Traffic calming implementation around Calgary elementary schools: Modified Stepped wedge RCT

Author(s): HubkaRao, Mishra, Churchill, Cloutier, Nettel-Aguirre, Hagel
Student Paper Competition: 3rd Place

Slidedeck Presentation:

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Collisions with motor-vehicles are a leading cause of child bicyclist and pedestrian injuries in Canada. In Alberta, every year over 300 children are admitted to hospital due to severe pedestrian or bicyclist injury. Bicycling and walking can provide significant health benefits to children; however, concerns regarding injury risk can reduce participation. Injury rates and severity are associated with traffic speeds and volume but may be moderated through traffic calming. 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 determine the effect of traffic calming measures (i.e., in-street signs, traffic calming curbs) on traffic speed and volume, and active transportation prevalence, around Calgary elementary schools.


Fifty-two regular program public elementary (gr 1-6) schools with an intersection within 100 m of the main school entrance were randomly assigned to receive one of two traffic calming features (i.e., in-street signs, traffic calming curbs). Interventions were installed at eight schools a week using a modified stepped-wedge cluster randomized controlled trial design, between July and October 2020. Twenty-seven of these schools also had data collected for one week in April 2021. Collected data included traffic speed and volume data, and active transportation counts from the week before and after installation. Generalized multilevel mixed modeling was used to analyse changes in traffic speed, with either Poisson or Negative Binomial regression used to analyse traffic volume and active transportation.


Fifty-one schools had pre and post outcome measures. During school drop-off periods (20min before to 5 min after morning bell), in-street signs were associated with an average reduction of 0.8km/h in traffic speed and six vehicles for traffic volume, and an increase of one person using active transportation. Traffic calming curbs were associated with an average reduction of 1.2km/h in traffic speed, 13 vehicles, and an increase of one active transportation user. Modelling results pending.


Overall reductions in traffic speed, volume, and active transportation were observed. Small reductions in traffic speed and volume may be due to the speed limit of 30km/h at the intervention locations. Expanding this study design to roadways with higher speed limits may lead to greater reductions in speed and volume. Reductions in active transportation may be due to the decrease in temperature rather than an influence of the intervention. Follow-up data collection at a sub-sample of locations will evaluate the longer effects of the interventions on traffic speed, volume, and active transportation. This study is conducted as a partnership between the City of Calgary and the University of Calgary.


Traffic calming curbs and in-street signs may be effective traffic calming interventions, reducing traffic speed and volume while also increasing active transportation prevalence. Ongoing analysis will further detail this relationship and the influence of related variables.

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