Evaluation of voluntary travel behaviour change: Experiences from three continents

The past 20 years has seen a rapid growth across the world in the number, range and scale of voluntary travel behaviour change (VTBC) initiatives. These so-called 'soft' measures have challenged the assumption that modal shift is only possible through 'hard' system-based measures, or through regulation. Among the most high-profile VTBC initiatives is a household-based behaviour change technique known as Individualised Travel Marketing. This dialogue marketing approach was developed by Socialdata (under the brand name IndiMark®) in response to its own research suggesting that a lack of information and motivation, and incorrect perceptions of the alternatives to the car, were significant barriers to modal shift. IndiMark has been applied in more than 100 pilot and nearly 150 large-scale projects, targeting a total of more than three million people on three continents. A key factor in this widespread take up has been the consistent use of a detailed evaluation design, employing travel behaviour surveys before and after the IndiMark intervention, using Socialdata's KONTIV® survey method. This well-established design uses a self-administered, mail-back questionnaire, coupled with motivation by post and telephone to encourage high response rates (typically between 60% and 80%) helping to provide reliable data on mobility behaviour. This paper reviews the development of the IndiMark technique and the key features of its evaluation using the KONTIV® survey method. It draws on this experience to address key challenges in the evaluation of VTBC initiatives, and to identify the common threads of an integrated approach which might strengthen the case for all soft measures.