The heterogeneous treatment effects and joint effects of high-speed rail construction and low-carbon city pilot policy on urban economic resilience

• This study presents a strong theoretical basis for empirical research by employing the theoretical framework established by New Economic Geography and general equilibrium analysis. • This paper is to comprehensively comprehend the synergistic effects of HSR development and LCCP policy on UER. • Regarding heterogeneity analysis, the main emphasis we place using the causal forest approach is on three dimensions: (i) disparities in policy impact among individual cities; (ii) diverse effects resulting from various stages of policy implementation; (iii) the factors that contribute to variations in policy impact. This study employs the causal forest and Difference-in-Differences methods analyze the joint effects and heterogeneous treatment effects of high-speed rail (HSR) development and low-carbon city pilot (LCCP) policy on urban economic resilience (UER). Grounded in the theoretical framework of new economic geography, the research conducts an exhaustive examination of general equilibrium. Empirical findings demonstrate a synergistic effect resulting from the concurrent implementation of both policies in bolstering UER. Additionally, the causal forest method is explores the heterogeneous treatment effects from spatial, temporal, and attribute dimensions. The study findings reveal significant differences in the effects of implementing either the HSR or LCCP policy across cities. The influence of HSR inauguration is most pronounced during its introduction in 2008, with diminishing effects over time, while the effectiveness of LCCP policy implementation in 2017 is comparable to that in 2012. HSR inauguration demonstrates a more substantial impact on cities with higher levels of urbanization and governmental involvement, while the LCCP policy has a more pronounced effect in cities with higher population density, increased governmental intervention, and a larger share of economic activities. Finally, the industrial structure poses an impediment to the promotion of UER by both HSR development and LCCP policy.