2: Environmental Effects of Urban Traffic

This chapter starts with a general overview of environmental effects related to traffic followed by an overview of urban environmental effects. Effects relate to emissions of CO₂ (climate change), NO_x (acidification, air quality), PM, CO and HC (air pollution) as well as to noise production. It also gives an overview of the related health impacts. Attention is then paid to the health benefits of walking and cycling. Finally, this chapter focuses on possible measures to reduce negative environmental impacts.

Over the last four decades, the impact of transport on the environment has changed from a new subject to one that is now generally recognized as very important and that should play a key role in transport policies. In the late 1960s resistance of both the public and policymakers to large-scale reconstructions of central urban areas to provide more space for traffic (roads, parking places) started to increase, resulting in many plans being abolished. In the early 1970s many Western countries introduced regulations for the maximum emissions of pollutants per vehicle kilometre for cars and other road vehicles, to reduce negative health impacts. Later regulations for noise emissions were also implemented. The attention paid to environmental issues increased rapidly due to reports such as the first report of the Club of Rome (Meadows, 1972) and Our Common Future (WCED, 1987). In the mid-1990s the World Bank introduced a general framework for the evaluation of all kinds of developments and policies that consisted of three blocks: impacts on the economy, social impact and environmental impacts (Serageldin and Steer, 1994). This framework has been adopted worldwide for evaluation purposes, including the evaluation of transport policies. This illustrates that environmental impacts have now become a well-established impact category in the area of transport.