Road Network Accessibility Based on Time Impedance Function

The concept and application scope of accessibility in the different disciplines were elaborated; the quantification method used commonly at the present stage was summarized; and application conditions and insufficiency of the usual model were pointed out, including gravity model, the distance model, and the accumulation opportunity method. Furthermore, it was discovered that quantification limited to the spatial criteria cannot respond to the relation of the spatial network accurately, in the view of this question, the quantification model was proposed on the basis of time impedance function, which takes the main variable by real capacity. This model can respond the spatial demand intensity indirectly. Then, the paper was to introduce the node importance concept, which can reflect factors influencing accessibility in road network even more directly, such as society, economy, transportation. This model can make up for the insufficiency of space and time method.