The Study Of Dynamic Traffic Assignment Model Under Variable Message Signs Condition

With the continuous development of ITS in our country, more and more variablemessage signs are applied to the road network, in order to relieve the traffic congestioncaused by the increasing vehicles. Under normal conditions, the dynamic trafficassignment model does not take into account the situation of changing paths when thedrivers saw the messages of variable message signs. So, the general dynamic trafficassignment models are not suitable to the road network which has variable messagesigns and the study of dynamic traffic assignment models under variable message signscondition is very meaningful.First of all, we made some studies of the effect of variable message signs ondynamic traffic assignment models. In this way, we made some expansion in thelegibility of variable message signs and we studied the display and the specific layoutof variable message signs. Meanwhile, we got the better combination of the displayand the content of variable message signs and the better layout to improve thecompliance rate to the guidance instructions.Secondly, we made a survey of drivers’ route choice behavior under variablemessage signs condition to determine the value of the driver-induced compliance rate.So, the drivers’ path selection factors had been analyzed and we searched some datausing a questionnaire of drivers’ path selection. According to a statistical analysis ofthe survey results, established a cumulative Logit driver route choice model under theconditions of variable message signs. Applied the model to predict the probability ofthe driver path selection and established a cluster model. According to the establishedcluster model, we got the induce compliance rates when variable message signsshowed different road congestions levels.Thirdly, we made a study of dynamic traffic assignment models and analyzed theinfluence of the induce compliance rates to the dynamic traffic assignment models.And then, we establish an improved dynamic traffic assignment model: the inducecompliance rates were corrected to the links inflow rate constraint of the models;graded the road running conditions according to the level of service; improved theoriginal BPR function; established the dynamic traffic assignment model undervariable message signs conditions and conducted random analysis, given a detailed algorithm design.Finally, this paper selected Harbin local road network for simulating. Based on thelayout principles and pre-distance of variable message signs, add variable messagesigns into the appropriate locations of road network; following, dynamic trafficassignment simulations under the presence or absence of variable message signsconditions had been made and comparative analysis the road network allocation results,assessed the road network operating results by using of the average delay of roadnetwork.