Peoplešs travel behaviour appears to be controlled by basic instincts, so deep we have no perception of them. Through them it is time that finally sets the coordinates of travel.
Man is a territorial animal with a protected homing place. As usual in such cases the dangers of being caught in the open are limited by instinctive exposure time limits. For man this is, in the mean, one hour a day. Consequently, the territory he can control depends on the speed he can manage.
For a walking man the speed is about 5 km/hr, and the territory spans about 2.5 km around his home (or 20 km2). Walled cities never exceeded that limit of 5 km diameter, even Rome, Marrakesh or Vienna. The basic personal territory defines strictly the organization of space. Agricultural villages always had about 20 km2 of territory around them.
Territory is a precious asset and there is an instinct to expand it. Larger territories, however, require larger speeds, because of the time limitation. This interprets why travel machines have always been at the center of folklore and technological interest. They provided a steady increase in mean speed of about 3% per year during the last 200 years. The very interesting story of the introduction of these machines and their infrastructures will be outlined and quantitatively modeled.
The good question is what is next. The potential for hypersonic flight and Maglevs, as speed extenders, will be discussed, and their potential to redirect human settlements into an Ecumenopolis à la Doxiadis.
