A review on research regarding HSR interactions with air transport and outlook for future research challenges

The interactions between high-speed rail (HSR) and air transportation systems constitute a complex, evolving integral component of our modern transportation landscape. Over recent decades, changes in travel patterns and growing environmental concerns, spurred by advancements in railway technology, have significantly influenced the dynamics of these two transportation modes. While previous reviews on this subject have provided seminal insights, there is a necessity for a novel synthesis of research findings in recent years, given that extant reviews have covered the evolving landscape until the year 2018 only. This review critically evaluates the latest literature to analyze five aspects regarding air/HSR interactions: Modal integration/modal competition, bi-directional impacts, emission aspects, robustness/resilience perspectives, and some other related work. In addition, we propose a set of ten challenging research questions, highlighting the need for concerted research efforts, considerations of more practical decision factors, and evidence-based policy making to foster a sustainable and resilient integration of air/HSR systems in the 21st century.