Funded projects

We will track changes in travel behaviour, physical activity and wider health impacts in a longitudinal study, comparing commuters living in the geographical corridor served by the Cambridgeshire Guided Busway with a control group who commute to the same employment sites in Cambridge from a comparable area and are matched on their overall demographic and socioeconomic characteristics. This will involve a questionnaire survey in 2009 (before the opening of the busway), repeated in 2010 and 2011. About half of participants will also wear activity monitors (accelerometers) to provide objective data about their physical activity. We will invite some participants to opt in to enhanced follow-up studies of travel behaviour, physical activity energy expenditure and estimated carbon emissions using household travel diaries, combined heart rate and movement sensors and global positioning system (GPS) monitors. We will also interview a smaller number face-to-face, both before and after the opening of the busway, to explore their experiences of using different modes of transport and how the new transport infrastructure has influenced their behaviour.

From a public health perspective, the intervention will be judged a success if it increases walking or cycling as part of the journey to and from work, and the research will be judged a success if it increases our understanding of how and why this type of intervention is or is not effective in changing travel behaviour and in which groups of people; of the contribution of active travel to overall physical activity and how future intervention strategies could increase this contribution; and of the wider health impacts of changes in travel behaviour.

The study will be carried out in a public health research institution with particular expertise in the measurement of physical activity in collaboration with specialists in environmental sciences, transport studies and qualitative research. Postdoctoral researchers will be appointed from the various disciplines involved, as will support staff to coordinate and manage the study and the large, complex and interrelated datasets generated. The host institution has extensive expertise in large population studies and trials using the research techniques involved. The applicants have previously published widely on the individual and wider determinants of physical activity, complex intervention development and evaluation, and evidence synthesis at the transport—health interface and have previously collaborated in both academic and policy settings.

Provisional ethical approval for the baseline phase of the study has already been granted. Participants will not be exposed to any invasive or intrusive research procedures. They will opt in to the study by responding to emails, posters and other announcements and will not be selected from any existing database. They will be entered into a prize draw to win one of eight £50 gift vouchers, which we regard as an appropriate response to the well documented decline in response rates to questionnaire surveys in health research.

Neither the Department for Transport nor any local transport or health authority have any plans to evaluate this flagship infrastructure project beyond the simple monitoring of basic patronage and traffic data. The research grant requested amounts to less than 1% of the cost of the intervention (£116M) whose health impacts will be comprehensively evaluated using a unique and highly rigorous combination of methods. Our proposal offers particular value for money by building on pump-priming funding and infrastructural support for the urgent collection of baseline data from the host institution and by drawing on large existing stocks of measurement devices which would otherwise greatly increase the cost of the study.

The project will address the following primary research question:

Is investment in new high-quality transport infrastructure associated with an increase in the use of active modes of travel (walking and cycling)?

and the following secondary research questions:

• What are the wider health impacts of changes in travel behaviour in terms of overall physical activity, wellbeing, sickness absence and carbon emissions?
  
• What are the determinants of the use and uptake of active modes of travel?
  
• How are any changes in travel behaviour distributed in the population?
  
• How are any changes in travel behaviour brought about and experienced?
  
• Are changes in travel behaviour sustained over time?
  

The core of the project will be a controlled quasi-experimental cohort study with the following elements:

Population: Adult commuters

Intervention: New high-quality transport infrastructure provided in the intervention area

Comparator: No comparable improvement to transport infrastructure in the control area

Primary outcome: Change in daily active commuting time (time spent walking or cycling on the journey to and from work)

Secondary outcomes: Changes in (a) total daily active travel time, (b) overall physical activity, (c) wellbeing, (d) sickness absence, and (e) estimated carbon emissions attributable to travel.

These outcomes will be ascertained using a combination of questionnaires and activity monitoring using accelerometers completed at baseline and repeated after one and two years.

The core study will be complemented by nested in-depth studies comprising a longitudinal qualitative semi-structured interview study, a household travel diary study, and an enhanced activity monitoring study using combined heart rate and movement sensors and global positioning system (GPS) monitors.

The intervention to be examined is the 'natural experiment' of the opening of the Cambridgeshire Guided Busway, a major and innovative transport infrastructure project that will provide a dedicated high-quality off-road route for buses and cyclists between Cambridge and its hinterland.