Installation of speed humps and pedestrian-motor vehicle collisions in Toronto, Canada: a quasi-experimental study

BACKGROUND Evidence related to the effectiveness of speed humps on reducing pedestrian-motor vehicle collisions (PMVC) has been conflicting. The purpose of this study was to determine the association between speed hump installation and changes in PMVC rates in Toronto, Canada. METHODS Speed humps were mapped along with police-reported pedestrian collisions from 2000-2011 and built environment roadway characteristics. A quasi-experimental study identified collision counts before and after speed hump installation, modeled using repeated measures Poisson regression adjusted for season and roadway characteristics. Stratified analyses were conducted by age group and injury severity. RESULTS There were 27,827 PMVC, with 1344 collisions along 409 roadways with speed humps. PMVC incidence rates/meters of road/month decreased after installation of speed humps (IRR 0.78 95 % CI 0.66, 0.91). Winter, collector roads (versus local), pre-amalgamated city centre and increased land use mix were associated with more collisions. The association between speed humps and PMVC rates decreased more for children (IRR 0.57, 95 % CI 0.41, 0.79) than for adults (IRR 0.80, 95 % CI 0.68, 0.95). CONCLUSIONS Speed humps are an easily replicated method of traffic calming which have a significant protective effect on PMVC on the roadways where they are installed, particularly for children. There is a need for an area-wide analysis to determine the effects of the installation of speed humps to ensure that PMVC are not being displaced to surrounding roadways.