Geography Reference
In-Depth Information
areas. The number of cases of severe asthma continues to increase in the overall
population, especially among children. Low housing density makes it difficult to
increase the share of public transport. Despite increasing investments, bus, subway,
and tram stations only allow limited access to housing and jobs. Regular urban bus
service ceases to be profitable where there are less than 30 inhabitants per hectare,
tram service (light rail transit) where there are less than 50 inhabitants/ha and the
subway where there are less than 70 inhabitants/ha. According to Alain Bertaud
[BER 02], this makes the success of Smart Growth strategies, based on the precepts
of New Urbanism, unlikely in the short term due to the extensive time necessary to
erase the consequences of 60 years of unbridled urban sprawl.
Figure 7.5.
Home-work commute for several major cities,
broken down by type of transportation, 2000
Currently, very few metropolises have a high enough population density in even
a part of their city to promote the use of public transport (see Figure 7.5). This is the
case in New York, where nearly 25% of home-work commuting is done via public
transport, compared to 66% in cars, including carpooling. The rate of public
transport use falls to less than 10% in San Francisco, despite the relatively high
population density of the urban area (60 inhabitants/ha). This unusual situation is
explained by the fact that the city is divided into several urban centers, scattered
around the bay, and the actual city center, which is relatively small (122 km²), is
home to only 11% of the population of the metropolitan area. Public transport use is
lower than the national average in Los Angeles, as it is in Atlanta, where 93% of
home-work commuting is done by car, of which 13% is done by carpooling.
