Background Bicycling provides health benefits but can also result in injuries. Built environment features can prevent bicycling injuries in adults; however, research on children is scarce. Additional evidence about how the built environment influences child bicycling injury is needed.

Aim To assess if built environment features are associated with child bicyclist injury risk in three Canadian regions using a case-crossover design.

Methods Children (ages 5–17) injured while bicycling presenting to emergency departments in Vancouver, Calgary, or Toronto were recruited (n=345) from May 2018 - October 2021. They completed an interview on injury circumstances, location, and details about their bicycling route. In-person built environment audits were conducted at the injury site and two randomly selected control sites along the route. A mixed-effects logistic regression model will be used to assess the association between built environment features and injury.

Results Preliminary descriptive results suggest that compared with control sites, more injury sites were: off road (41% vs 29%), areas with no path (11% vs 4%), had no bicycling signs/symbols (81% vs 72%), and frequently contained gravel (21% vs 7%). Next steps will use mixed-effects modelling to estimate the associations between built environment features and child bicyclist injury.

Conclusion Preliminary results suggest some built environment features may be associated with child bicyclist injuries. Additional analyses will be completed on route types, presence of infrastructure, and grade at injury and control sites. This case-crossover study aims to inform road safety stakeholders to develop policies and interventions to increase child bicyclist safety.