Promoting public transport as a subscription service: Effects of a free month travel card

Newspapers, book clubs, telephone services and many other subscription services are often marketed to new customers by means of a free or substantially discounted trial period. This article evaluates this method as a means to promote commuting by public transport in a field experiment and based on a solid behavioural-theoretical framework. By measuring important antecedents and mediators, the applied approach offers important insights not only on what behavioural outcomes were produced by the intervention, but why they were produced. Copenhagen car owners received a free month travel card, either alone or together with a customised travel plan or a planning intervention. A control group receiving no intervention was also included. Attitudinal variables, car habits and travel behaviour were measured before and immediately after the intervention and again six months later. The only intervention that had an effect was the free month travel card, which led to a significant increase in commuting by public transport. As expected, the effect was mediated through a change in behavioural intentions rather than a change in perceived constraints. As expected, the effect became weaker when the promotion offer had expired, but an effect was still evident five months later. Possible reasons and implications of this are discussed. (C) 2009 Elsevier Ltd. All rights reserved.