The trans-European transport network has different effects at macro regional mezzo-regional and micro-regional level, and its effectiveness rises with the lower regional levels. Possible approaches to the trans-European transport network impact and effect survey and policy options have been pointed out. The importance of increased accessibility and mobility for regional expansion and for a more balanced and polycentric system of city networks has been underlined. Changes in the spatial organization utilization and structure of cities, as well as in social benefits and losses subsequent to impacts of trans-European transport corridor "X" section Belgrade-Niš have been analyzed. The new trans-European or major transport infrastructure does not per se create regional and urban system network development, although it can affect the conditions for the processes that create growth and development. The effects can be increased by co-ordination of measures of regional, spatial and urban policy, land use transport, environmental and other policies. The necessary measure is the introduction of spatial impact assessment as sartorial policy instrument for the large transport infrastructure plans and projects.