Feasibility of a randomised controlled trial of financial incentives to promote alternative travel modes to the car
Journal of transport & health 2023
Alternatives to the car, such as walking, cycling and public transport can integrate physical activity into everyday life. Interventions promoting alternatives to the car targeting individual behaviour have shown modest effects, and supportive environments appear important.
This mixed-method study assesses the scientific and operational feasibility of conducting a randomised controlled trial (RCT) of individual financial incentives within a supportive physical environment. We invited residents of Northstowe, Cambridgeshire, UK who had not previously claimed financial incentives to complete a baseline questionnaire assessing socio-demographic characteristics and travel behaviour. On completion, households were randomly assigned to (1) control – claimed incentives online; (2) intervention - received incentives via email; and (3) intervention plus - received greater value incentives via email. We assessed incentive use via questionnaires at three and six months. Longitudinal qualitative interviews at baseline, three months and six months elicited views of incentives and factors influencing use.
99 residents from 88 households (household response rate: 88/475 (19%)) completed the baseline questionnaire and were randomised at household level. The local authority delivered all incentives. Compared to the control group, incentive use was higher in the intervention and intervention plus groups at six months, but there was little difference between intervention and intervention plus group. Qualitative data suggests that incentives worked by prompting existing intentions, raising awareness of alternative travel modes and to a lesser degree by reducing travel cost. This resulted in some new leisure travel behaviour, but most often to subsidise existing travel. Qualitative data suggests that existing travel preferences and environmental conditions influenced incentive use.
It is feasible to deliver an RCT in collaboration with a local authority and future trials should account for recruitment challenges. Reducing the effort required to obtain incentives increased their use, but future research should investigate the surrounding enabling environmental contexts.
This study explores the feasibility of conducting a randomized controlled trial (RCT) to encourage people in Northstowe, Cambridgeshire, UK, to use alternatives to cars, such as walking, cycling, and public transport. The town was designed to promote these modes of travel, and housing developers provided financial incentives to encourage residents to use them. In this experiment, we recruited residents who had not claimed the incentives before, and divided them into three groups. The first group could claim the incentives online (which is standard practice in Northstowe), the second received them via email, thereby lowering the effort needed to access them, and the third received higher-value incentives via email. After six months, groups that received the incentive by email were more likely to use the incentives that those who had to claim online, but higher value incentives did not make a difference. Interviews revealed that incentives prompted some participants to try new travel options, but others mainly used them to support their existing travel habits. The study found that existing travel patterns and the environmental conditions had more of an influence on travel than the incentives. The study demonstrated that working with the local authority to implement an experiment is possible, but recruitment can be challenging. Additionally, making it easier to obtain incentives increased their use, and future research should focus on ensuring the environment supports walking, cycling and public transport to maximise the effect of incentives.