Effectiveness of traffic management measures in improving air quality in European cities

Motor vehicle emissions are the principal cause of a growing number of cities in Europe experiencing poor air quality. This paper examines the air quality effectiveness of selected traffic management measures implemented in European cities. Traffic management measures attempt to reduce total vehicle emissions by creating situations where vehicle engines operate efficiently, by eliminating congestion and smoothing traffic flows. They attempt to reduce the use of private vehicles by encouraging a modal switch from cars to public transport, cycling and walking and by applying measures to minimise the distances between home, work, shops and leisure facilities. Factors influencing the choice and the effectiveness of traffic management measures are discussed such as economic considerations, attitudes of the public, national constraints, and alternative goals for such measures (e.g. lessening congestion in order to improve mobility; reducing motor vehicle accidents). This paper highlight that there are a limited number of assessments available concerning the air quality effectiveness of specific measures in a variety of urban settings. One problem experienced in studies attempting to assess the air quality impacts of traffic management schemes is that rarely is one measure implemented on its own, rather a combination of complementary measures is introduced.