Examining the determinants of travel time use and the transfer of activities into trips

Travel time use has long been hypothesised to affect behavioural aspects of travel demand, such as mode choice and the value of travel time. However, travel time use can also influence how people organise their daily schedules because travellers can perform activities that release time outside the journey, a behaviour we call “activity transfer” in this study. This research develops a comprehensive conceptual framework to investigate the determinants of travel time use and activity transfer. For that, we utilise a rich dataset of a representative sample (n = 1673) of the Greater Melbourne and Geelong population (Australia) and implement an Integrated Choice Latent Variable (ICLV) model. We model three mutually exclusive behaviours: (1) no engagement in travel time use; (2) travel time use without activity transfer; and (3) travel time use with activity transfer, during a trip towards the individuals’ main activity (e.g., work, study, or other main trip purpose). The ICLV results indicate activity transfer as a time-management strategy for people overlapping different roles and, thus, potentially having more time constraints. Conversely, travel time use without transfer seems to be a strategy for decreasing the dislike of travelling. Activity transfer is more likely to occur in passengerised modes (i.e., public transport and car passenger) with favourable travel conditions (e.g., seat availability) and less likely to occur on short journeys. Bringing laptops with an internet connection to the trip is associated with travel time use with and without activity transfer, while smartphones are predictors only of the latter. Importantly, after controlling for other time-use-related latent constructs, polychronicity becomes a weak predictor of travel time use and activity transfer, suggesting a potential omitted variable bias in previous research. By unveiling fundamental aspects of travel time use, our results have significant implications for transport practice, including public transport investments, long-distance travel modes, and passenger vehicle automation.