Science Spotlight

Application of environmental audit tool and GIS in school walkability

From the Mendoza Group, Division of Public Health Sciences

Active school travel (AST), walking or biking to or from school, promotes physical activity in school-aged children and aids in reducing weight gain and future obesity-linked diseases. AST is highly associated with safety and walkability within one’s built environment. Children who reside in lower income communities are more likely to be injured by pedestrians, and others, compared to children who reside in higher income communities. Other challenges children face in lower income communities include high traffic volume, long distance to school, shortage of sidewalks, and shortage of safe places to walk and ride a bicycle. Therefore, it is necessary to address walkability in these areas to increase AST and physical activity while reducing health inequities ultimately. An environmental barrier of AST has been home-to-school distances. Children who live farther from school are less likely to travel by foot or bike. Based on United States data, it is recommended that children aged 5-13 years walk up to 1-2 km to school.  However, only a few studies have reported or measured the most favorable environmental attributes for AST. Thus, it is important to develop a school walkability index (WI) based on the built environment that takes into consideration land use mix and density, traffic, slope, land cover, street/sidewalk connectivity, aesthetics, and other environmental variables. Although several researchers have developed WI for adults, measures such as land use mix and density cannot be generalized for children. 

The Mendoza Group, from the Division of Public Health Sciences, Texas A&M research team in the Department of Landscape Architecture and Urban Planning, and University of Washington research team in the Department of Urban Design and Planning,   developed an audit-based school WI to measure the effects of this metric on AST before-school physical activity in low-income elementary schools in Seattle, WA. The audit-based WI was developed from items in the modified Texas Childhood Obesity Prevention Policy Evaluation (T-COPPE) Study-based pm 0.4km buffers around schools. The objective of the study was to test both the audit-based school WI and the GIS-based school WI for their roles in predicting AST and before-school moderate to vigorous physical activity (MVPA). The study is published in the Journal of Transport and Health.

The Walking School Bus Randomized Control Trial consisted of participants from lower income families who resided in the greater Seattle area (n=18 schools) and Houston (n=4 schools). The families self-reported their transport to school and 315 students (aged 8-11), attending the 22 elementary schools, objectively measured their physical activity with an accelerometer. Students who could physically walk to and from school lived within a 1-mile network buffer of school, or those who had parents that committed to dropping them off at the stop within the 1-mile walk zone were eligible for the study. A total sample of 315 students and a subsample of 224 students who lived within 1.5 km from their school, a recommended distance for commuting, were analyzed in this study. The majority of students were from households with annual incomes of less than $60,000 and were also from diverse racial/ethnic groups including 19.8% African American, 19.8% Asian, 22.6% Hispanic, 14.4% Other race/ethnicity, and 23.4% non-Hispanic white.

Trained by Dr. Chanam Lee of Texas A&M University, auditors examined each street segment (n=841) within a 0.4m buffer from 18 schools using the field audit tool. Three domains were assessed for each street segment: land uses and housing types, street characteristics, and neighborhood perceptions. All audit-based school information was digitalized in ArcGIS 13.0, and school-level variables were created to calculate the audit-based school WI. For the GIS-based school WI, a 2 km network buffer was calculated from each school. The outcome variables were self-reported AST and physical activity (objectively measured via accelerometer). The students in the study wore the accelerometer for one week; an average of MVPA for 90 minutes before school was used to measure physical activity during the commute to school. Dr. Sungmin Lee of Texas A&M University led analyses and used mixed-effects linear modeling for physical activity and mixed-effects logistic modeling for AST

Graphical Representation of  Walkability Index
Walkability Index Image from Dr. Jason Mendoza

Home-to-school distance was positively associated with children’s AST at least once a week. However, the total sample of audit-based school WI was not associated with AST. Among the subsample, the audit-based WI was significantly associated with AST after adjusting for covariates. Within the subsample, a child living within 1.5 km of the school will walk or bike to school at least once a week (OR=5.31, 95% CI=1.78-15.84).  The total sample (Coeff= 1.81, 95% CI= 0.30-3.33) and subsample (Coeff=2.20, 95% CI= 0.61-3.79) of audit-based school WI was associated with more minutes of MVPA after adjusting for covariates. The GIS school-based WI was not associated with children’s AST. However, the total sample (Coef=0.29, 95% CI=0.04-0.54) and subsample (Coef=0.40, 95% CI=0.16-0.63) of GIS school-based WI was significantly associated with children’s MVPA

This study introduced the audit-based school WI and GIS-based school WI as tools to study the impact of the built environments on children’s walking to school and physical activity near low-income elementary schools. Dr. Sungmin Lee, the first author, summarized the study, “Since emerging evidence supports a link between neighborhood environments and walking to school among school-aged children, systematic methodologies for characterizing neighborhood environments near the school are needed to promote their physical activity that can help combat childhood obesity, especially in children residing in lower income communities. Thus, we have developed new ways to measure the route-specific and place-specific school neighborhoods targeting children and school commuting.” Dr. Mendoza, the senior author, concluded that “this research helps us describe neighborhood environments that support children’s physical activity and walking to school, and provides ideas for improving our neighborhoods to support children’s health”.

This research was supported by the National Institute of Health (R01CA163146; PI: Mendoza).  

Fred Hutch/UW Cancer Consortium member Jason A. Mendoza contributed to this work.

Lee S, Lee C, Nam JW, Abbey-Lambertz M, Mendoza JA. 2020. School walkability index: Application of environmental audit tool and GIS. Journal of Transport & Health. Sep 1; 18:100880. https://doi.org/10.1016/j.jth.2020.100880