One measure of a robust transportation system is the diversity of travel modes. US cities are dominated by a single mode: the private car. On average, each person in the US cities sampled in 1990 logged 10,870 kilometers (6,750 miles) of city driving more than a round trip across North America. Growth in car use in the US cities between 1980 and 1990 was 2,000 kilometers per person, nearly double the increase in the Canadian cities, which have the next highest driving level. In industrial countries, urban car use has tended to rise as population density has declined. US cities have led the trend toward dispersed, low-density development. Between 1983 and 1990, the average roundtrip commute to work in the United States grew 25%, to 17 kilometers (11 miles). As cities sprawl, cars become essential while transit , bicycling, and walking become less practical. Compact Asian and European cities thus have the highest levels of non-motorized transport.
As car use rises, car-related problems mount. Fatal crashes, for example, increase. The exception is cities in developing countries, where low car use is offset by poor signals and safety regulations. Nonetheless, highly car-reliant US cities exceed even developing Asian cities in per capital traffic fatalities. Worldwide, traffic accidents kill some 885,000 people each year—equivalent to 10 fatal jumbo jet crashes per day—and injure many times more.
[Key Words]
log v. 把……记入航海(或飞行) transit n. 运输，经过
jumbo jet 大型喷气式客机