Evaluation of Soft Transport Policy Measures Based on Behavioural Theory

This paper aims at disentangling possible causal mechanisms mediating the impacts of soft transport policies. A general conceptual framework is first presented to clarify how hard and soft transport policy measures influence travel behaviour. After that several models are presented which identify psychological determinants of people´s current travel behaviour as well as their motivation to change this behaviour. Finally, the psychological determinants are related to specific intervention types that can be used to systematically trigger behaviour change. In a last section future research directions are outlined. Motorised transport is in several respects a future threat to the human environment (Gärling and Steg, 2007). Whereas the problem diagnosis is clear, finding effective means for reducing motorised transport, especially private car use, seems difficult. There is growing evidence that hard policy measures (e.g., physical changes to transport infrastructure or operations, traffic engineering, control of road space and changes in price) alone fail to deliver the needed car use reduction (e.g. Perhaps these sobering experiences are reasons for the demonstrated interest by transport planners in a range of initiatives which are widely described as soft transport policy measures (Jones and Sloman, 2006; Rose and Ampt, 2001; Taniguchi et al., 2007). Although a consistent definition of such policies has not yet been developed, a typical feature is that they try to influence individual choice by means of information and persuasion. Frequently implemented examples of soft transport policy measures include workplace travel plans, personalised travel planning, public transport marketing, and travel awareness campaigns (e.g., Gärling and Fujii, 2006). Still, many transport planners remain sceptical whether soft transport policies should be viewed as key elements of an effective and efficient car-use reduction strategy. To overcome this scepticism strong empirical evidence is needed that soft policies can cause a substantive car-use reduction effect as well as detailed insights into the mechanisms mediating this effect. The present paper starts with a brief summary of the available empirical evidence for the effectiveness of soft transport policies. The main focus of the paper is on the causal mechanisms that may mediate the impact of soft transport policies. For this purpose a general conceptual framework is first presented to clarify the role Behavioural Theory Based Evaluation 4 of hard and soft policy measures in changing travel behaviour. After that several models are presented which identify psychological determinants of people´s current travel behaviour as well as their motivation to change this behaviour. …