Informal Utilization Characteristics of Underpass Public Spaces in Megacities from the Perspective of Co-Production Theory: A Case Study of Elevated Highway Underpasses in Guangzhou

Abstract

Under the guiding principle of “People-Oriented Urban Development,” public space has become a core focus of urban development in China. As major cities enter a stage of stock-based urban regeneration – emphasized repeatedly at the national level, notably in the 2025 State Council meeting – the potential of under-bridge spaces as public space assets in megacities has garnered significant attention. However, formal regeneration approaches often face prolonged implementation cycles due to complex land rights and the involvement of multiple management departments. In contrast, the informal use of under-bridge spaces (e.g., temporary markets, sports grounds) is widespread yet understudied in large Chinese cities. Based on co-production theory and adopting a socio-spatial perspective, this study investigates multiple cases of informal under-bridge space utilization in Guangzhou, a representative Chinese megacity. The research aims to systematically summarize the core characteristics of such informal use (such as spatial adaptability, actor diversity, and functional dynamics) and reveal the interaction mechanisms among diverse actors in the informal production of space. The findings offer theoretical insights and practical references for overcoming the challenges of formal regeneration and exploring more inclusive and adaptive governance models for under-bridge spaces in megacities within the context of urban renewal.