Research On Vehicle Fuel Consumption In The Urban Transportation System

It goes without saying that the urban transportation brings forth the urban economy and social development, improves people's mobility. But there exist some negative effects while we should pay close attention to. These negative effects include energy consumption, environment polluting, traffic accidents increasing, etc. So the urban transportation development concerns is not whether or not we should foster the vehicle transportation development, but how to develop it, how to regulate the development while restricting its disadvantages in reasonable scope. Vehicle fuel consumption is a systematic and complicated aspect in the urban transportation system. Some of it attributes to the characters of vehicle, others relates to the road and traffic condition, still others seem to stress the evaluation methods of it. Based on the project supported by National Nature Science Foundation, "Research on the Sustained Urban Transportation Development System", this dissertation systematically illustrates the analysis and forecast methodologies of vehicle consumption in the urban transportation system. To evaluate the fuel consumption in various road and traffic condition, some appraisal indexes which concern about the efficiency of fuel usage, fuel consumption level, vehicle type, road type, traffic flow, etc, are brought forward in the dissertation. Vehicle fuel consumption is analyzed thoroughly from micro-and macro-scope. The micro-theoretical model is constructed according to engine experimental data with the use of power equilibrium theory, and has high precision. This model can be used to analyze how the fuel consumption is affected by the factors such as engine running speed, engine power, road grade, decelerating-accelerating process, accelerating-sliding process, vehicle speed, and carrying load, etc. Based on the field data, the macroscopic forecast models are regression models. There are many factors have influence on the fuel consumption. To simply and accurately simulate the fuel consumption in the real traffic situation, the field data is dealt with cluster method, and the best indexes relating to the fuel consumption are picked out in the dissertation, the results are satisfactory. Not only can the macroscope models be used to predicate the fuel consumption in the practical environment, but also when combined with the traffic flow theory analysis, the road link and intersection fuel consumptions and the distribution of the fuel consumption in the urban transportation network can also be simulated. There exist great differences between every type of vehicles. To simplify our research work, three typical vehicles widely used in China are selected to represent three types of vehicles, such as light vehicle, middle vehicle and large vehicle. The fuel consumption of every type of vehicles can be reflected by the fuel consumption indexes of representative vehicle. The passage car equivalent proposed according to fuel consumption in the dissertation can be used to compare the fuel consumption between every types of vehicle under practical road (such as road link, intersection). Intersection is bottleneck of urban transportation network; it's also the most concentrated fuel consumption zone. Through an example analysis, the analysis method and procedure of intersection fuel consumption are proposed in the dissertation. In the general traffic planning and designing theory, the appraisal on road operation quality is limited to operation parameters (delay, saturation degree, speed, etc), but other parameters such as fuel consumption level, environment pollution degree, land use efficiency which have close relationships to the sustained urban transportation development, are passed beyond consideration. A synthetic method to evaluate the quality of road operation is given according to the fuel consumption indexes, in cooperation with the traffic operation ones. The standards to classify the levels of service of road-link and intersection are also provided.