When rail matters most: policy impacts in China's freight "Modal shift from road to railway"

Given the prevalence of excessive overloading in road freight and its associated environmental impacts, rail has become an increasingly ideal mode of freight transport. The Chinese government implemented the "modal shift from road to railway" policy to redirect bulk cargo transport from roads to railways. This study employs a causal forest approach to evaluate the policy's effects, revealing that it reduced transport costs by 12 %, eased road congestion by 4 %, improved traffic safety by 3 %, and mitigated environmental pollution by 23 %. The policy's effects exhibited regional heterogeneity, particularly on the southeastern side of the Hu Line (China's demographic divide). Furthermore, the present study adopted the partial dependence plots to assess the marginal effects of key drivers. Notably, in regions with a railway mileage of approximately 2320 km, continued expansion of railway infrastructure generates disproportionately high marginal benefits, suggesting an important policy window when rail matters most. The results offer evidence-based guidance and a replicable framework for implementing freight modal shift strategies in developing countries, emphasizing the importance of regionally differentiated policies.