Background Alternatives to the car, such as walking, cycling and public transport may be one way to integrate activity into everyday life. Interventions promoting alternatives to the car targeting individual behaviour have shown modest effects; and supportive environments appear important. However, the intersection between behavioural and environmental interventions remains unexplored. Healthy New Towns were funded in 2015 in England and built on principles intended to create environments which favour alternatives to the car. The study assesses the scientific and operational feasibility of conducting a randomised controlled trial (RCT) of individual behavioural incentives in Northstowe, a Healthy New Town in Cambridgeshire.

Methods New residents who had not yet claimed an incentives package (voucher for walking and cycling equipment; bus travel; electric bike hire; and a bicycle maintenance session) were invited to complete a brief baseline survey assessing socio-demographic characteristics and travel behaviour. On completion, households were randomly assigned to (1) control – claim incentives online as usual; (2) intervention – receive incentives via email, reducing the action required by individuals; and (3) intervention plus – receive greater value incentives via email. Repeat surveys at 3 and 6 months also assessed incentive use. Longitudinal qualitative interviews elicited views of incentives and factors influencing uptake. Operational feasibility was assessed as e.g. recruitment, retention and uptake; scientific feasibility as the potential of the interventions to change travel patterns.

Results Of households (n=475) invited to participate, 99 residents from 87 households (response rate: 21%) completed the baseline survey and were randomised. At baseline, 13% of households did not own a car; 44% of participants travelled to work by car frequently. The local authority successfully delivered all incentives. However, existing structures for delivering incentives (such as availability of dates for maintenance sessions and use of group-based voucher codes) meant no individual usage data were available for analysis and some participants struggled to access incentives. For those who were able to access incentives, uptake was influenced by existing travel preferences and used to supplement existing behaviour. Incentives were rarely used to initiate new behaviours, and some environmental barriers such as unfinished surfaces remained.

Conclusion This study demonstrated that it is pragmatically feasible to work in partnership with local authority staff to deliver a RCT. However, the scientific feasibility of implementing incentives to change behaviour was questionable due to challenges with access to, and relevance of, incentives, and a less supportive environmental context for active travel than expected.