Source: adapted from Schafer, A. (2000) Regularities in Travel Demand: An International Perspective, Journal of Transport Statistics, Vol. 3, No. 3.
Distance remains a significant factor in the modal choice of passengers. The above figure represents the respective share of three modes by travel distances and excludes public transit and rail. It underlines two significant travel distance thresholds. The first is the 30 minutes walking threshold, representing about 2-3 kilometers beyond which the average person is unwilling to walk. However, in a motorized society such as the United States, the automobile plays a significant role in short distances. This is associated with the urban physical setting, which is less suitable for walking and involves lower densities and fewer sidewalks. The second is the 1-day driving threshold, at about 700-800 kilometers, which is equivalent to about seven or eight hours of driving. Beyond this point, air transportation clearly dominates and becomes the only possible mode for distances of more than 8,000 kilometers.