This study constructs an integrated analytical framework combining a Tripartite Coupling Coordination Degree Model (TCCDM), the Tapio decoupling model, and the Generalized Divisia Index Method (GDIM) to investigate the dynamic interactions and driving mechanisms among urban transportation, economic growth, and carbon emissions in Shanghai from 2000 to 2023. The results indicate that the coordination degree among the three systems evolves through three distinct phases: initial imbalance, critical transition, and high-level coordination. A three-dimensional phase diagram further reveals a marked shift from a “low-development, high-emission” pattern toward a balanced, high-quality development trajectory. Decoupling analysis demonstrates that economic growth and carbon emissions, as well as transport development and carbon emissions, have achieved significant decoupling in recent years. However, an expansive negative decoupling between economic growth and transportation highlights emerging challenges in sustaining synergistic development. Decomposition via GDIM shows that the interaction between economic development and transportation has consistently contributed to emission reduction, often exceeding the independent effects of either system. These findings underscore the role of systemic synergy in driving the nonlinear low-carbon transition of megacities. Consequently, policy interventions should adopt an integrated approach that fosters deep collaboration between green transportation transformation and high-quality economic development to effectively achieve carbon neutrality goals.
Liu et al. (Fri,) studied this question.