Civil Engineering Reference
In-Depth Information
trip is by commuter rail, however, only jobs within 12 miles can be reached. Thus
the higher
door-to-door
travel speed of the automobile and its unlimited choice of
destination opportunities, make it possible for a commuter to expand her/his area of
residential location and job choices.
The motor vehicle allowed urban activities to spread-out by removing the need
to locate buildings within walking distance of rail stations, and reduced the reliance
on transit for accessing more distant destination opportunities. In the US, the
superior mobility provided by the automobile was quickly recognized and its
popularity steadily increased. In 1916 there were over 2 million automobiles owned
and that increased to 8 million in 1920
a fourfold increase in 4 years. Before the
beginning of WWII (1940), there were 32.45 million motor vehicles in the US.
After WWII, the private motor vehicle further accelerated the urbanization of
agricultural and developable land beyond the city
—
s limits. This was made possible
by the convergence of a number of factors. The construction of high-speed
(65 mph) limited access highways made possible by a vast federal road building
program that peaked with the Federal-Aid Highway act of 1956 authorizing 41,000
miles of high speed freeways and expressways which by 1972, were to link 90 % of
the cities with population of 50,000 population or greater, along with many smaller
cities and towns [
3
]. When combined with affordable prices of automobiles, cheap
gasoline, an abundance of FHA low-cost housing mortgages, and a favorable tax
code for home owners, these events set in motion a large suburban expansion of the
population into low-density housing developments that could only be served by car,
and were followed by the spreading of jobs from center cities into suburban areas
[
4
]. Schools, retail stores, industries also became more numerous in suburban
settings.
The popularity of the car as a mobility provider enabled vast number of families
to escape the city
'
with its crowded housing, poor public schools, high crime, and
racial problems of the 1960s
—
by moving to the open spaces and affordable larger
living quarters offered by the suburbs made accessible by new highways connecting
the new residential developments to the jobs in center cities. Modes of Travel in US
Metropolitan Areas.
Tables
2.1
and
2.2
show commuter trips within the US metropolitan areas and
the major travel modes used in commuting to and from work.
The signi
—
cance of Tables
2.1
and
2.2
can be summarized as follows:
(1)
In the suburbs, where 64 % of metro area commuters live and about 54 % work
(Table
2.3
), the car is used for 94 % of suburban trip destinations that originate
in center cities; 91 % of suburban trip destinations originating in the suburbs;
and 93 % of center city destinations originating in the suburbs.
(2)
In center cities, where 36 % of commuters live and approximately 46 % of the
commuters work, transit is used for 15 % of center city trip destinations
originating in center city; 6 % of center city trip destinations originating in the
suburbs; and 5 % of suburban trip destinations originating in center cities.
