All of this adds up to more traffic jams. The way to measure road congestion is by figuring the percentage of roads near or at capacity during rush hour. Between 1975 and 1993, that number went from about 40 percent to 70 percent. Some people would say congestion is a reason to build more roads. If you think road rage is bad now, just wait a few years.
Motor vehicles are the largest single source of atmospheric pollution worldwide.
Sixty-five percent of all carbon monoxide emitted into the environment comes from road vehicles. Carbon monoxide, besides being poisonous, contributes to global warming by promoting the buildup of methane, a powerful greenhouse gas. And motor-vehicle air conditioners in the U.S. are the world's single largest source of atmospheric chlorofluorocarbons, which also destroy the ozone layer. First of all, I don't think that's going to happen, given the power and size of the oil and auto industries. For the time being, any policies that would curtail their massive government subsidies or in any way impede their profitability will never be enacted.