Transportation technology as a determinant of urban growth
Samuelson, Robert Edwin
Master of Architecture
THESIS: that changing transportation technology helped determine the limit of maximum expansion of the city and that the physical characteristics of transportation have determined the pattern of growth to that limit. Population movements and growth have occurred in two stages: influx into the city and explosion to the suburbs. Transportation technology has advanced in two stages: centripetal, emphasizing a single center, and centrifugal, de-emphasizing one center. There is a correspondence between these stages of population and transportation change. The growth of cities occurs in cycles. In a cycle, the dominant mode of transportation sets a pattern of land use which determines later need for transportation, and so on, in a continuous cycle of cause and effect. Along a path of transportation, a stop creates a nodal pattern centered around the stop. If the distance between the stops is long, the nodes retain their identity. If this distance is short, the nodes evolve a linear pattern. Growth occurs primarily in the linear or nodal patterns. A third pattern, spread, results when the pace of growth is so rapid that growth occurs in units the size of the basic network or larger. The network is the sum of the paths of a mode of transportation. The growth of Philadelphia, Chicago, and Houston demonstrates that: increasing speed of means of transportation extends the boundaries of the city outward in proportion to speed, the dominant mode of transportation during a cycle of growth establishes its peculiar pattern for future growth, the patterns of urban growth can be categorized as "nodal", "linear", and "spread", and these patterns of urban growth are determined by the physical characteristics of transportation.