Classification of medium and small cities for the implementation of Low Emission Zones

Growing mobility within cities has led to an unacceptable increase in the negative externalities of transport. In order to reduce this negative impact, Low Emission Zones (LEZs) are being implemented; among other actions and objectives, they include some type of circulating restriction for vehicles to improve air quality. Given the differences among cities, and the great variety of measures that a LEZ may include, it is necessary to develop aids for choosing the most appropriate type of LEZ to be implemented. This study identifies groups of cities having similar geophysical and socioeconomic characteristics, as well as other traits related with the generation of negative impacts by transport. Our classification may be used to propose common policy guidelines —in some cases even specific proposals— for planning an adequate LEZ in each city group, or for other municipalities that could identify with a particular group.The study case is Spain. A total of 61 cities were considered, described by means of 11 variables. Cluster analysis was used to define the groups of cities, giving eight clusters; in view of their most relevant characteristics, different policy guidelines and actions could be put forth for the design of a particular LEZ for each group.