The integration of air and rail travel has been increasingly adopted by major European airlines such as Air France-KLM and Lufthansa, as part of their efforts to reduce short-haul flights within Europe. This in order to improve local air quality, reduce greenhouse gas emissions, and contribute to the European Commission's goal of achieving Net Zero emissions by 2050. While much of the existing literature has focused on the substitution of short-haul flights with high-speed rail for direct origin-destination travel, this study explores the integration of air and rail transport in multi-legged journeys. Specifically, it examines the incorporation of high-speed rail as spokes in the hub-and-spoke model used by major airlines.

This study aims to quantify the preferences of potential air/rail travellers in order to provide airlines, airports, and other stakeholders with insights into the key features such as service, comfort and operational factors of an integrated air/rail service. A stated preference survey, distributed among the Dutch Railways (NS) panel, was used to collect data, with a total of 541 respondents. The data is analysed using linear regression analyses and a multinomial logit model to estimate coefficients for the included parameters. Additionally, a latent class choice model was used to capture heterogeneity among the respondents in order to identify several consumer segments.

This study found that integrated ticketing was the most attractive service attribute, while priority lanes provided the highest comfort. Travel cost emerged as the most crucial determinant for choosing air/rail over air/air journeys, followed closely by the spend at the airport and train station in an air/rail journey. The latent class choice model revealed that younger, less experienced travellers were most likely to switch from air/air to air/rail, particularly in scenarios involving high levels of service and comfort integration.

This latent class choice model identified three customer groups: waiting time disfavourites (young, less experienced travellers), plane lovers (middle-aged, experienced travellers), and air/rail service admirers (mostly elderly, retired). Waiting time disfavourites, who prioritize minimizing waiting time at airports and stations, choose air/rail in 53.0% of cases. Plane lovers strongly prefer air/air, with 85.1% favouring it. Air/rail service admirers, valuing service highly, choose air/rail in 97.9% of cases.

According to a real-life scenario analysis about the introduction of an air/rail terminal at Frankfurt Airport, the current offered services and comfort features increases the share of air/rail from 31.4% (102 passengers) to 45.7% (148 passengers), which equals a substitution rate of 14.3%. With further integration, the air/rail share could be increased to 76.4% (249 passengers) among the first group of young, less experienced, travellers. However, the impact on plane lovers is minimal, with a maximum substitution rate of 19.7%. The third group already favours air/rail over air/air, so a maximum substitution rate of 2.7% can be achieved. However, overall, a maximum air/rail share of 67.7% can be reached, equal to 173 additional passengers choosing for air/rail.