Zooming in and out of compact urban centers in a rapidly developed metropolis: A multi-scale investigation through isobenefit lens in Seoul

Compact city policy in rapidly developed metropolitan areas increasingly emphasizes balanced urban development. Cities like Seoul have pursued the balanced distribution of livability opportunities by expanding public transport networks and promoting multiple socio-economic hubs at key transit nodes – so called compact multi-centered urban policy. However, critical evaluations of whether and how such models fully achieve their intended outcomes, especially essential service and infrastructure across diverse localities remain limited. Aligned with the concept of isobenefit cities , this research develops and applies a Multi-Scale Investigation (MSI) as an integrative evaluation tool to assess social outcomes from compact multi-centered cities. Specifically, the MSI framework holistically investigates two interrelated dimensions: local service accessibility and city-wide connectivity by public transport, by “zooming in and out” socio-economic centers located at strategic nodes across a city. We applied this framework to evaluate varied Centers across the Seoul Metropolitan City, an exemplar of rapid urban growth and a compact polycentric urban policy. The MSI analysis revealed that while all selected centers exhibited strong city-wide connectivity, local service accessibility often fell short of expectations, primarily due to negative local-scale effects such as limited service diversity constrained mobility. Differences across varied center typologies were particularly noteworthy. The Central Business District (CBD) exhibited the highest level of city-wide connectivity but the lowest local accessibility, indicating a pronounced imbalance. The Quarter Center scored the lowest overall, suggesting its limited role as a hub of the quarter area. In contrast, the District Center achieved the highest MSI result, reflecting relatively stronger local outcomes. The MSI analysis exposes scalar tensions embedded within the isobenefit assumptions when applied to rapidly developed metropolitan contexts. Our research underscores that achieving a balanced distribution of urban benefits requires multi-scalar approaches that incorporate distinctive, yet flexible measures tailored for the functional roles and spatial conditions of different center typologies.