Crash data before and after the Ontario province’s speed limiter mandate

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Updated Jun 16, 2021

A study concluded by the Ontario Transport Ministry in 2017, released around the time the Trump administration seemed to halt work on any U.S. mandate for truckers to utilize speed-governing technology, didn’t get much play around the U.S. trucking press as a result. But after the notion of mandated speed limiters was reinvigorated with news of a Senate bill floated to require 65-mph speed settings, more than one reader asked, what does the data from Ontario show? There’s been a limiter mandate there since the year 2009 of 105 kilometers per hour (approximately 65 mph). Readers wondered whether crash data there might show effectiveness — or its opposite — of imposing speed limitations this way.

The Ontario study I mentioned at the top you can access via this link. Conclusions by its authors, who compared crash statistics over equivalent time periods prior to 2009 implementation and after, were centered in three specific areas.

1) Did the introduction of mandated speed limiters change the number of large trucks involved in crashes where speeding was an at-fault factor for the truck driver on 100-kmh roads? 
Yes — the study points to a reduction in at-fault speeding incidents, coded merely “speed too fast” in police reports, for large trucks after the mandate. Speed-limiter-mandate supporters (the Ontario Trucking Association, for instance) as well as the report’s authors to an extent emphasized the study’s finding that at-fault speeding incidents decreased at a less dramatic rate for drivers of other vehicles, perhaps for obvious reasons (officers are well aware they’re not technologically speed-limited by law, and truckers are). The decline for truckers in at-fault speeding-related accidents went from 46 incidents in the pre-mandate period to a mere 11 in the period after the mandate. Total truck-involved accident numbers declined dramatically leading into the mandate’s introduction, as I’ve written before, but that also happened to coincide with the huge 2008-’09 recession and a big drop in vehicle miles traveled of all sorts. By 2014, however, VMT estimates had mostly returned to pre-recession levels but fatalities remained lower, at least in Ontario, for the latter:

This chart reflects years 2007-’14. 2015 and 2016 truck-involved fatalities, regardless of accident fault, were roughly similar to the ’14 numbers, according to the Ontario Transport Ministry’s annual stats reports.This chart reflects years 2007-’14. 2015 and 2016 truck-involved fatalities, regardless of accident fault, were roughly similar to the ’14 numbers, according to the Ontario Transport Ministry’s annual stats reports.

2) Did the introduction of mandated speed limiters change the number of rear-end collisions with trucks by other vehicles?
The study attempted to quantify whether rear-end accidents where trucks were on the receiving end of a collision rose after mandated limiters. Basic result: Such accidents occurred at roughly the same rate pre- and post-mandate, the study found. For one type of crash, ultimately, there didn’t appear to be an unintended consequence of slowing some trucks down. There are, however, plenty other truck-car interactions that were not focused on directly.

3) Lastly, general compliance with the speed limiter restriction was analyzed in the report, with mixed results. Take a look at the full report for more.

Bottom line: Some food for thought as you consider whether to take concerns with the recent Senate bill to your reps.

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