by Fred Nix

Part II of a series

Why do trucks crash and what happens when they do? These sound like simple questions and maybe they are. But, surprisingly, there is an awful lot that is not known. That’s critical because in both Canada and the US ambitious new goals have been announced to reduce the number of truck crashes over the next few years.

Transport Canada and the provinces have recently said they are going to reduce by 20 percent the number of road users killed or seriously injured in crashes involving commercial carriers – mostly truckers, although buses are also included in Transport Canada’s “commercial.” In the US, the Federal Motor Carrier Safety Administration (US Department of Transportation) has announced a goal of reducing the number of truck-related fatalities by 50 percent and the number of persons injured in truck crashes by 20 percent by 2010.

These are ambitious goals indeed. But government officials in both countries will have a hard time meeting them if they don’t first develop a full understanding of truck crashes.

While both countries collect information on truck crashes, none of it is really good enough to provide the answers to many questions about these unfortunate occurrences. The information that is available (see Graph 1 on page 20) suggests things are getting better. In Canada, where consistent information on truck crashes is available back to 1991, the number of crashes has been almost constant over the past nine years. How’s that good news? Even though there are no numbers to prove this, total truck travel has increased steadily throughout the 1990s, perhaps by two to four percent per year. So with distance driven increasing and total crashes more-or-less constant, the crash rate has obviously been falling. Ditto in the US where the number of truck crashes in the latest year available (1998) was 411,935. That isn’t much higher than the total number of crashes in 1988. The US figures on the number of crashes are, unlike Canada, an estimate so there is some year-to-year variation caused by the estimating technique. But, as shown on the chart, the overall trend appears to have been down as the US went into near-recession conditions in 1991 and then back up during the 1990s when the economy was booming.

While there are few excuses for truck crashes, it helps put things in perspective by noting that trucks are involved in relatively few collisions. In 1998 trucks represented only four percent of the vehicles involved in crashes in Canada and only 3.6 percent in the US. It is true, though, that trucks represent a higher proportion of the vehicles involved in fatal crashes – 10.8 percent of the vehicles in Canada and 8.7 percent in the US. That’s because a crash involving a truck is generally more severe than a crash involving a smaller vehicle. In fact, and this is something the anti-truck lobbies use in their propaganda, in 1998, of the 5,374 people killed on American roads in crashes involving trucks, 78 percent of the victims were people in other vehicles, mainly cars (automobiles, pickups, vans and sport utility vehicles). What anti-truck lobbies don’t tell you is that the available data also suggests it is usually the car driver at fault in a truck-car crash (see Table 2 on page 20).

Fatal crash rates for trucks in the US, at 2.5 per 100 million miles of driving, are somewhat higher than the fatal crash rate for cars (2.0 per 100 million miles). Again, this is because a crash with a truck tends to be severe. The injury crash rate for trucks is only 45 per 100 million miles of driving while for cars it is over three times higher (149).

Computing crash rates for Canadian cars or trucks is difficult because there hasn’t been any reliable estimates of distance traveled. A new survey from Statistics Canada will eventually solve that problem but, until then, only crude estimates are available. These suggest that trucks have a fatal crash rate of 2.7 per hundred million miles and an injury crash rate of 49 per hundred million miles. Both figures are slightly higher than the comparable US crash rates for trucks but, since these are crude estimates, and the US figures themselves are only estimates, they don’t prove that Canadian trucks are less safe than their American counterparts (there’s too much chance of small errors in the estimates for this).

Total crash rates – fatal, injury, property – are shown in Table 1. Here the more familiar (to Canadians) “100 million kilometres” of driving is used to compute the rates. Crash rates per 1000 registered trucks are also shown. The warning is that all of these ratios are only estimates, and this warning is particularly important in the case of the Canadian numbers. Transport Canada, which puts together the Canadian statistics on truck collisions, doesn’t calculate a crash rate per kilometre yet because it isn’t possible to relate the information on crashes with the new Statistics Canada estimates of kilometres of travel. (The figure shown in Table 1 is the writer’s own crude estimate using information on collisions from 1998 with the first estimates of distance traveled for the year 2000.) Transport Canada does compute a collision rate per 10,000 registered trucks. Its latest publication shows these rates have been falling. For tractor-trailers, the fatal crash rate fell from 21.3 to 15.8 per 10,000 trucks between 1994 and 1998 and for straight trucks it fell from 6.6 to 5.7 over the same period.

