渋滞
Traffic congestion, especially at rush hour, is a problem in many of the country's larger cities. A 2009 study found that traffic congestion costs the United States almost $87.2 billion. The economic costs of traffic congestion have increased 63% over the past decade, and despite the declining traffic volumes caused by the economic downturn, Americans still waste more than of fuel each year as a result of traffic congestion. Motorists also waste 4.2 billion hours annually, or one full workweek per traveler. Moreover, it is estimated that drivers are wasting 6.9 billion hours per year or about 42 hours per driver in traffic congestion as a result of aging infrastructure and poor road conditions.