Regional accessibility impacts of integrating high-speed railway and conventional rail: spatial analysis of the Mumbai Ahmedabad region, India

The high-speed rail (HSR) significantly improves the accessibility between cities. However, these benefits are not uniformly distributed in the region that HSR connects. This study hypothesises that integrating the conventional rail network with HSR can improve regional accessibility and reduce HSR-induced inequity in accessibility. The scenario-based analysis was conducted to test the hypothesis on India's upcoming HSR corridor. The numerical results were obtained using weighted average travel time, potential accessibility, daily accessibility and area coverage as the indicators of accessibility. The introduction of HSR reduces inter-regional travel times by 45% but increases the inequity in accessibility by 19%. HSR's integration with conventional rail results in a 53% reduction in travel time and only an 8.5% increment in inequity. The HSR-integrated conventional rail's average speed improvement by 30 km/h improves the daily accessibility by 79% while reducing the HSR-induced spatial inequity by 13%. This study quantifies the accessibility and equity gains of integrating HSR with conventional rail and suggests intermodal cooperation for equitable and sustainable development.