The effect of lowering residential speed limits to 30 km/h on pedestrian injuries in Toronto, Canada

Author(s): Fridman, Ling, Rothman, Cloutier, Hagel, Howard
Student Paper Competition: Honourable Mention

Slidedeck Presentation Only:



Background/Context: Lower speed roads are correlated with less pedestrian injury severity. Pedestrians are 8 times more likely to die after being struck by a motor vehicle going 50 km/h compared with 30 km/h. Few studies have examined the effect of speed limit reductions on vulnerable road users such as bicyclists or pedestrians. Given the recent increase in the number of pedestrian motor vehicle collisions (PMVC) in Toronto, it is important to describe the effectiveness of interventions such as speed limit reductions.

Aims/Objectives: To examine the effect of lowering residential speed limits to 30 km/h on police reported PMVCs in Toronto, Canada between 2013 and 2017.

Methods/Targets: Using a quasi-experimental pre-post design, we investigated the influence of implementing a 30 km/h speed limit on 300 km of residential streets in Toronto that took place in between January 2015 and December 2016. Locations of streets with speed limit reductions and dates of implementation were obtained from the City of Toronto. All reported collisions involving PMVCs were provided from the Toronto Police Service from 2010 to 2017. We calculated the number of pedestrian collisions per km per month along these streets before and after the speed limit change intervention. To evaluate the safety effects of speed limit reductions, future analyses will involve modelling pedestrian collision rates per km-month using generalized estimating equation. We will model the predictor variable as a dichotomous pre-post variable and include season of collision as a covariate. We will use stratified models to further examine safety effects of speed limit reductions by age, injury severity, traffic controls, location, light, weather and road surface conditions.

Results/Activities: Between 2013 and 2017, 260 PMVCs occurred on 164 roadways (total speed limit reduced roadways n = 844) that were treated with the intervention. The majority of pedestrians involved in these collisions were between the ages of 16 and 59 years (n=161, 62%) and most pedestrians sustained minimal/minor injuries (n=217, 83%). The majority of collisions occurred in an intersection (n=215, 83%), in areas where no traffic control device was present (n=117, 45%), and in clear (n=215, 83%) and dry (n=193, 74%) conditions. The crude collision rate per 100,000 km-month decreased in the post speed limit reduction period from 2.07 to 0.97.

Discussion/Deliverables: Descriptive results demonstrated that the majority of PMVCs resulted in minimal/minor injuries and were sustained by adults, in areas with no traffic control device and on clear and dry days. Preliminary results suggest that there was a reduction in PMVC rates on roads that have had their speed limits decreased from 40 km/h to 30 km/h; however, further analyses need to be conducted to determine the significance of this reduction over time.

Conclusions: As part of Toronto's Road Safety Plan towards zero death and severe injury from road traffic incidences, the city has put an emphasis on pedestrian safety including speed limit reductions. It is important to outline the effectiveness of speed limit reductions in protecting vulnerable road users such as pedestrians.