People are born almost equally mobile. Their natural ability speaks for the personal liberty of each one to go wherever he or she wants to go. Citizens of a society founded on the notion of equity will demand the protection of this right against any abridgment. It should be irrelevant to them by what means the exercise of personal mobility is denied, whether by imprisonment, bondage to an estate, revocation of a passport, or enclosure within an environment that encroaches on a person's native ability to move in order to make him a consumer of transport. This inalienable right of free movement does not lapse just because most of our contemporaries have strapped themselves into ideological seat belts. Man's natural capacity for transit emerges as the only yardstick by which to measure the contribution transport can make to traffic: there is only so much transport that traffic can bear. It remains to be outlined how we can distinguish those forms of transport that cripple the power to move from those that enhance it.
Transportation can abridge traffic in three ways: by breaking its flow, by creating isolated sets of destinations, and by increasing the loss of time due to traffic. I have already argued that the key to the relation between transport and traffic is the speed of vehicles. I have described how, past a certain threshold of speed, transport has gone on to obstruct traffic in these three ways. It blocks mobility by cluttering up the environment with vehicles and roads. It transforms geography into a pyramid of circuits sealed off from one another according to levels of acceleration. It expropriates life-time at the behest of speed.
If beyond a certain threshold transport obstructs traffic, the inverse is also true: below some level of speed, motorized vehicles can complement or improve traffic by permitting people to do things they could not do on foot or on bicycle. A well-developed transportation system running at top speeds of 25 mph would have allowed Fix to chase Phileas Fogg around the world in less than half of eighty days. Motors can be used to transport the sick, the lame, the old, and the just plain lazy. Motor pulleys can lift people over hills, but they can do so peacefully only if they do not push the climber off the path. Trains can extend the range of travel, but can do so with justice only if people have not only equal transportation but equal free time to come closer to each other. The time engaged in travel must be, as much as possible, the traveler's own: only insofar as motorized transport remains limited to speeds which leave it subsidiary to autonomous transit can a traffic-optimal transportation system be developed.
A limit on the power and therefore on the speed of motors does not by itself insure those who are weaker against exploitation by the rich and powerful, who can still devise means to live and work at better located addresses, travel with retinue in plush carriages, and reserve a special lane for doctors and members of the central committee. But at a sufficiently limited maximum speed, this is an unfairness which can be reduced or even corrected by political means: by grassroots control over taxes, routes, vehicles, and their schedules in the community. At unlimited top speed neither public ownership of the means of transportation nor technical improvements in their control can ever eliminate growing and unequal exploitation. A transportation industry is the key to optimal production of traffic, but only if it does not exercise its radical monopoly over that personal mobility which is intrinsically and primarily a value in use.