Lu, MengyuanPerez, Edgar JimenezMason, KeithLi, Max Z.2024-12-202024-12-202025-02-01Lu M, Perez EJ, Mason K, Li MZ. (2025) A hierarchical spatial and temporal optimisation of the air-high speed rail intermodal network. Journal of Transport Geography, Volume 123, February 2025, Article number 1040850966-6923https://doi.org/10.1016/j.jtrangeo.2024.104085https://dspace.lib.cranfield.ac.uk/handle/1826/23304Spatial and temporal coordination of air-high speed rail (HSR) intermodal networks is important to reduce emission, improve service, enhance efficiency, and reduce costs in the provision of air-HSR integration. This paper constructs a hierarchical optimisation model that first considers a spatial scope to solve the problem of route allocation and frequency choice which minimises total environmental, operational and passenger cost with a Mixed-Integer Linear Programming (MILP) model, based on a demand estimation for passenger trips between city pairs. Then, the second hierarchical level of the model considers a temporal scope to maximise connection opportunities between the resulting air and HSR networks using time windows to adjust frequencies with a Prescriptive Integer Quadratic Programming (PIQP) model. An application to a network of 40 cities in mainland China with both air and HSR transport service shows that the total emission of the network can be reduced by 22 %. Comparative analyses show that optimising for passenger costs favours increased air travel on medium- and long-haul routes, while an emissions-focused approach encourages a shift toward HSR for short and medium distances. Sensitivity analyses on carbon pricing further highlight the potential of gradual price adjustments to incentivise lower-emission modes without requiring additional HSR infrastructure.enAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/33 Built Environment and Design35 Commerce, Management, Tourism and Services44 Human Society3509 Transportation, Logistics and Supply Chains4406 Human Geography3304 Urban and Regional PlanningLogistics & TransportationArticle559934104085123