Some regions have made these kinds of changes real. In Copenhagen, a city of 1.7 million people, road building was abandoned in the early 1970s, large numbers of bus priority lanes were introduced, and a comprehensive network of segregated cycle paths was built. The result was a 10 percent decrease in traffic since 1970 and an 80 percent increase in the use of bicycles since 1980. Approximately one-third of commuters now use cars, one-third public transport, and one-third bicycles. Had Copenhagen embarked on major highway expansions in recent decades, surely energy use and emissions would be far higher than they are today. Is this not relevant evidence that highway capacity expansion in metropolitan regions promotes environmental degradation?
Since the 1970s in Europe, Japan, Australia, and increasingly in the United States, traffic calming and traffic cell systems have been and continue to be developed to reduce traffic speed and capacity in central areas and residential neighborhoods. There is empirical evidence that these highway capacity reduction strategies typically also reduce air pollution emissions, noise, and energy use. Although mentioned in the report (Chapter 3), this evidence is not well-considered in the report's findings.
Traffic calming encompasses a wide range of techniques for slowing down motor vehicle traffic to provide an environment more supportive of walking and bicycling and safer for children, the elderly, and others. Traffic calming measures include narrowing roadways, reducing speed limits, introducing curvilinear elements in formerly straight streets to slow traffic, and changing the vertical profile of the street with elements such as raised intersection tables for pedestrian and