Assessing the Functional Polycentricity of the Mega-City-Region of Central Belgium Based on Advanced Producer Service Transaction Links

H<sc>anssens</sc> H., D<sc>erudder</sc> B., <sc>van</sc> A<sc>elst</sc> S. and W<sc>itlox</sc> F. Assessing the functional polycentricity of the mega-city-region of Central Belgium based on advanced producer service transaction links, <italic>Regional Studies</italic>. This paper comments on three aspects of POLYNET's implementation of the Globalization and World Cities (GaWC) model to measure functional polycentricity at the local scale. These aspects are: (1) the use of advanced producer services (APS) office locations as a proxy for inter-city relations, (2) the problematic calculation of the functional polycentricity index, and (3) the narrow conceptualization of functional polycentricity. Alternative methodologies based on transaction link data are introduced to examine whether Central Belgium displays features of a functionally polycentric mega-city-region. The results suggest that this is not the case: Central Belgium displays more features of a hierarchical urban system with Brussels as the dominant service city. However, some indications are found for a preliminary urban network formation.