In addition to providing a conceptual background to the analysis of the mobility of passengers and freight, transport geography is an applied science relying on quantitative and qualitative methods. There is a growing complexity, and data requirements, for the four common models in transport geography. Each builds upon the other, implying, for instance, that the estimation of accessibility cannot be assessed without information about distance and that spatial interactions are derived from accessibility assessments. Transport geography enables empirically based representations of various dimensions of transportation systems. In addition, there are various methods of general use in transportation studies that are readily applicable in transport geography. Accessibility is a key element to transport geography, and to geography in general, since it is a direct expression of mobility either in terms of people, freight or information. Destination choice models are considered an extension of the gravity model, since they provide a wider range of factors that explain the assignment of spatial interactions.