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Table 2 Existing built environmental measures

From: GIS measured environmental correlates of active school transport: A systematic review of 14 studies

Environmental measures Definition/formula/GIS methods Scale of measuring the variables  
Distance    
Distance to school Shortest path to school along the circulation system (including roads, trails, and pathways) estimated by GIS/ArcView 3.x extension, Network Analyst V1.0b estimated the distance based on the shortest route possible along road network -- [17, 23, 27, 28]
  Straight-line distance between home and schools -- [21, 25, 26]
  Manhattan distance between school and home -- [18]
  Not reported   [29]
Distance to Central Business District Distance between the Toronto Central Business District and Traffic Analysis Zone of a respondent's home -- [25]
Density    
Residential/dwelling density The ratio of residential units to the residential area Block group/Traffic Analysis Zone [16, 18, 23]
  Total number of residents per land area Block group [20, 26]
  The ratio of total number of residents to the residential area (and commercial use) Block group [23, 29]***
Residential index Residential units as a percent of dwelling units and total employment in the traffic analysis zone Traffic Analysis Zone [18]
Employment density Number of employees per land area Traffic Analysis Zone [18]
  Employment to population ratio Traffic Analysis Zone [24]
  Ratio of sales/service employment to the population Traffic Analysis Zone [25]
  Ratio of manufacturing/trade/office/professional employment to the population Traffic Analysis Zone [25]
  Number of employees per area of industrial and commercial land Unknown [29]
Building density Area of floor space/buildings per land area Study area [27, 29]
School density Number of school per land area Traffic analysis zone [24]
Density of school- or work-related trips Walking density-total work and school related walking trips produced by residents in study area Traffic Analysis Zone [25]
Vehicle density Number of cars and motorcycles per area of roads Study area [29]
Diversity    
Mixed land use Land Use Entropy Block group/Traffic Analysis Zone [16, 18, 23, 29]***
  Herfindahl-Hirschman index-proportion of each land use squared and summed Not reported [27]
Land use intensity for commercial properties Commercial floor area ratio (FAR) = commercial floor area/commercial land area Not reported [19]
Retail floor area ratio Retail building square footage/retail square footage Block group [16]
Design-connectivity-intersections   
Intersection density The ratio of number of intersections 3- to 4-way or 3- to 5-way or not specified) to the land area/street length Block group/study area [1618, 20, 23, 27]
  Number of major road intersection (3 or 4-way) per land area (primary highway, secondary highway and major/arterial roads) Study area [25]
  Number of 4-way local street intersections Study area [25]
  Intersection number along the route to school Study area [29]
Percent of 1,3,4, and 5-way intersections Percent of 1,3,4, and 5-way intersections with the buffer Study area [18]
Connected node ratio The ratio of number of intersections to number of intersections and cul-de-sacs Study area [27]
Cul-de-sac density The ratio of number of cul-de-sac to land area Not reported [17]
Design-connectivity-route directness   
Pedestrian route directness The ratio of the distance to school along the road network to the straight-line distance -- [17, 27, 28]
Design-connectivity-streets   
Block/road density Road length (local streets, arterials, and collectors) or number of blocks per land area Study area [19]*** [25, 27, 29]***
Average block size Not reported Study area [18, 29]
Length of each types of road or all streets Total length of motorway, main street, and side street (Switzerland) in each study area Study area [26]
Proportion of primary road Length of primary roads per length of all roads   [27]
Vehicle lane width Average width of vehicle lanes along the route to school Study area [29]
Design-sidewalk and bike lanes   
Sidewalk/walking tracks length Total length of sidewalk/walking tracks in the study area Study area [23]
Average sidewalk width Not reported Not reported [19]
  Average sidewalk width along the route to school Study area [29]
Sidewalk density Proportion of street miles with sidewalk/pavement Study area [19]*** [27]
  Percentage length of sidewalks with widths wider than two metres along the route to school Study area [29]
