Where Station-Area Effects Really Peak: Donut Gradients, Temporal Displacement, Spatial Dependence, and Vertical Walkability in Taipei, Seoul, and Tokyo

This conceptual and methodological synthesis examines why the location of the strongest station-area response is not stable across mature metro cities. Instead of estimating a pooled East Asian transit premium, it uses peer-reviewed evidence and official urban and rail indicators for Taipei, Seoul, and Tokyo to clarify how peak location depends on outcome type, project timing, spatial dependence, submarket structure, and station-front pedestrian integration. The Taipei evidence reviewed here is used to examine a temporal-displacement mechanism; the Seoul evidence reviewed here to examine a spatial-confounding mechanism; and the Tokyo evidence reviewed here to examine a core-reintegration mechanism. These are case-dominant mechanisms identified from the reviewed evidence, not exclusive labels for every station in each metropolitan system. The synthesis separates three layers: models estimated in the cited studies, transparent calculations performed in the present manuscript, and modeling templates proposed for future harmonized comparative research. It further specifies how vertical walkability can be measured through multilevel circulation, barrier-free access, entrance permeability, weather-protected continuity, transfer directness, and plaza legibility. The contribution is therefore to develop a comparative framework for identifying edge-centered, donut-shaped, model-sensitive, and re-centered station-area gradients, and for clarifying how different forms of evidence can inform the analysis of peak location across mature metro systems.