Longitudinal Studies in Travel Behaviour Research

Mobility is an important part of daily life. With modern mobility systems, people have access to a range of transport modes allowing them to basically reach any destination they want. Although people often have multiple options to choose from, personal mobility is dominated by motorized road transport in many countries and cities, also in the Netherlands, owing to the ease of use and high level of flexibility. This popularity poses challenges for governments to keep their countries and cities accessible, attractive, safe and liveable since motorized road transport comes with several negative effects such as increased congestion, damage to the environment, negative effects on human health due to emissions, inefficient use of space and reduced liveability of cities.
This thesis consists of studies on several mechanisms behind travel behaviour change towards sustainable travel modes, based on a large-scale longitudinal travel survey; the Netherlands Mobility Panel (MPN). As this panel has been operating for several years and collects a wide range of relevant information from its respondents, it allows studying numerous aspects of travel behaviour (change). This thesis will help policy makers understand how travel behaviour changes and provide them with knowledge to promote travel behaviour change towards a more sustainable mobility system. The focus is on four topics that are imperative to achieve this goal: the effects of life events on travel behaviour, new technologies to promote a mode shift away from car (in this case, the e-bike), the links between personal health and active travel and effects of the COVID-19 pandemic on mobility.
To correctly study these topics, longitudinal data is needed, as we want to infer the direction of effects from the data rather than making assumption on this direction, with the risk of drawing wrong conclusions (e.g., we do not know whether active travel has an effect on personal health or that the effect runs from personal health to active travel). While these longitudinal data are ideally suited to study travel behaviour changes, it is crucial that the data quality is guaranteed. To address one possible cause of low data quality, the thesis includes a fifth study focused on the notion of soft-refusal, which describes the tendency of some respondents to use a strategy to lower their response burden, e.g. by claiming they did not leave their house even though they actually did.