划,并设计网络流分配算法。通过实例网络的计算与分析,得到一些有意义的结论:等级结构越显著的路网总出行时间费用越低且其分散参数(θ)弹性绝对值越大;对具有较强随机性的实际路网,若增加一定的确定性则节省更多网络总出行时间;道路网络中设置了VMS时总出行时间受分散参数的影响更小。

Network traffic assignment and cross-nested Logit（CNL） model are investigated based on road hierarchy and VMS information. Supposing some main roads are installed with VMS equipment, the impact coefficients on traffic flow by VMS and the allocation coefficients in CNL model are calculated with road grade and a new attenuation factor of information utility that is formulated by integrating power and exponential ones. For hierarchical road network, CNL route choicemodel and its equivalent mathematical programming are established under the stochastic user equilibrium, and then a network flow allocation algorithm is proposed. The model and algorithm presented are examined with an example network. Calculations and analyses lead to some meaningful conclusions. The more significant hierarchical structure of road network, the lower the total travel time and the greater the absolute value of its elasticity on the diffusion parameter （O）. The enhancement ＇ of determinacy of the real road network that has relatively strong randomness will save more travel time. The road network installed with VMS is more slightly affected by dispersion parameter when the performance is measured by total travel time.