The following is from the book, "Ecology of Commerce" by Paul Hawken.

Consider another situation ripe for green taxes: road congestion. In the San Francisco Bay Area, after decades of building freeways and bridges, the average speed of travel is 15 miles per hour during rush hour. In southern California, it is considerably less. Hardly a person who sits in a traffic jam has not considered the costs involved in fuel, time, and stress. The World Resources Institute estimates that Americans pay an extra $300 billion per year in expenses directly related to our over-reliance on the automobile. One study estimates that by 2005 Americans will waste almost 7 billion hours a year sitting in stopped traffic, at a cost of over $75 billion. Add to that the extra fuel use of 7.3 billion gallons and wear and tear on autos, and another $40 billion is lost. Accidents increase in tied-up traffic, adding to the yearly bill some $275 billion in vehicular damage and medical costs. These figures do not take into account the effects of smog, acid rain, or personal stress.

Rush-hour commuters on congested highways are participating in a market system that does not fully reflect these costs. In fact. it would be hard to design a less efficient "market" than the present urban interstate system, precisely because, again, the true costs of traffic stoppages are externalized throughout society. If tolls were placed on highways to account for these costs, automobile usage would drop, traffic patterns would change, revenues would increase, and congestion would be reduced.