Modeling and application of metropolitan transportation support capacity

A macroscopic model was established to measure the support capacity of a metropolitan transportation system. The model consists of three modules; the road network, fuel consumption and atmospheric environment capacity. A novel concept, vehicle on road (VOR), was proposed in this study to better describe the support capacity, which means the instant number of the on-road vehicles at a certain average velocity; and the larger the VOR, the greater the environmental pressure. The model was validated and demonstrated to analyze the metropolitan transportation system in Beijing. The results showed that, at an average vehicle velocity of 23km·h^-1, the VOR in Beijing is 453500, including 297300 cars. Thus, over-loading traffic volume is the challenge facing the transportation system in Beijing. The model and VOR can play a central role in reflecting the relationships among the resource, the environment and transportation in metropolitan areas.