The case for urban regeneration is consistent with a social ecological model of health, in which economic conditions, as well as physical and social environments, are seen as important influences on health and well-being. However, the evidence that initiatives of this kind have produced the outcomes claimed for them is far from conclusive. One particularly contentious type of intervention is the construction of new major roads in urban areas. Although new roads make it easier for people to travel around and can improve access to employment, education and other opportunities, motor transport also incurs substantial societal costs through injuries, pollution and other undesirable impacts. In contrast, a population shift towards walking, cycling and public transport offers a potentially winning combination of an increase in physical activity coupled with reductions in traffic congestion and use of fossil fuels, and is therefore increasingly regarded as desirable on public health, environmental and equity grounds.
This study was based around the opening of an extension to the M74 motorway in Glasgow, which is the largest city in Scotland and is characterised by extremes of affluence and deprivation. The intervention, which formed part of a wider strategic initiative to regenerate the ‘Clyde Gateway’ area, comprised a new 5-mile, six-lane section of motorway opened in 2011, along with associated changes to the urban landscape such as junctions, slip roads, and housing and retail developments. The new motorway runs through predominantly deprived neighbourhoods in south-east Glasgow, is mostly elevated above ground and is parallel to an existing railway line. Proponents claimed that the new motorway would improve conditions for pedestrians and cyclists on local streets and help to regenerate local communities, whereas objectors argued that it would encourage car use, degrade the local environment and deter local walking and cycling.
Aims of the study
To assess the individual, household and population impacts of a new five-mile section of the M74 motorway in Glasgow on travel and activity patterns, road traffic accidents and well-being; and to understand how these impacts were distributed between different socioeconomic groups.
The Traffic and Health in Glasgow study was designed to take advantage of this natural experiment to address the following primary research questions:
- What are the individual, household and population impacts of a major change in the urban built environment on travel and activity patterns, road traffic accidents and well-being?
- How are these impacts distributed between different socioeconomic groups?
We also aimed to address the following secondary research questions:
- What environmental changes have occurred in practice?
- How are the effects of the environmental changes experienced by local residents?
- How are any changes in behaviour or well-being mediated and enacted at individual and household levels?
This mixed-method controlled before-and-after study was built on the foundations of a baseline cross-sectional study previously undertaken in 2005 in three local study areas in Glasgow: the ‘M74 corridor’ intervention area (‘South’) and two matched control areas, one surrounding the existing M8 motorway (‘East’) and one with no comparable major road infrastructure (‘North’). Within each area, graded measures of the proximity of the motorway to each participant’s home served as a further basis for controlled comparisons. We used a combination of quantitative and qualitative methods to evaluate changes in health and health-related behaviour, and to investigate how these changes were experienced and brought about. The study comprised six main elements:
- An environmental survey to characterise the intervention.
- A core follow-up survey of local residents in 2013, to compare changes in neighbourhood perceptions, travel behaviour (using a 1-day travel record), physical activity (short International Physical Activity Questionnaire) and well-being [Short Form 8 Health Survey (SF-8) and the short version of the Warwick–Edinburgh Mental Well-Being Scale (SWEMWBS)] in the three study areas, using a combination of cohort and repeat cross-sectional analyses. A total of 1345 participants (mean age 49 years; 61% women) provided valid data at baseline and 1343 did so at follow-up. A total of 365 participants provided valid data at both time points and thereby formed a longitudinal cohort.
- A detailed quantitative substudy of 196 survey participants in 2014–15 (mean age 54 years; 55% women), using accelerometers and global positioning system receivers to quantify differences in neighbourhood-specific and overall physical activity between study areas.
- A detailed qualitative substudy involving a combination of semistructured, photovoice and walkalong interviews with 30 survey participants purposively sampled from two contrasting localities within 400 m of the new motorway, along with 12 other key informants, in 2014–15.
- Analyses of existing national population data sets to evaluate the impact of the intervention on road traffic accidents (using police STATS19 data, 1997–2014) and to elaborate the evaluation of its impact on travel behaviour (using Scottish Household Survey travel diary data, 2009–13).
- A programme of community and stakeholder engagement to help shape the final study design, elicit a wider range of accounts and develop a shared understanding and interpretation of the emerging findings.
Dr David Ogilvie – University of Cambridge
Fiona Crawford – Glasgow Centre for Population Health
Professor Rich Mitchell – MRC/CSO Social & Public Health Sciences Unit
Professor Shona Hilton – MRC/CSO Social & Public Health Sciences Unit
Professor Nanette Mutrie – then at University of Strathclyde, now at the University of Edinburgh
Dr David Humphreys – University of Oxford
Dr Shannon Sahlqvist – Deakin University
Professor Andy Jones – University of East Anglia
Unit led study in collaboration with MRC Social and Public Health Sciences Unit, Glasgow, University of East Anglia (UEA), University of Glasgow, University of Edinburgh and Glasgow Centre for Population Health.
University of Cambridge.
The baseline phase of the study was supported by a MRC Special Training Fellowship in Health of the Public Research (award number G106/1203). The follow-up phase was funded by a grant from the NIHR Public Health Research programme held by the Unit.
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