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A Major Trailer Hitch

The American National Highway Traffic Safety Administration (NHTSA) has an insatiable appetite for truck regulations these days, and a group of insurers is urging the agency to add one more to its "to do" list.

In a recent letter to NHTSA boss David Strickland, the Insurance Institute for Highway Safety (IIHS) called on the U.S. government to beef up certification standards for underride guards on trailers.

Among other changes, the Institute wants a "substantial increase" in the quasi-static force requirements of underride guards.

"Current standards allow underride guard designs that fail catastrophically when struck by passenger vehicles at speeds that frequently produce minimal intrusion and injury risk in other consumer frontal crash tests," says Institute president Adrian Lund.

The insurers say passenger-vehicle front-impact protection has advanced tremendously since the 1970s, but deadly underride crashes haven’t really slowed.

"Cars’ front-end structures are designed to manage a tremendous amount of crash energy," he continues. "Hitting the back of a large truck is a game changer. You might be riding in a vehicle that earns top marks in frontal crash tests, but if the truck’s underride guard fails -- or isn’t there at all -- your chances of walking away from even a ­relatively low-speed crash aren’t good."

The institute recently conducted a series of rear impact crash tests (see video at http://tinyurl.com/IIHStest) evaluating three different semi-trailer guards, all of which failed to varying degrees in certain crash scenarios.

The idea that new trailers out on the highway might be susceptible to severe underride crashes got a lot of exposure right away, including some typically sensationalist media coverage. ("Death by Truck Guillotine" -- ABC Online News -- might have been the worst headline of the bunch until, as Today’s Trucking first pointed out on Twitter, they revised it a few hours later to something with far less hyperbole.)

The six tests, which had a 2010 Chevrolet Malibu hitting the back of the trailers at 35 mph, show that Wabash performed the best out of the three brands overall. The Wabash and Vanguard National units were certified to more stringent Canadian Motor Vehicle Safety Standards.

While Hyundai’s and Vanguard’s guards sheared their attachment bolts and broke off when hit by the car straight on, the Wabash guard stayed in place and absorbed much of the crash energy. "In the real world, this would be a survivable crash," says Lund. "It’s clear to our engineers that Wabash understands how underride guards and trailers work together as a unit instead of treating them as separate components."

However, things appear to change when the car impacts from a non head-on angle. The Institute also ran "offset" tests to see what happens when the car hits with only part of its front. Again, Wabash performed reasonably well in a 35-mph test with a 50-percent overlap while Vanguard National and a Hyundai allowed "severe" underride, according to the study. But at 30-percent overlap at the same speed, the Wabash trailer guard bent forward and also allowed severe underride.

Had these been real-world crashes, "there would be no survivors," Lund says.

Nearly half of passenger vehicles involved
in underrides are classified as

According to the final report, "this test shows that even the strongest guard left as much as half of the rear of the trailer vulnerable to severe underride.

"The guard only worked as intended when the striking car engaged the center."

Specifically, offset tests stressed the guards’ "unsupported" outboard ends which are furthest away from the vertical frame supports that attach the guards to the trailer chassis.

When asked for more details about the testing, Institute spokesman Russ Rader confirmed that the trailers involved were brand new and the center and offset tests were performed once on each trailer. In other words, Rader says, when an underride occurred, it happened on the first attempt.

Today’s Trucking sought interviews with all the manufacturers whose products were involved in the tests as well as several other trailer suppliers and custom builders. Wabash was the only supplier to respond with this prepared statement:

"Wabash National designs and tests the safety performance of the trailers we manufacture to ensure they meet, if not exceed, government highway safety regulations. This reflects our organization’s commitment to safety, innovation and continuous improvement."


NHTSA estimates that about 423 people in passenger vehicles die each year when their vehicles strike the backs of large trucks. More than 5,000 car occupants are injured.

The insurers claim that an underride occurs in half of fatal crashes between large trucks and cars. DOT figures don’t reflect that, so, naturally, the Institute says underrides are underreported.