For all the hype about the safety of double and triple-trailer combinations, the US statistics show that they are actually involved in few collisions. They only account for 1.4 percent of all truck crashes. Nothing comparable is available in the Canadian statistics.

The comparison of truck drivers and car drivers in the US in Table 2 is interesting because it shows that truck drivers are more professional than car drivers. When a policeman investigates a collision, a “driver factor” can be noted on the report. This can be anything from “driving too fast,” to a report of some infraction (drugs, alcohol, etc). There are upwards of 100 “driver factors” used in the US statistics. As shown, when just considering single-vehicle fatal crashes, there isn’t a huge difference between truck and car drivers. Obviously, in single-vehicle crashes there is a big chance the driver made a mistake. But if just the fatal crashes where a truck and a car are involved are examined, it’s significant that the police show a “driver factor” in 26 percent of the cases for a truck driver but in 82 percent of the cases for a car driver. The implication, the one the anti-truck lobbies don’t talk about, seems to be that it is usually the car driver who has done something to cause the collision. The last line of the table shows that alcohol is rarely a factor in fatal truck collisions whereas close to one out of five car drivers who have been in a fatal collision with a truck were drinking.

Canadian information on drivers is a bit different than US information. For one thing, the published information only shows “commercial” drivers – this includes bus drivers as well as truck drivers. For another thing, “driver factors” are broken into two groups: “driver condition” – that is, whether the driver was sleepy, had been drinking, was inattentive or was on drugs; and “driver action” – that is, how the driver was driving immediately prior to the collision.

But, even with these differences, the numbers support the US data in showing that commercial drivers are more professional than most car drivers. In 1998, 91 percent of commercial drivers involved in fatal crashes were listed as “apparently normal” on the accident report versus only 68 percent for car drivers involved in fatal crashes. And 79 percent of commercial drivers were “driving properly” prior to a fatal crash versus only 58 percent of the car drivers.

The most telling point in the US statistics is that most truck crashes happen in good weather, on dry pavement, during daylight hours (see Table 3). Only seven percent of truck crashes occur between midnight and 6:00 a
.m., although this rises to 15 percent when just fatal crashes are considered. In Canada, 65 percent of fatal truck crashes and 74 percent of injury truck crashes occur during daylight hours, according to Transport Canada’s analysis. Transport Canada also notes that “the majority of collisions involving heavy trucks occurred on dry road surfaces.”

In the US, for about three-quarters of all truck collisions, the police note on their accident reports that the “first harmful event” was contact with another moving vehicle. In over 90 percent of all truck crashes, the police record no “driver factor” on the accident report – no apparent traffic violations, no driver misjudgments (for example, following too closely), no fatigue and no drugs or alcohol.

Canadian statistics also point to several important things. In 1998, 19.1 percent of all truck collisions were single-vehicle collisions. Some of these occur when a truck makes a right hand turn or when it backs up, but a large proportion occur when the truck is travelling forward on a straight road. This seems to suggest that driver fatigue is a problem as there are few other reasons for a truck driving off the road. Transport Canada, in an analysis of all truck accidents between 1993 and 1997, isolates fatal collisions involving single tractor-trailers. For these collisions, 78 percent occurred when the vehicle was “going straight ahead,” 48 percent occurred where the road was “straight and level,” 69 percent occurred when the road surface was dry, and 70 percent occurred where speed limits were 80 km/h or greater. Transport Canada doesn’t jump to any conclusions about driver fatigue, but there is plenty in these statistics to make the rest of us wonder about it.

The 1998 Canadian statistics also suggest that in only two percent of commercial vehicle (bus or truck) collisions is a mechanical problem noted on the accident report. That may be because police officers are not necessarily in the best position to detect mechanical problems. Detailed investigations of large vehicle collisions in Canada suggest mechanical defects may play a role in 13 percent of crashes.

Finally, on Table 4 on page 20, the most frequent types of truck collisions in Canada are noted. This information is from Transport Canada’s analysis of the 1993-1997 statistics. As shown, fatal truck crashes overwhelmingly involve two vehicles moving in opposite directions. Rear-end collisions are important in fatal, injury and property collisions, but stand out in importance for injury collisions.

All these statistics give some clues about the nature of truck collisions. What stands out, although this is making inferences about the numbers, is that driver error (either truck driver or, quite often, car driver) is the single biggest issue. But just knowing this is not enough for either Canada or the US to know how to reduce the number of collisions involving trucks. That’s one of the reasons why, in the US at least, new efforts are being made to analyze truck crashes. Perhaps Canada should follow suit.

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