Impact of infrastructure investment on Chinese railway efficiency

Since 2000, China has significantly increased investment in railway infrastructure, particularly following the 2009 financial crisis. However, the effectiveness of such investment in improving railway efficiency has not been thoroughly assessed. To this end, this study uses a three-stage DEA model to evaluate the PFP and TFP of 18 railway bureaus from 2009 to 2020, analyzing the impact of infrastructure investment on railway efficiency across regions of China. Furthermore, a LightGBM regression model is employed to identify the key infrastructure factors influencing railway efficiency. We find that infrastructure investment significantly alleviates environmental heterogeneity and reduces efficiency disadvantages across regions. Efficiency improvements are primarily driven by network scale effects, as infrastructure expansion enhances network connectivity and enables railway operations to approach more efficient production scales. Moreover, the marginal efficiency gains from infrastructure investment are markedly stronger in low-efficiency regions, where infrastructure constraints are more binding. Feature importance analysis also reveals heterogeneous effects across different types of infrastructure inputs. Basic infrastructure components, including bridges, tunnels, and stations, play a dominant role in improving efficiency in low-efficiency regions, whereas infrastructure upgrading, particularly electrification and seamless tracks, has a greater impact in high-efficiency regions. These findings highlight the importance of differentiated infrastructure investment strategies, prioritizing network connectivity improvements in lagging regions while emphasizing infrastructure upgrading in more developed areas to promote balanced efficiency development within the railway sector.