Transport, Physical Activity and Health: Researching the Effects of a New Urban Motorway in Glasgow
David Ogilvie, Mark Petticrew , Medical Research Council, UK; Richard Mitchell, Stephen Platt , University of Edinburgh, UK; Nanette Mutrie, University of Strathclyde, UK
We lack good evidence of how new transport infrastructure affects active travel, physical activity and health. We will outline the methodology of a novel intervention study and the results of cross-sectional analysis of our household survey data.
In recent years, the existing motorway network in Glasgow has become increasingly congested. Local and national government recently announced a decision to build a new 8 km section of motorway through a predominantly urban area at an estimated cost of £500 million (about ?700 million). This is intended to relieve congestion, reduce accidents, promote economic regeneration, and improve conditions for pedestrians and cyclists on local streets. However, it is also predicted to have significant adverse environmental effects in some neighbourhoods, and its compatibility with overall sustainability objectives has been questioned. It is the most expensive transport project in Scotland, and has attracted increasing controversy since the government overruled the findings of a public inquiry which recommended against construction.
Major transport projects of this kind may influence population health in various ways, and health-related claims are now often implicit in the case for such projects. In Glasgow, for example, explicit claims that the new motorway will improve conditions for pedestrians and cyclists on local streets, and quality of life for local residents, imply that local people are expected both to walk and cycle more and to feel better as a result of the new motorway. However, the evidence available to support such arguments is questionable.
Most research on transport and health has focused on road safety or pollution, but other questions are now attracting the attention of public health researchers. In particular, it is now a priority of health policy throughout Europe to reverse the decline in levels of physical activity in the population. This has led to increasing interest in understanding and acting on environmental determinants of physical activity. There is growing evidence of an association between certain characteristics of the local environment (encapsulated in the concept of ?walkability?) and levels of physical activity. However, as we showed in a systematic review of research findings presented at ETC 2004, we lack good evidence about the effects of changing transport policy or infrastructure, or about how the benefits and harms of such interventions are distributed in the population.
We have therefore designed a study to assess the actual effects of the new M74 motorway on these particular aspects of health. The aims of this paper are (1) to outline the methodological issues encountered in attempting to reach a feasible study design, and (2) to present the results of cross-sectional analysis of one component of the study, a local household survey.
Like most major transport projects, the M74 project is unique to its context and cannot easily be separated from the other components of the transport, land use and economic policies within which it occurs. We had to plan the baseline data collection required for a longitudinal study before we could be certain that construction would take place. There was no simple way of defining a population or area that was to be exposed to the intervention or of defining control (comparison) groups or areas. Projections based on previous studies suggested that changes in quantitative measures of health-related behaviour would be subtle and difficult to detect.
We have framed the baseline study as a cross-sectional study in its own right, exploring the relationships between travel behaviour, perceptions of the urban environment, physical activity, general health and wellbeing, and socio-economic position. We will then use these cross-sectional findings to develop and refine more precise longitudinal hypotheses to be tested after the motorway is opened.
We have adopted a mixed-method design combining quantitative and qualitative methods:
- A regional area study, using data from the Scottish Household Survey to examine changes in the socio-spatial patterning of travel behaviour across the region
- A local area study, consisting of repeated postal questionnaire surveys to households close to the route of the new motorway and in two control (comparison) areas elsewhere in the city. The questionnaire includes a travel diary, standard instruments to assess general health and physical activity, and specially-constructed items to assess perceptions of environmental characteristics
- A micro area study, consisting of qualitative interviews with residents of specific neighbourhoods predicted by the environmental impact assessment to experience particular positive or negative effects.
We will present results of the analysis of the cross-sectional (baseline) phase of the local area study, which is a survey of a random sample of adults (total n=1300) living in three specially-defined areas of the city with similar overall socio-economic profiles: one area close to the route of the new motorway, one area close to the existing urban motorway network, and one area away from existing motorways.
We will summarise the results of the following analyses currently in progress:
- Do people who live close to an urban motorway report less favourable perceptions of their local environment and/or poorer health and wellbeing?
- To what extent is mode choice, particularly time spent in active travel, associated with personal factors (e.g. age, sex, health), household factors (e.g. economic status, access to a car), spatial factors (e.g. proximity to a motorway), and perceptions of the local environment?
- Are people who report more active travel more likely to report more physical activity in general and/or better health and wellbeing?
- What contribution does active travel make to people?s overall levels of physical activity, and what is the potential for increasing that contribution by shifting mode for short journeys?
We will discuss:
- The importance and difficulty of developing studies capable of addressing research questions that straddle the interface between transport and health
- The implications of our findings for the health-related claims made for and against the construction of the motorway
- How the cross-sectional findings will be used to refine the design of the longitudinal study.
Association for European Transport