The “Path” Not Taken: Exploring Structural Differences in Mapped- Versus Shortest-Network-Path School Travel Routes

摘要

Objectives. School route measurement often involves estimating the shortest network path. We challenged the relatively uncritical adoption of this method in school travel research and tested the route discordance hypothesis that several types of difference exist between shortest network paths and reported school routes. Methods. We constructed the mapped and shortest path through network routes for a sample of 759 children aged 9 to 13 years in grades 5 and 6 (boys?=?45%, girls?=?54%, unreported gender?=?1%), in Toronto, Ontario, Canada. We used Wilcoxon signed-rank tests to compare reported with shortest-path route measures including distance, route directness, intersection crossings, and route overlap. Measurement difference was explored by mode and location. Results. We found statistical evidence of route discordance for walkers and children who were driven and detected it more often for inner suburban cases. Evidence of route discordance varied by mode and school location. Conclusions. We found statistically significant differences for route structure and built environment variables measured along reported and geographic information systems–based shortest-path school routes. Uncertainty produced by the shortest-path approach challenges its conceptual and empirical validity in school travel research. Recent policy and research on children’s school travel has responded to reports of decadal declines in active school travel (AST)—that is, traveling to or from school under one’s own power, typically on foot or using a bicycle—in many Western nations. 1–6 Evidence of a similar trend is also beginning to emerge in some cities in the global south. 7 AST decline has been matched by increased prevalence of overweight and obesity in children and youths. 8–10 Children driven to and from school and other activities miss transport-centered opportunities for physical activity and health benefits 11–13 that, when combined with physical activity from other sources, could produce an active healthy lifestyle that may be sustained into adulthood. 14–19 Understanding how to encourage AST could progress through development of valid evidence about the relationship between school travel route characteristics and travel mode choice. School travel research has often examined the relationship between travel mode choice and home, school, and route environments. 20 Underpinning this work is the hypothesis that built environment (BE) features may enable or restrict household transport choices. A mix of BE effects, with some indication of difference by age, time of day, location (e.g., home, route, or school), and measurement approach (e.g., objective or subjective assessment), have been found. 21–23 Studies of home, school, and travel mode without route information have suggested that both objective measures and perceptions of BE features and their use (i.e., traffic on busy roads) predict AST. 21,23–25 Reported effects are not always in the same direction across studies. The odds of walking have been shown to increase with residential density in some studies but not in others. 21,23,24 Marked differences in BE effects have also been reported when separate models are estimated for the morning and afternoon school travel periods. 21 For example, and unique to their school-to-home model, Larsen et al. 21 found that the effect of mixed land use (AST is more likely with mixed land use) intensified for the trip home; residential density became significant, along with income (i.e., AST is more likely in lower income neighborhoods); and a street tree effect (i.e., trees provide shade and are a direct and indirect measure of neighborhood aesthetics), significant in the morning model, was not reproduced. Route-based studies extend the home, school, and travel mode work by including BE features that children might experience along their route that could influence a household’s school travel decisions. For example, a child’s possible interaction with busy roads while walking to or from school could underlie a parent’s decision to drive. Route-based studies have typically involved measuring BE characteristics along and around assumed routes modeled using a geographic information systems (GIS)–based shortest-network-path algorithm. 26–32 Although several diverse route effects have been reported, all studies have reproduced the finding that children are less likely to walk as route distance increases. 26–32 Here again, different effects are reported for to- and from-school trips. 26,27 For example, Larsen et al. 26 reported significant effects for the presence of street trees, detached housing, and land use mix, that did not materialize in their school-to-home model. Findings regarding route directness, typically measured as the deviation of an assumed GIS-estimated route from the straight-line distance between home and school, have also been inconsistent. For adults, route directness is often associated with the use of active modes. In the sch