| The vehicle emission is the main reason causing urban environmental pollutions. Manyscholars have done a lot of researches about the estimation of vehicle emissions, but most ofthem were based on single-car and single-point estimation method. According to the previousachievements, this paper puts forward an estimation model of vehicle emissions focusing onroad network which is based on urban dynamic traffic assignment to compensate for theinadequacies of these estimation methods.Around this problem, this paper introduces a kind of dynamic network loading modelencapsulates Newell’s simplified kinematic wave model to complete the dynamic assignmentof traffic flow in the urban road network. Corresponding to the model, this paper also presentsa predictive dynamic users equilibrium condition and a convergent MSA algorithm based onsearching the shortest path. Subsequently the paper gives a curve model of vehicle airpollution emission factor and gross amount of vehicle emissions output estimation modelwhich is coupled with the dynamic traffic network model. When it comes to the emissionsmodel we should calculate the emissions output in links of the network that is determined bytraffic flow, the length of link and vehicle air pollution emission factor.The dynamic traffic assignment software called DTALite is used to simulate the model inthis paper. Through the analysis of simulation data, we obtain a conclusion that the grossamount of vehicle emissions in the road network is progressively increased with the ODdemand in the road network and the result verifies the validity of the model used in this paper. |
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