title: GIS measured environmental correlates of active school transport: a systematic review of 14 studies.
abstract: BACKGROUND
  Emerging frameworks to examine active school transportation (AST) commonly emphasize the built environment (BE) as having an influence on travel mode decisions. Objective measures of BE attributes have been recommended for advancing knowledge about the influence of the BE on school travel mode choice. An updated systematic review on the relationships between GIS-measured BE attributes and AST is required to inform future research in this area. The objectives of this review are: i) to examine and summarize the relationships between objectively measured BE features and AST in children and adolescents and ii) to critically discuss GIS methodologies used in this context.
  
  
  METHODS
  Six electronic databases, and websites were systematically searched, and reference lists were searched and screened to identify studies examining AST in students aged five to 18 and reporting GIS as an environmental measurement tool. Fourteen cross-sectional studies were identified. The analyses were classified in terms of density, diversity, and design and further differentiated by the measures used or environmental condition examined.
  
  
  RESULTS
  Only distance was consistently found to be negatively associated with AST. Consistent findings of positive or negative associations were not found for land use mix, residential density, and intersection density. Potential modifiers of any relationship between these attributes and AST included age, school travel mode, route direction (e.g., to/from school), and trip-end (home or school). Methodological limitations included inconsistencies in geocoding, selection of study sites, buffer methods and the shape of zones (Modifiable Areal Unit Problem [MAUP]), the quality of road and pedestrian infrastructure data, and school route estimation.
  
  
  CONCLUSIONS
  The inconsistent use of spatial concepts limits the ability to draw conclusions about the relationship between objectively measured environmental attributes and AST. Future research should explore standardizing buffer size, assess the quality of street network datasets and, if necessary, customize existing datasets, and explore further attributes linked to safety.
authors.affiliation: Faculty of Physical Education & Health, University of Toronto. bonnyym.wong@utoronto.ca
authors.forename: Bonny Yee-Man
authors.initials: BY
authors.lastname: Wong
authors.forename: Guy
authors.initials: G
authors.lastname: Faulkner
authors.forename: Ron
authors.initials: R
authors.lastname: Buliung
mesh_terms: D000293:Adolescent; D001642:Bicycling; D002648:Child; D015444:Exercise; D040362:Geographic Information Systems / Q000706:statistics & numerical data*; D006801:Humans; D011156:Population Density; D012111:Residence Characteristics; D012574:Schools; D012931:Social Environment; D014186:Transportation; D016138:Walking