Drs. John Carsley and Kay Teschke: Turns out — duh! — that increasing speed limits didn’t increase highway safety

In 2014, after a strange consultation process, former transportation and infrastructure minister Todd Stone approved increased speed limits on many rural highways in B.C. Recently, the third independent study to document significant increases in deaths and serious injuries on these routes was published. Ironically, the reason originally given for increased speed limits was increased safety. How did this come to pass and what should we do about this unfortunate outcome?

The rationale that speed-limit increases make roads safer depends on the very shaky idea that the difference between fastest and slowest vehicles travelling in the same direction decreases when the speed limit is raised. It’s hard for most folks to imagine.

Since the increases in B.C., speed differentials on those routes remained the same or increased. Faster vehicle speeds increases the risk of serious injury and death in a crash. Higher speeds allow less margin for controlling a vehicle, reacting, avoiding and stopping.

Worldwide, speed limits, whether on city streets or rural roads, are being decreased to save lives. The most recent example is France, which announced this month that speed limits on undivided two-lane roads will be reduced to 80 km/h from 90 km/h for safety reasons.

It is not clear why Stone decided that our speed limits needed adjustment. That S.E.N.S.E — Safety by Education, Not Speed Enforcement — a tiny pro-speed, anti-enforcement lobby group was invited to be a key “stakeholder” in the process might be a clue. No medical organization was invited to be a stakeholder, even though it is they who have to deal with the awful aftermath of speed-related crashes.

It is even less clear why the limits were raised after the consultation process, since every expert safety group was against them. Opposed were: the RCMP, the B.C. Association of Chiefs of Police, RoadSafety B.C. from the Ministry of Public Safety and Solicitor General, the B.C. Ministry of Justice, Road Safety Unit, the B.C.A.A., the B.C. Truckers Association, the provincial health officer, all five regional chief medical health officers, emergency room physicians, trauma surgeons, and all B.C. road-safety researchers.

ICBC sat on the fence, but insisted that any increase be closely monitored.

The first evaluation was done a year later by independent emergency physicians and road-safety researchers from Vancouver General Hospital. They found an increase of about 10 per cent in ambulance calls for road trauma on the affected stretches of highway as soon as a year after the change. In 2016, after much delay, Stone’s ministry came out with its own report.

There were two parts. One part, an independent, rigorous analysis by world-renowned traffic engineer Tarek Sayed from the University of B.C. was relegated to the last appendix. It showed almost exactly the same results as the first study. The main report was a very colourful, and scientifically irrelevant, breakdown, road segment by road segment, of crashes, speeds, etc. The conclusion? Things weren’t so bad. Crashes had only increased on 16 of 35 road segments.

The result was rolled-back limits on only two segments and suggested engineering improvements on the other segments with more crashes.

But wait — the increases were supposed to improve safety. Apparently, this was conveniently forgotten.

Three years later, yet another independent study by Dr. Jeff Brubacher and colleagues, published last month, showed more than twice as many deaths and serious injuries on roads with increased limits. Stone pronounced the study “highly suspect” and “borderline irresponsible.” He also claimed that it may really show decreases in deaths. It does not.

There is only one “irresponsible” part of this misguided policy — the initial speed increases. Happily, the solution is easy. For the cost of a few signs, all the speed limits on the affected highways can return to their former levels. Unhappily, this will not bring back those killed nor undo the wounds of those injured as a result of this fiasco.

Dr. John Carsley, a clinical associate professor in the School of Population and Public Health at the University of B.C., is a medical health officer. Dr. Kay Teschke is a professor in UBC’s School of Population and Public Health and a road-safety researcher and advocate.

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