Health impacts of the M74 urban motorway extension: a mixed-method natural experimental study

Background: Making travel easier can improve people’s access to opportunities, but motor transport also incurs substantial undesirable health and social impacts. Aims: To assess how a new urban motorway affected travel and activity patterns, road accidents and well-being in local communities, and how these impacts were experienced and brought about. Design: The Traffic and Health in Glasgow study, a mixed-method controlled before-and-after study. Setting: Glasgow, UK. Participants: Repeat cross-sectional survey samples of 1345 and 1343 adults, recruited in 2005 and 2013, respectively. Of these, 365 formed a longitudinal cohort, 196 took part in a quantitative substudy using accelerometers and global positioning system receivers and 30, living within 400 m of the new motorway, took part in a qualitative substudy along with 12 other informants. Complementary analyses used police STATS19 road traffic accident data (1997–2014) and Scottish Household Survey travel diaries (2009–13). Intervention: A new 5-mile, six-lane section of the M74 motorway, opened in 2011 and running through predominantly deprived neighbourhoods in south-east Glasgow, with associated changes to the urban landscape. Main outcome measures: Differences in self-reported travel behaviour (1-day travel record), physical activity (short International Physical Activity Questionnaire) and well-being [Short Form 8 Health Survey (SF-8) and a short version of the Warwick–Edinburgh Mental Well-being Scale], and in the incidence of road traffic accidents.