Spatial-temporal coupling relationship and driving factors between transportation-environment-technology-economy:A case study of the Backward U-shaped Bend Metropolitan Area in the Yellow River Basin

The Backward U-shaped Bend Metropolitan Area (BUBMA) within the Yellow River basin holds significance as a pivotal metropolitan region, crucial to the national strategic advancement. Rapid advancements in transportation have substantially bolstered the high-quality progression of its economy. Concurrently, the evolution of transportation and economic expansion exert a discernible influence on the environmentally sustainable development of BUBMA. In this research, we scrutinized the spatio-temporal dynamics of the coupling coordination degree (CCD) among the Transportation, Environment, Technology, and Economic System (TETE system) and dissected the underlying driving factors by utilizing the coupling coordination degree model, the grey relational degree method and threshold regression model. The findings indicate a progressive ascent in the CCD of the TETE system within BUBMA, marked by diminishing regional disparities. Spatial autocorrelation analysis reveals a positive correlation encompassing the entirety of BUBMA, with most cities displaying cluster effects that align with neighboring cities. Notably, cities with high or low CCD are geographically proximate. Additionally, this necessitates heightened investments in transportation infrastructure construction, a steadfast commitment to low-carbon green governance, and expeditious formulation and enforcement of environmental regulations. Reinforcing the leadership role of provincial governments and fostering collective efforts is crucial in expediting the coordinated development of BUBMA. • TETE system's evolution in BUBMA were analyzed using CCD model and grey relation analysis. • CCD showed fluctuating growth, with L-L clusters in southern cities and H-H clusters in capital. • Transportation green intensification emerged as the key factor influencing the development of CCD.