I just stumbled upon an Oct '97 Scientific American article, by A. Schafer & D. Victor (pp. 58-61) on "The Past and Future of Global Mobility." The article, minus some graphs: http://www.sciam.com/1097issue/1097schafer.html . They make forecasts out to 2050 which, suprisingly enough, I find believable.
The main reason one might forecast out so far is that transportation infrastructures take a long time to change, and there are some robust relationships to build on. Across diverse societies, transportation time seems to take a bit over an hour per day, and distance travelled seems to be roughly linear with income. People in poor countries spend about 3-5% of income on bikes & buses, and this fraction rises till it stabilizes at 10-15% of income when there is about one car per five people.
It seems that the future of tranport is airplanes, which by 2050 should take 12 minutes per day on average in the U.S., and account for 41% of world distance traveled. (Buses would account for 20%, and cars 35%.)
The same issue also contains a reasonable skeptical take on telecommuting, at http://www.sciam.com/1097issue/1097mokhtarian.html .
Robin Hanson
hanson@econ.berkeley.edu http://hanson.berkeley.edu/
RWJF Health Policy Scholar, Sch. of Public Health 510-643-1884
140 Warren Hall, UC Berkeley, CA 94720-7360 FAX: 510-643-8614