Evaluating voluntary travel behaviour change: Suggested guidelines and case studies

Since the late 1990s, voluntary travel behaviour change (VTBC) has been an increasingly popular strategy in Australia, applied to reduce both reliance on the car and greenhouse gas emissions. Early efforts to evaluate the impact of this strategy were generally implemented by the agency that also implemented the policy and used small sample, self-report surveys. The paper starts out by discussing the nature and size of travel behaviour changes that are frequently expected in current policy, noting that these are often smaller than the sampling and measurement errors in traditional methods of measuring travel behaviour. The paper then discusses some alternative methods of evaluating voluntary travel behaviour change implementations using panels to reduce sampling error, and using a combination of personal Global Positioning System devices and odometer reading surveys to measure travel patterns. From these considerations, a number of guidelines are suggested for what is required to evaluate voluntary travel behaviour change. The paper describes three recent case studies in Australia in which such methods have been used and evaluates the methodological approaches used in these studies against the suggested guidelines.