Investigating Subcontracting Partnership in Sustainable Urban Transportation System Design

This study investigates the role of subcontracting partnerships in enhancing collaboration and sustainability in urban rail transit system design, addressing the challenges posed by fragmented practices and environmental goals under China’s “Dual Carbon” policy. Using a mixed-methods approach, we integrate structural equation modeling (SEM) and factor analysis to identify critical success factors (CSFs) and their impacts on design performance. SEM, a statistical technique capable of analyzing complex relationships between unobservable “latent variables” (e.g., trust, innovation) and measurable outcomes, was employed to validate the hypothesized relationships among five key factors: Excellence in Quality, Interactive Collaboration, Collaborative Vision, Risk Strategy, and Strategic Innovation. Factor analysis consolidated 19 CSFs from the literature into these five constructs, explaining 69.09% of the variance. The SEM results revealed that Excellence in Quality, Interactive Collaboration, Risk Strategy, and Strategic Innovation directly improve design performance, while Collaborative Vision indirectly influences outcomes through mediating effects on risk management and innovation. These findings provide actionable strategies for leveraging BIM/blockchain tools and institutional frameworks to enhance sustainability in urban transportation projects. By contextualizing partnership dynamics within China’s state-led infrastructure ecosystem, this research enriches the theoretical understanding of partnership mechanisms.