Bike lane density Proportion of street miles with bike lanes or paved shoulders Not reported [19]
Street spatial design   
Across a motorway, main street or a side street/across busy road (freeway, highway, arterial, subarterial, collector, and local road)/across major roads, or rail roads Whether the route to school cross these road Along the estimated route to school/the straight line between school and home [17, 26, 28]
Route along busy/main or secondary road Whether the route to school along a busy/main or secondary road Along the estimated route to school [27, 28]
Route along    
Road outside child's home A major or minor road adjacent to the child's home -- [27]
Proportion of primary roads Presence of primary road as part of the route Along the estimated route to school [27]
Walkability index    
Neighbourhood walkability index Walkability=[(z net residential density) = (z retail floor area ratio) + (2 × z intersection density) + (z land use mix)] Cluster of block groups [16]
Individual walkability index Walkability=[(z net residential density) = (z retail floor area ratio) + (2 × z intersection density) + (z land use mix)] Study area [16]
Effective walkable area Total neighbourhood area (area that can be reached via the street network within 800 m from the home) divided by the potential walkable area (the area generated using a circular buffer with a radius of 800 m from the home) Study area [27]
Topography and aesthetics   
Greenery Proportion of street miles with street trees Not reported [19]
  Total number of street trees within 5 m of each road edge Study area [23]
  Number of shade trees per the length of route to school Study area [29]
Steep incline Altitude between home and school; detail not reported Along the straight line between school and home [26]
  A TIN (triangulated irregular network) file was created from the digital elevation model (data from the State of Victoria). Surface analysis was undertaken along each route to determine the presence of a steep incline along any segment using Surface Tools, version 1.5. Along the estimate route to school [28]
  Average slope gradient within residence area of a child Not reported [29]
Geographic regions Northeast, South, Mideast, or West in the US -- [22]
Urbanisation Population density>4150 persons per square mile (ppsm) = urban; 1000-4150 ppsm = suburban; <1000 ppsm = rural Not reported [21]
  Five levels of urbanisation defined by quintiles of population density and density of the surrounding areas: urban, metro suburban, second city, town, and rural Not reported [22]
  Urban, inner-suburban, outer-suburban Traffic analysis zone [24]
  Urban or rural based on address of child's home -- [27]
Proportion of route to school within an urban area Proportion of route that passes through urban area Along the estimated route to school [27]
Safety    
Traffic accidents Number of fatal or serious road traffic accidents divided by total road length Study area [27]
Streetlight density Number of streetlights divided by total road length Study area [27]
Demographic-socio-economic status   
Area-level socioeconomic status score Based on the Australian Bureau of Statistics' Index of Relative Socio-Economic Advantage/Disadvantage Not reported [28]
Neighbourhood income Median household income Block group/Dissemination area [16, 23]* [24, 25]
Socioeconomic deprivation Population weighted scores for index of multiple deprivation Not reported [27]
Percent of residents on public assistance   Census tract [18]**
Percent of household with income below poverty level   Block group/Census tract [18]**
Percent of residents unemployed   Census tract [18]**
Demographic-education   
Educational attainment at neighbourhood level Proportion of population over age 25 years with high school diploma Block group [23]*
Demographic-housing   
Percent of residents living in owner-occupied housing   Block group/Census tract [18]**
Percent of residents living in the same house as 1995   Census tract [18]**
Percent of residents living in female headed households   Block group/Census tract [18]**
Demographic-ethnicity   
Percent of persons born abroad   Block group/Census tract [18]**
Percent of non-white residents   Block group/Census tract [18]**
Demographic-single parenthood    
Single parenthood Proportion of families headed by single parents Block group [23]*
  1. *Canadian equivalent: dissemination area
  2. **Census Tract is a geographic unit comparable to Traffic Analysis Zone which was used to measure other variables.
  3. ***Scale of measuring variables is not reported.