Beschreibung:
Traffic routes serve to interconnect different locations. At the same time they bisect a spatial area into two “sides” of the route. The paper orientates on the fragmentation effect: Inside urban areas, main traffic routes can segment urban space, whereby physical barriers arise depending on their type (road or rail traffic), width and height (elevated, surface or underground) as well as traffic volume. Functioning as barriers, main traffic routes impair the quality of life in adjacent areas. The focus of this study is not on emissions and pollution but on barrier effects leading to “community severance”. Methodological the principal transferability of the structural analysis of landscape fragmentation to urban space will be shown. The European Urban Atlas of the Copernicus Land Monitoring Service provides a starting point by providing geodata on land use for almost 700 city-regions (2012). For the purpose of spatial analysis, a polygon geometry of “urban area” is defined and constructed using Urban Atlas data. Classified roads and railway lines are selected from the Open Street Map. Twelve cities with contrasting structures from different countries were selected as case studies. The study proves that the fragmentation of the urban area by main traffic routes can be analysed and measured at a city-wide scale using the indicator effective mesh size. The results provide indication of the spatial cohesion of the urban settlement area, in particular for comparison between cities. For visualization and to better compare cities, the results can be illustrated by calculating a regular grid or network for an average size of unfragmented areas. The effective mesh size describes the degree of fragmentation of urban area and can be regarded as a metric largely independently of city size and density. Such a metric on a city-wide scale can be a supplementary information in the European Union’s Urban Audit.