The association of public transport accessibility and walking and risk of chronic disease

© 2013 Dr. Alison Margaret BarrThis thesis aimed to explore the relationship between public transport system accessibility, travel behaviour and health, with an emphasis on the spatial patterning of disadvantage. The central focus of the research was a cross sectional analysis of the association of public transport accessibility and walking and risk of chronic disease in 5,241 residents of 42 randomly selected collection districts clusters in Australia, adjusting for individual and environmental level covariates. This study found a modest positive association between public transport accessibility and both walking above the median minutes per week (OR = 1.28, 95%CI = 1.03, 1.60) and above the recommended 150 minutes per week (OR = 1.35, 95%CI = 1.11, 1.63) for transport or recreation adjusting for spatial clustering, sex, age, country of birth, education, occupation, employment density and population density. These findings were similar for a subgroup of the sample who reported they did no vigorous recreational physical activity, with a 28% increase in the odds of walking above the median 90 minutes per week (OR = 1.28, 95%CI = 1.02, 1.61) and a 41% increase in the odds of walking above the recommended 150 minutes per week (OR = 1.41, 95%CI = 1.16, 1.72) for transport or recreation. These findings suggest that high public transport accessibility may support walking in groups that do not engage in vigorous recreational physical activity, and who may need other strategies for regular and sustainable physical activity, such as transport related walking. Although there is still some uncertainty in what is a relatively small evidence base, these findings lend weight to the results of previous studies that found increased spatial accessibility of public transport stops is associated with increased walking. They are also consistent with research that has largely found a positive association between public transport use or commuting and walking. In contrast to the walking outcomes, this study found no association between public transport accessibility and obesity (OR = 1.05, 95%CI = 0.85, 1.30), metabolic syndrome (OR = 1.09, 95%CI = 0.91, 1.31) or diabetes/ pre-diabetes (OR = 1.11, 95%CI = 0.94, 1.30) in the full sample, as well as the subsample who undertook no vigorous recreational physical activity, adjusting for clustering, age, sex, Aboriginality, country of birth, education, household income, occupation, rurality, area level disadvantage and area level motor vehicle ownership. There was no evidence of individual covariates including age, sex and socioeconomic status moderating the association between public transport and any of the five outcomes. Similarly there was no evidence of environmental covariates including rurality, area level socio-economic status, household car ownership, population or employment density or street connectivity moderating the association between public transport and the five outcomes. In discussing the findings, this study proposed an alternative function to distance decay for measuring the increased utility of overcoming distance by walking within a walkable distance. Some of the policy implications of the findings were also discussed, including how a health based walking catchment for public transport may sponsor both health and transport system innovation. The equity implications of opening up walking catchments around public transport stops were also considered