How Urban Form, Scale, and Residential Behavior Jointly Shape Commuting Distance: A Controlled Simulation Experiment

Understanding how urban spatial structure affects commuting distance is critical for optimizing land use and promoting jobs–housing balance. While previous studies have examined this relationship through cross-city comparisons, few have quantitatively separated the main and interaction effects of urban scale, centrality intensity, and residential behavior under controlled conditions. Employing a controlled simulation, we constructed abstract grid-based cities across a broad size spectrum and systematically varied centrality intensity, central function type, and residential pattern. Results show that the designated residential pattern qualitatively alters the scale–commuting relationship. Relative to random residence, proximity-based residence reduces commuting distance by up to approximately 91% under the mixed monocentric structure and by approximately 87% under the employment-only center structure, both at low centrality intensity and large urban scales, reflecting the interaction between the allocation rule and urban form. Simulations further reveal a spatial mismatch trap: without coordinated residential agglomeration, employment centralization lengthens rather than shortens commuting for proximity-seeking residents, with penalties amplifying markedly as urban scale increases. Critically, jobs–housing spatial congruence, not centralization or decentralization per se, determines commuting efficiency. Under proximity-based residence, the mixed monocentric structure achieves shorter commuting distances than employment-only centers; in the proximity-based mixed scenario, the marginal commuting benefit of increasing centrality intensity declines at high intensity. These findings offer implications for land use and transport planning, particularly the need to couple employment centers with housing supply and prioritize residential proximity over morphological decentralization.