Transportation Geography and Network Science/Modal selection
Network technologies, including modes affect the optimal network geographical and topological arrangement. The optimal mode depends on market size and distances.
This figure 'Autos, Trains, and Planes', which is standard in transportation economics or geography, shows the "optimal" mode for a particular distance. For short distances the lower fixed costs of making an auto trip outweigh its slower running speed. At longer distances, the high fixed access costs of airplanes are compensated by a faster travel times. Trains are historically in the middle. A similar graph applies to freight, just change the modes to Autos to Trucks, Passenger Trains to Freight Trains, and Planes to Ships. The question is whether there is a range between d1 and d2, that is, does rail actually dominate both autos and planes over any region. In terms of travel time it probably does, and looking only at operating cost, it might. In terms of overall cost, including the fixed cost of construction of a new HSR line, it probably does not under current cost structures. The size of this range, if it exists, is, however, empirical, and subject to change with costs and technologies.