Truck News


Can a Simple Formula Prevent Rollovers?

CALGARY, Alta. - Meet Grant Aune and Mike Morigeau. Both are former accident reconstructionists who say they've visited far too many tractor-trailer rollovers. Both have a broad understanding of what causes rollovers and have made it their mission...

DON'T PUSH IT: Speed advisory signs are generally intended for four-wheelers. Shave an additional 20 km/h to be safe, says Aune.
DON'T PUSH IT: Speed advisory signs are generally intended for four-wheelers. Shave an additional 20 km/h to be safe, says Aune.

CALGARY, Alta. – Meet Grant Aune and Mike Morigeau. Both are former accident reconstructionists who say they’ve visited far too many tractor-trailer rollovers. Both have a broad understanding of what causes rollovers and have made it their mission to educate the industry about the dynamics of a truck rollover. And both are adamant the industry isn’t doing enough to educate its drivers about the causes of rollovers and how they can be prevented.

But for the most part, that’s where the similarities end. While Morigeau educates drivers and safety supervisors about the cause of rollovers using a simple formula, Aune prefers to take a less mathematical approach, instead focusing on load visualization. The message is the same, however: the vast majority of truck rollovers are preventable if drivers are equipped with the proper knowledge to understand the forces that cause them.

For Morigeau, understanding rollovers is as simple as understanding a formula, specifically: LA=V2/Rg (Lateral Acceleration = velocity squared divided by the radius of the corner multiplied by gravity). LA represents lateral acceleration which is expressed in terms of G-forces. It’s a factor that’s measured by calculating speed and the radius of any given turn (R). While it sounds complicated, Morigeau has developed a course he says clearly explains the formula and its implications.

“The trucker has to know how fast he is going and how many G-forces are at work on his rig,” explains Morigeau. “How do we take all these complicated physics and bring it down to where a driver can understand? Well, I think I’ve accomplished it.”

The former driver trainer delivered his program to a large trucking company in the U.S. that was experiencing a high rate of truck rollovers. After explaining the formula to the company’s safety supervisors, the fleet went from having 42 rollovers the year they called Morigeau, to just nine the following year.

“They had a problem, we addressed it and they resolved it,” recalls Morigeau. “When you reduce your rollovers by 33 crashes at US$50,000 per crash or more, you’ve made a pretty substantial savings and that goes right to your profit margin.”

Morigeau doesn’t hold back on his criticism of the Canadian trucking industry for failing to address what he calls an epidemic of truck rollovers.

“In the U.S. they’re very proactive as opposed to reactive,” says Morigeau. “I went to the (Canadian) trucking industry four to five years ago and said ‘Will you endorse this program so every new driver coming into the industry would be familiar with rollovers and what causes them?’ Their response at the time was ‘We don’t want our drivers to know how fast they can go around the corner.’ If they don’t know how fast they can go around the corner, we’re putting our head in the sand and ignoring the problem.”

Aune, senior partner with Advantage Fleet Services in Vancouver, B.C. agrees the industry must do more to reduce the number of truck rollovers occurring each year.

“One of the incidents that are almost rampant within the transportation sector are rollovers,” Aune explains. His company has developed a 2.5 hour Standard of Care program that explains, in layman’s terms, the forces at work on a load and how drivers can avoid potentially fatal accidents.

“I have drivers think about the stability base of their vehicle as being a triangle,” says Aune.

The base of the triangle extends from the outside wheels on the most rearward trailer, and the top point of the triangle is the top of the load.

“They have to visually think about where their center of mass is,” says Aune. “For a logging truck driver it’s easy because they can look at all the logs on the back. For a guy operating a deck where he can see the load, he can visualize where the center of mass would be and that’s what we focus on. If the triangle is oddly shaped, they’re going to run into problems because they’re going to be advantaged on some curves and disadvantaged on different curves.”

An abnormally tall triangle suggests a load is unstable “and as a result you have to be more cautious of the advisory speed signs,” adds Aune.

“Remember, they’re posted for cars, not for tractor-trailer units,” he says.

Aune suggests shaving about 20 km/h off the advisory speed when entering a corner, just to be safe.

Both Morigeau and Aune agree speed is the number one cause of truck rollovers. There are other primary causes as well, as outlined by Aune here from least common to most common:

Suspension, tire or load defects such as a tire failure: The incident changes where the center of mass lies and makes the vehicle vulnerable to rollovers.

Vehicle is ‘tripped’: An object impedes the path of the tire.

Soft shoulders: This is often attributed to fatigue, when a driver slides onto a shoulder, changing the center of mass of the vehicle. The rollover often occurs when the driver tries to bring the truck back onto the paved surface.

Steering induced: The driver has to make some additional steering input, for instance when trying to avoid an animal on the highway.

Speed: By far the number one cause of truck rollovers is simply driving too fast for the conditions on any given corner.

While speed may be to blame for the vast majority of rollovers, that’s not to say a truck can’t be flipped on a seemingly harmless corner while travelling below the posted speed limit (remember, speed limits are calculated for four-wheelers, not truckers). Take for example the trucker who has driven through a corner 100 times hauling a commodity with a low center of mass such as steel pipe. That same driver would have to lessen his speed accordingly if hauling hanging beef or other freight that has a radically different center of mass.

Understanding the characteristics of the commodity you’re hauling is an important factor in calculating a safe speed at which to navigate a corner.

Morigeau also suggests drivers should be constantly on the lookout for telltale signs of trouble. For example a corner that has tire marks on the pavement or recently replaced guardrails has clearly been the site of an accident in the past, so it doesn’t hurt to slow down a little bit more and treat that corner with more respect.

Many experienced drivers may feel they have developed a sixth-sense about how quickly they can safely navigate any given corner, but surprisingly it’s the experienced driver that causes the vast majority of rollovers.

Advantage Fleet Services did a study in B.C. that examined 10 years of rollover data within the province’s interior.

“We found it wasn’t the green, young inexperienced driver that was rolling trucks over, it was the seasoned veteran who was pushing the envelope,” says Aune. “He’s been over the road many, many times before and had a pretty good idea what speed he could go around any given curve so he was pushing the edge and for whatever reason something had changed relative to his load.”

Morigeau suggests most rollovers are caused by drivers with more than three years of driving under their belt.

“You’ve got some confidence now, you’ve got a couple of winters under your belt and now you’re starting to hurry so you can make better time and all of a sudden you’re racing,” he explains. “The highway changes daily. We can never lose respect for the highway or the equipment we’re driving.”

With the average rollover costing CDN$100,000 or more, the industry has a vested interest in taking steps to equip its drivers with the knowledge they require to understand how to prevent them. Is the industry doing enough in this regard? The answer from Aune and Morigeau is unanimous: and it’s a resounding NO.

“The majority of rollovers are preventable but why are we not giving our drivers the knowledge to prevent them? We know that today’s truckers have to be a little more educated than they have in the past. Let’s not think they’re all Neanderthals, which is ridiculous,” says Morigeau.

“We give them fuel, we give them very expensive rigs – why are we not giving them knowledge? I get tired of looking at dead bodies.”

Adds Aune: “If there is one solutio
n to the whole problem of rollovers it’s understanding the concept of it, knowing how it happens, and slowing down.”

For information about Aune’s Standard of Care program, call 1-866-433-2374 or visit For details about Morigeau’s Commercial Vehicle Rollover Dynamics Program, call 1-780-478-7940.

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