Whatever the rate, there’s no doubt it’s not a pretty sight when it does happen. Nearly half of the passenger vehicles that have underrides are classified as "severe" or "catastrophic" crashes, says the Institute.

Based on the optics alone, it’s not out of the question that NHTSA might eventually act in some way. Not only has it been more aggressive in monitoring truck-safety rules as of late, but it has worked with the Institute in drafting the standards that are currently in place.

Plus, it should go without saying, that studies like this provide ammo to opportunistic trial lawyers whether the guards are lawfully in compliance or not.

Specifically, the association is urging regulators to require that guards be able to absorb a bigger impact of crash energy and that attachment hardware remains intact during such tests.

As well, the Institute wants NHTSA to investigate the possibility of reducing the maximum ground clearance at the rear of the trailer and whether the standards can be extended to more trucks and trailer types like straight trucks, which mostly have guards, but are exempt from testing standards. (A regulation dating back to 1952 states only that that bumpers on these trucks "are to be substantially constructed and firmly attached").

The Institute’s research states that the attachment between guard and trailer on these units can be weak, especially in overlap crashes. Dump trucks represent a "particularly hazardous category" of straight truck, says the Institute, accounting for about a third of the segment, but more than half of severe underrides.

Additionally, the Institute calls for NHTSA to require that the trailer, underride guard, bolts, and welding be tested as a whole system with the trailer it was designed for.

"That’s a big part of the problem," Lund says. "Some manufacturers do test guards on the trailer. We think all guards should be evaluated this way."

Don Moore, director of the Canadian Transportation Equipment Association (CTEA) says his members already follow such a guideline and imagines that many major U.S. suppliers comply with similar policies.

"As a manufacturing body, CTEA specifically stresses that point," he says. "As part of our program, it is very clearly spelled out that they have to look at the structure that it’s being mounted to… when considering the impact as part of the trailer it was designed for."

As for offset collisions, Moore admits he’s not sure how much research is currently available, but as a group the CTEA is interested in discussing the latest information with its members as well as Canadian regulators.

Transport Canada, though, appears relatively satisfied with the standard as it is. A technical expert familiar with the regulation could not be made available for an interview, but a Transport Canada spokeswoman informed us that Canada’s much tougher level of protection is based on "extensive research" that considers, among other things, the complete size and mass of the guard.

So, the "results and analyses presented in the IIHS report do not introduce sufficient new information to cause the department to reconsider its original intentions."

When asked about offset impacts, Transport Canada said their tests didn’t include such collisions because they require only part of the guard to absorb the collision energy, "which is not possible in higher speed collisions." As well, the agency hasn’t seen any "evidence from ­collision investigation studies that suggest offset collisions are common events."

The sheer David-and-Goliath physics involved in such incidents may have some people wondering (rightfully, in many cases) whether an impermeable guard is even possible and -- since truck drivers are hardly, if ever, at fault in underride collisions -- that better car driver awareness and training is the more effective prevention strategy insurers should be focused on.

"So, we punish the trucking company and the trailer manufacturer for the ignorance of the car driver who was driving carelessly," says Lawrence C. Hartung, director of safety at deBoer Transportation in Wisconsin.

"If this becomes law, then every car driver’s insurance rates should be raised to cover the cost to reinforce the ICC bumper," he says not-so-jokingly.

"You can only do so much with equipment modification. Some day it will have to be realized that some of the burden of safety has to be placed on the drivers, and not the equipment." 

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Well, if you look at behaviour of other drivers these days, you're looking at plenty of potential for criticism. Now, instead of focusing on ICC bumpers, why not focus on agressive and tailgaiting drivers? I was once rear-ended by a vehicle that spun out of control due to another driver's idiodicy and the rear guards stood well.

School buses don' t have a rear impact guard. As a matter of fact, if someone rear-ends a school bus, chances are they will lose their life. If a 4 wheeler rear ends a school bus, that driver of the said vehicle is deemed to be a reckless driver. While if a 4 wheeler rear ends a semi-trailer and loses his or her life, she/he is deemed a martyr?!???