Real-Time Intermodal Substitution: Strategy for Airline Recovery from Schedule Perturbation and for Mitigation of Airport Congestion

Document Type

Journal Article

Publication Date


Subject Area

land use - planning, policy - congestion, place - airport


Surface transportation, Strategies, Strategic planning, Schedules, Recovery from delays, Real-time intermodal substitution, Programming (Mathematics), Priorities, Perturbations, Optimization theory, Objectives, Mathematical programming, Land transportation, Hubs, Hub and spoke systems, Ground transportation, Goals, Decision making, Congestion mitigation, Algorithms, Airport congestion, Airlines, Airline industry, Airline delays, Air lines, Air carriers


A strategy for airline recovery from schedule perturbation caused by adverse weather or other temporary events is proposed. Capacity reduction at a hub airport caused by these temporary events is reflected as reduced slots (or later controlled time of arrivals) for airlines from ground delay programs. It is suggested that under severe circumstances legacy airlines with hub-and-spoke networks implement ground transportation into their network to substitute for flights. This strategy is called real-time intermodal substitution (RTIMS). RTIMS is different from air–rail cooperation practiced in Europe in that it is triggered only by a severe demand and supply imbalance at major hub airports and it performs operational integration of airside and ground transportation. Mathematical programming is presented to help airlines make decisions about if and how to delay, canceling flights, or substituting flights with buses. An approximation algorithm is proposed to obtain solutions, avoiding substantial computation time required to solve large-scale nonlinear integer programming. As an evaluation, experimental data are used to compare scenarios with and without tactical intermodal substitution.