Evaluation of the Safety Effectiveness of Ontario’s Speed Limiter Legislation for Large Trucks

Author(s): Sarah C. Plonka, Patrick A. Byrne, Tracey Ma, Erin Dessau
Dr. Charles H. Miller Award

Slidedeck Presentation:



Collisions involving large trucks are notable for their severity. On average, close to one in five fatalities on Ontario roads involves a large truck (LT). On January 1, 2009 the Province of Ontario introduced legislation mandating the use of speed-limiting technology to restrict LT speed to 105 km/h (65 mph). A literature review indicated that only one pre-existing study used crash data to assess the effectiveness of large truck speed limiters (SLs) in reducing collisions. To determine whether Ontario's speed limiter program has been effective in reducing large truck collisions on high-speed highways. We asked:

  1. What is the effect of the speed limiter program on the frequency of collisions involving LT drivers who are at-fault due to speeding?
  2. Has the legislation inadvertently increased other collision types involving LT drivers? The study utilized a pre-post observational design, comparing police-reported collision data from a three year pre-implementation period (2006-2008) to a three years post-implementation period (2010-2012). Drivers of LTs with a Gross Vehicle Weight Rating above 11,793kg comprised the study group, while drivers of all other vehicles comprised the control group. Data source: Ontario Ministry of Transportation's (MTO) Accident Database.

For Objective 1: The main study population consisted of large truck drivers who were at-fault in a collision on a 100 km/h highway during the periods of interest. The outcome measure was taken as the proportion of these drivers who were at-fault due to speeding. Poisson regression was used to confirm that a pre/post decrease in the outcome (speeding at-fault proportion) was significantly larger for LT drivers than for drivers of other vehicles.

For Objective 2:

  1. Same analysis as above, but on 80 km/h roads; to investigate compensatory speeding on lower-speed highways.
  2. LT driver struck in the rear; to investigate claims that these collisions are a consequence of SL legislation. For Objective 1: Decrease of 72.73 percent in speeding at-fault proportion on 100 km/h highways for LT drivers, significantly greater than 29.73 percent decrease cited for other drivers (p<.005).

For Objective 2:
Similar effect to what was found on 100 km/h highways, but marginal (p=.051)
Proportion change in LT drivers struck in rear: pre (10.03), post (10.47) Our analysis indicates that Ontario legislation limiting LT speed has been a success. A decrease of 72.73 percent in speeding collisions was indicated for LT drivers as compared to a decrease of 29.73 for drivers of other vehicles. In addition, there is no evidence that the legislation has contributed to an increase in LT drivers involved in other types of collisions: no increased speeding on 80 km/h roads; no increase in drivers rear-ended because they are unable to avoid other speeding vehicles. The study was limited by low collision outcomes that prevented the use of a more identical control group i.e. trucks not requiring a speed limiter. As a result, it is possible that the analysis does not fully explain the decrease in collisions indicated. The MTO continues to support road safety through the evaluation of its programs.