Critical Surveys Edited by STEPHEN ROPER

Roca Cladera J. and Moix Bergada M. (2005) The interaction value: its scope and limits as an instrument for delimiting urban systems, Regional Studies 39 , 357-373. There is a long tradition of different approaches relating to the delimitation of urban systems, such as those pertaining to the delimitation of Statistical Metropolitan Areas and Daily Urban Systems, and Local Labour Markets. This paper is primarily concerned with the theoretical and practical interest of the concept of the interaction value, a notion found embedded in the methodology of travel to work areas used in the UK. The paper applies the interaction value to the delimitation of territorial systems in the spatial context of Catalonia, Spain, based upon patterns of commuting for employment purposes. The paper makes a call for a more integrated approach to the delimitation of urban systems, drawing upon the interaction value. This approach allows for the identification of hierarchical and diffuse interactions, characteristic of the internal structuring of metropolitan areas and urban systems.