Encouraging sustainable commuting behaviour through smart policy provision: a stated preference mode-choice experiment in the Greater Dublin Area

This paper explores the results of a stated preference (SP) experiment used to test the impact of policy incentives on commuting modal choice in the Greater Dublin Area (GDA). As a method of encouraging 'car-shedding' behaviour, various policy tools that improve the time, cost and convenience trip attributes of carpooling and car-sharing are examined. These measures are assessed in the literature as an empirical strategy of influencing a shift from single occupancy vehicle (SOV) use to more sustainable usage of the private car, such as carpooling and car-sharing. The SP experiment acts as an effective policy appraisal tool by analysing the behavioural responses to hypothetical choice scenarios and identifying the impact of policy incentives on modal share and choice probabilities. As a result of the analysis presented in this paper, an indication of the potential levels of 'car-shedding' in the GDA is determined. The discrete choice multinomial logit (MNL) findings suggested that a reduction in the modal share of SOVs of up to 8% could be realised given the policy implementation recommended. In addition to this, a 1% change in the time, cost and convenience attributes dictated an increase of up to 0.34% in the probability of carpooling and car-sharing being chosen. This paper provides weight to the argument that additional funding assigned to policy incentives alone is an effective strategy in reducing the number of commuters driving alone to work or education.