Source: Adapted from P. Hugill (1995), World Trade since 1431, Baltimore: The Johns Hopkins University Press, p. 213.

One Hour Commuting According to Different Urban Transportation Modes

There is a relationship between the form and structure of cities that was shaped by subsequent changes in transportation technology, which can be expressed through commuting range:

• Walking. Assuming a willingness to commute for one hour, a pedestrian walking at 5 km per hour could cross about 5 km. The space / time relationship of such a commute would be a circle of 10 km in diameter. This explains why prior to motorization cities were compact since most of the mobility took place by walking.
• Streetcar. A streetcar, like those operating in the first half of the 20th century, could travel around 15 km per hour along fixed lines. In this case, the space / time relationship would be star shaped to reflect walking to the streetcar line and of 15 km of diameter along the lines.
• Cycling. The bicycle became a mode of mass transportation in the late 19th and early 20th centuries. With approximately the same speed of a streetcar, but with no fixed line limitations, the space / time relationship of commuting by bicycle would be a circle of 15 km of diameter.
• Driving (no freeways). With a driving speed of about 30 km per hour (taking into account of stops, lights, congestion and parking), an automobile creates a spherical space / time relationship of about 30 km in diameter.
• Driving (with freeways). Along a freeway, a fixed infrastructure, the driving speed is doubled to 60 km per hour. The space / time relationship is then star shaped with 60 km of diameter along its axis.