Enhancing accessibility through rail transit in congested urban areas: A cross-regional analysis

The efficacy of urban rail transit in reducing the impact of road congestion is the subject of debate in policy and academic communities. Despite huge challenges arising from multifaceted factors such as data limitation, the recently released annual average congestion data enables us to empirically analyze the effect of urban rail transits in terms of their contribution to the average accessibility under road congestion. This paper presents a framework to evaluate the accessibility improvement benefit of urban rail transit under road congestion from a mean-field perspective. A cross-regional analysis in 43 Chinese cities demonstrates that the rail transit networks enhance the potential accessibility and contour accessibility by up to 5.07% and 12.09%, respectively. Besides, the accessibility improvement benefit largely depends on the road congestion level, rail network size, and layout of rail network. Furthermore, simulations on randomly generated rail transit networks indicate that the population coverage and proximity to roads are two structural determinants on the performance of rail transit. The proposed framework, together with the empirical findings, provides insights for city authorities to plan urban rail networks.