Analysis of mode choice for intercity travel: Application of a hybrid choice model to two distinct US corridors

With growing concerns about greenhouse gas emissions and traffic congestion, there is an emphasis on encouraging shifts to public transport, for both short and long distance travel. Major differences exist across countries in how successful these efforts are, and the United States is often used as the key example of a country with a strong resistance to shifting away from private car use. Even within the United States however, there is strong heterogeneity across regions and across different types of travellers. This paper seeks to add empirical evidence to understand the drivers of mode choice for intercity travel, using stated choice data from two major US intercity corridors: the Northeast Corridor (NEC) and the Cascade Corridor. We develop a hybrid choice model that allows for deterministic and random variations across travellers in their preferences, some of which can be linked to underlying attitudinal constructs. Our results highlight extensive heterogeneity and provide interesting insights into the drivers of behaviour, and the relationship between attitudes and actual choices. As an example, we see that for some groups, notably West Coast respondents, a stronger anti-car attitude is counter-acted by a reduced utility for non-car modes when making choices, possibly due quality of public transport provision. Similarly, for other groups, such as older and female travellers, a reduced concern for privacy, which would benefit public transport, is counter-acted by a stronger pro-car attitude. These findings highlight the complex way in which attitudes can influence choices and provide insights for targeted policy interventions. Through scenario testing, we also show how future modal split might change depending on how these patterns of heterogeneity evolve over time, noting that the way this might happen is of course unknown at present.