Traffic calming implementation around Calgary elementary schools: Stepped wedge RCT

Author(s): HubkaRao, Churchill, Cloutier, Nettel-Aguirre, Hagel

Slidedeck Presentation:

1B HubkaRao



Collisions with motor-vehicles are a leading cause of child bicyclist and pedestrian injuries in Canada. In Alberta, over 300 children are admitted to hospital due to severe pedestrian or bicyclist injury every year. Injury rates and severity are associated with vehicle speeds and volume, but may be moderated through traffic calming. Bicycling and walking can provide significant health benefits to children; however, concerns regarding injury risk reduce participation. Since a third of child pedestrian and bicyclist injuries occur within 300 m of schools, it is important to ensure vehicles at these locations travel in a safe manner.


To compare the effectiveness of traffic calming measures (i.e., in-street signs, traffic calming curbs, and speed bumps) to decrease each traffic speed and volume, and increase active transportation prevalence, around Calgary elementary schools.


Using a stepped-wedge cluster randomized controlled trial design, eligible elementary schools will be separated into two groups: those with intersections within 100 m of the front of the school, and those without. Within each group, schools will be randomly assigned the intervention to be located either at the closest intersection, mid-block crossing, or in front of the school entrance. All schools will then be scheduled for intervention implementation, ensuring an equal number of schools per intervention and intersection-status are scheduled for implementation each week throughout the study period. Traffic measures and active transportation counts will be collected over three mid-week days during the week prior to installation of traffic calming intervention at each school, and again for three mid-week days during the week immediately following installation. The change between pre- and post-intervention for each traffic speed and volume, along with active transportation prevalence, will be compared within and between schools for each intersection-status, and intervention type. Post-intervention data will also be compared with pre-intervention data from groups yet to receive the intervention. Analyses will include generalized mixed effects model approaches.


Data collection will commence Spring, 2020. Reductions in vehicle speed are expected, regardless of traffic calming feature. Smaller reductions in traffic volume and increases in active transportation are also expected across all traffic calming features. Greater impacts on traffic speed and volume, and active transportation prevalence, are expected for speed bumps and traffic calming curbs, reflecting actual built environment change.


This study will allow us to evaluate the effectiveness of specific traffic calming measures on each reducing traffic speed and volume, and increasing active transportation prevalence around elementary schools. Municipalities may use the results of this study to prioritize installation of effective traffic calming features around other elementary schools in their jurisdictions, and inform further study of the impact of these features in non-school environments.


Reductions in traffic speed and volume and increases in active transportation around elementary schools are expected through implementation of traffic calming interventions. This study is conducted as a partnership between the City of Calgary and the University of Calgary.