Determining people’s ease and difficulty of movement based on observed travel behavior

Abstract

This paper presents an approach to use GPS-based travel behavior surveys to determine who is being served well and who is being served poorly by the transport system. We draw on the extensive literature on travel behavior, which has shown that people’s travel behavior is at least in part shaped by the travel barriers they experience. Starting from this basic insight, we define 17 parameters that may provide insight into a person’s relative ease of movement. These ease of movement parameters cover dimensions related to trip frequency and diversity (e.g., overall and in evening hours), transport mode use (e.g., as driver or passenger), travel speed (e.g., for public transport legs), distance (e.g., trip detour ratio), and effort (e.g., ratio between trip legs and out-of-home activities). No single parameter is sufficient to determine whether someone is served well or poorly by the transport system, as behaviors may be the result of choice as well as constraint. However, we argue that jointly the parameters are likely to differentiate well-served from poorly-served people. We apply our approach to data from six GPS-based travel behavior surveys conducted in Israel’s four main metropolitan areas (N = 62,981). We calculate z-scores for all ease of movement parameters, with negative values suggesting mobility problems and positive values relative ease of movement compared to the entire sample. We conduct four known-group analyses, comparing mean z-scores by level of access to a private motorized vehicle, age, gender, and disability. Results are systematically in line with expectations: population segments identified in the literature as experiencing (more severe levels of) transport disadvantage show systematically lower composite mobility scores. These outcomes are particularly striking, considering the short observation period of only one day per respondent. Taken together, these findings provide a first indication that revealed travel behavior patterns can be used to identify population segments poorly served by the transport system and thus to determine both success and failure of the existing transport system. While more research is needed, the approach also holds promise to determine the impacts of transport projects on people’s ease of movement.