Source: adapted from Muller, P.O. (1995) "Transportation and Urban Form:
Stages in the Spatial Evolution of the American Metropolis". In Hanson,
S. (ed.) The Geography of Urban Transportation, 2nd Edition, New York:
Guilford, p. 29.
Evolution of Transportation and Urban Form in North America and
Europe
Both North American and European cities have been modified by similar
technological changes introduced since the industrial revolution. However,
a different evolution of urban form has occurred, especially from the
second half of the 20th century. While European cities leaned on public
transit, North American cities relied more on the automobile. This evolution
had a direct impact on the urban form with four important periods in
the evolution of urban transportation that can be identified:
- I - Walking-horsecar era (1800-1890). This era was characterized
by the absence of urban mass transportation. People had access to
locations that could be reached (walked) in less than 45 minutes
(4 to 6 km). Urban densities were very high as the available space
was strongly constrained by accessibility. All economic activities
were concentrated in a central node along with residential areas.
Reduced mobility (pedestrian area) accounted for this concentration.
The horsecar made its debut in this period, which allowed the development
of corridors. From the 1850s, railways enabled radial development
adjacent to railway stations, especially in Europe and in older
American cities (e.g. New York).
- II - Streetcar era (1890-1920). The development of the
first forms of urban mass transportation lessened the accessibility
constraint and enabled cities to expand along main tramway (streetcar)
lines, creating transit corridors. In tripling the speed of urban
transport, electric streetcars expanded the spatial structure of
cities. This permitted the emergence of a specialized downtown area
with commercial and service activities. In Europe, tramway lines
tended to expand towards long established adjacent towns, which
were swallowed and integrated in the expanding city. This allowed
the development of urban activities beyond city limits. The emergence
of commercial centers along transit corridors became apparent because
more and more people, having access to trolleys, decided to relocate
outside the city limits. This reinforced social stratification and
favored the emergence of neighborhoods differentiated by socioeconomic
status. Less fortunate people, limited in their mobility, tended
to remain in central areas while the wealthier class relocated in
the first suburbs. The first suburban railroads entered in service
and specialized industrial districts started to take shape.
- III - Automobile era (1920-1945). Motorized transportation,
mainly buses and cars, radially expanded cities, once again lessening
the accessibility constraint. Never a technical innovation had a
greater impact on spatial organization than the automobile. Initially,
only wealthy classes could afford their own automobiles which were
used mainly for recreational purposes. The private car was linked
with the emergence of the firsts low density suburbs with increased
ethnic and economic segregation. This went on par with the decentralization
of commercial and industrial activities. It is during this phase
that European and North American urban development started to diverge.
In order to facilitate the diffusion of the road as a mode of urban
transportation in the United States, several oil and car companies
bought and dismantled tramway systems. For instance, in 1938 General
Motors and Standard oil bought the Pacific Electric Railway of Los
Angeles, dismantled it and replaced tramways with buses. Consequently,
the influence of streetcars in the urban development in North America
was being removed, while it endured in many European cities.
- IV - The highway era (1945-2000). The post World War
Two era saw the large diffusion of the automobile with a growth
of individual mobility. Highways favored the extension of full fledged
suburbs, especially in North America. This process also took place
in Europe, but to a lower extent and involved higher densities along
existing transit corridors. No significant new urban transit technologies
emerged during this era, but improvements in transport infrastructures
significantly increased accessibility. Residential and employment
decentralization was thus accentuated. Also, several sub-centers
emerged to serve suburbs, a process favored by the construction
of ring roads around metropolitan areas. The development of new
highways which circled urban perimeters have encouraged an agglomeration
of commercial, distribution and manufacturing activities around
high accessibility clusters in suburban areas.
The 21st century is bringing several issues about the future relationships
between transportation and the urban form. In the era of telecommunications
a decline in individual mobility and a concentration of activities along
transport corridors can be expected, especially in North America. This
process will be correlated to higher prices for individual mobility
as well as attempts at substituting telecommunications to transport
in several sectors of activity, notably tertiary and quaternary sectors.
Future urban forms are thus likely to be of higher densities with a
concentration around clusters. Yet the impacts of telecommunications
on urban mobility and urban form remains to be assessed.