Identifying polycentricism: a review of concepts and research challenges

Assessment of polycentricism is one approach to understand the process of urban expansion and its structural changes. The assessment is important to provide knowledge as a basis for future planning and policy. This review article structures the existing concepts of polycentricism, examines the methodologies applied for polycentricism assessment at different spatial scales and across world regions. Based on this, it identifies future research challenges. The review shows that studies of polycentricism have been conducted primarily in cities across the more developed world regions while in the developing world regions, fewer studies are available and only began to emerge in the 1990s, two decades later than the West. The reviewed studies use employment distribution and travel behavior as the primary sources of data. To compensate for the lack of well-documented employment distribution and mobility data, more diverse indicators and sophisticated digital-based approaches have been applied in the latest studies that focus on cities in developing world regions. The reviewed studies demonstrate for the examined cases a general shift towards polycentric development. While in the more developed world regions polycentricism is influenced by employment decentralization, in the developing world regions this phenomenon is influenced by market forces and spatial planning policies.