Sperimentazione e modellizzazione di un programma di cambiamento volontario del comportamento di viaggio

This research is motivated by the need to gain a better understanding of individual behaviour change processes and in particular assess the efficacy of travel behaviour change strategies. This work aims to provide major insights into how to reduce private car use and addresses sustainable mobility objectives associated with CO2 reduction. This is particularly important at a time when the car still dominates individual lifestyles. In this regard, it has been demonstrated that, though many people are willing to reduce personal car use, in practice, they are unable to do so on their own (Ampt, 2003). Thus, strategies and measures have emerged to encourage and inform people to consciously and deliberately rethink their travel choices. These are called soft measures (Bamberg et al., 2011), and are also labelled Voluntary Behavioural Change Programmes (VTBC) (Ampt, 2003). The Voluntary Travel Behaviour Change (VTBC) programmes are policy interventions that provide appropriate information, assistance, and motivation (or incentives) for promoting more sustainable travel behaviour, inducing people to voluntarily choose to travel in ways that benefit themselves, the community, and the environment. Through the provision of information and motivation to switch to more sustainable modes of travel, VTBC programmes aim to reduce the motorized vehicle-kilometres travelled (VKT) thereby reducing greenhouse gas (GHG) emissions and energy consumption. In a context characterized by the reduced availability of financial resources for new investments in infrastructure (supply side), VTBC programmes can offer a useful tool for managing (and reduce) travel demand. Results from several VTBC implementations have shown the effectiveness of these policies in reducing private car use. However, there is a dearth of research on identifying and quantifying the influence of individual factors on the propensity to change travel behaviour. The effectiveness of a programme should be assessed in relation to the target population and the type of information provided. Indeed, identifying relatively micro-level factors underlying behavioural change could enhance the effectiveness of the programme, in terms of the selection of specific individual segments (who may be more sensitive to certain aspects of the programme), and in terms of the type of information provided and emphasis placed on the personalized travel plan (monetary benefits, reduction in travel time, decrease in CO2 emissions, etc.). The objective of this thesis work is to contribute to the development of a programme for voluntary travel behaviour change, adopting an innovative approach consisting in: (1) the analysis of models of behaviour and theories of change (Chapter 1); the two bodies of theory are considered indeed complementary; understanding both is necessary for developing effective approaches to behaviour change. (2) a review of existing VTBC programmes implemented in different parts of the world, in order to identify the main steps to be followed for changing travel behaviour (Chapter 2), (3) the development and application of a method (Chapter 3) aimed at testing and validating innovative tools applied in the first Italian VTBC programme; (4) verifying the efficacy of the method through an in-depth analysis of activity travel data collected before and after the implementation of the policy measure (Chapter 4); (5) the formulation of models aimed at gaining a deeper knowledge of behaviour change and in particular that are able to simulate the effects of implementing these measures and their efficacy in changing travel behaviour (Chapter 5). For this purpose, an experimental VTBC programme was conducted in Cagliari (Italy) between 2011 and 2012 to promote the use of a underutilized light rail service among car users travelling daily along the same congested corridor. The programme was funded by the Autonomous Region of Sardinia. The methodological approach relies on the personalized travel planning technique (PTP), integrating traditional and innovative tools, aimed at enhancing the efficacy of a VTBC programme. In particular, compared to the existing programmes, in this work the method developed relies on innovative tools for (1) selection of participants, (2) promoting and, (3) monitoring behaviour change. The data collected during the implementation are examined by means of exploratory and discrete choice analyses. The results obtained revealed that the selection process undeniably enabled to intercept individuals interested in the alternative mode promoted. An efficient selection and the PTP itself, certainly complement each other, in the sense that selecting the target audience was a necessary condition for promoting a convenient alternative, whereas providing car users with detailed feedback about their current behaviour and existing alternatives seems to have positive effects on behaviour change. It appears that information about the major benefits to be gained from changing travel behaviour are more likely to encourage the switch to alternative modes. People will choose to change of their own free will if the benefits are very substantial. Another finding that emerged from the short term monitoring phase (three months after programme implementation) is that once car users, selected among those with an available sustainable alternative, experience the benefits of switching to an alternative mode (of their own free will or following a suggestion), they rarely revert to using their cars. The model simulation revealed that the effectiveness of VTBC programmes in producing a shift toward sustainable modes is a function of the demographic, attitudinal, and activity-travel context of individuals. Disregarding these moderating effects can lead to incorrect predictions of the aggregate shift toward the sustainable mode as well as of the distribution of the shift across population segments. Further, accommodating the contextual variations can also help in targeting and positioning VTBC programmes, and in tailoring different aspects of the programme to individuals’needs so as to enhance its effectiveness.