Trailerbodybuilders 4165 Editorial Image 1 0
Trailerbodybuilders 4165 Editorial Image 1 0
Trailerbodybuilders 4165 Editorial Image 1 0
Trailerbodybuilders 4165 Editorial Image 1 0
Trailerbodybuilders 4165 Editorial Image 1 0

Safety takes another step forward

June 4, 2016
Trailer/Body Builders May 2016 editorial

Let’s say you are not exactly paying attention as you drive, and you look up to see a truck stopped in front of you. You can’t possibly stop in time. What do you do?

Your best case is that you successfully dodge the trailer. But your worst case is that you only partially dodge the trailer.

That’s because the rear bumpers of trailers are engineered to stop you from running underneath the trailer. Crashing into only part of the bumper tends to result in only partial protection.

But new underride guards are being developed to help keep motorists safer when they rear-end a trailer. According to results of a series of crash tests now being conducted by The Institute for Highway Safety and North America’s largest manufacturers of trailers, these new designs are increasing the likelihood drivers will be able to dodge major injuries, even when they can’t quite dodge the accident.

The thing that makes the offset crash so difficult for traditional designs is that it concentrates the force of the impact where the guard is weakest—the unsupported end of the horizontal bar. In crash tests from three years ago, these guards prevented underride when the impact was in the middle of the guard—and even a 50% offset. But the unsupported piece of steel tubing of standard designs could not prevent underride in extreme offset crashes. These are guards that complied with federal motor vehicle safety standards. But IIHS tests went far beyond what is required by federal regulations.

The trailer industry went to work to design underride guards that meet the higher expectations of IIHS. The new underride guards that are being developed look a lot different than the diagram that NHTSA used in the regs to spell out the desired geometry of a guard. The new designs brace the bar from one end to the other. And the results, which we show on our website (, protect the integrity of passenger compartment—the ultimate goal of any underride guard. 

IIHS personnel offered kudos to the trailer industry following the results of the test. Later, however, came the inevitable question: What’s next? Where do we go from here? Should we shoot for a 40-mph crash speed instead of 35? What about 50 mph?

A lofty goal, but the human body can only withstand so much. What is that limit? NASA and military researchers have done some research, but there is not a very long line of volunteers for that type of physical abuse. Lateral acceleration, because the forces are unequally distributed, separates organs from one another at around 14 Gs.

A test pilot named John Paul Stapp conducted acceleration/deceleration tests on himself between 1946 and 1958, inflicting concussions, lost dental fillings, broken wrists, and white vision caused by the blood in his eyes being forced into the back of his head. He survived.

But for most of us, that type of force can be fatal. For example, one person was killed and 70 injured in 1997 when “clear air turbulence” alternatively slammed passengers deep into their seats and slammed them again against the ceiling of the aircraft. 

Should we raise the crash-test speed for underride guards? Maybe someday, but we are still convinced that the best way to prevent casualties is not by managing the forces of a rear-end collision. It’s by avoiding the collision in the first place.

According to research conducted by the University of Michigan Transportation Research Institute, 71% of fatal accidents involving trucks and automobiles were exclusively the result of actions taken by the driver of the car. The truck driver caused 16% of the accidents, and both drivers shared the blame in 10% of them. That means automobile drivers contribute to 81% of fatal truck accidents. Isn’t there some low-hanging fruit to be harvested in that orchard?

Here’s a conversation starter: How about making adaptive cruise control standard equipment? When the car has to slam on its own brakes, most drivers tend to look up from even the most important text messages. No crash. No underride. 

We applaud the work IIHS has done to improve the safety of our roads and highways. These tests, funded entirely by the IIHS, provide trailer manufacturers with valuable feedback on the real-life performance of their designs. Accolades, too, to the trailer manufacturers who have responded with new designs that are far more effective than what the regulations require. Yes, there is more work that will be done. But let’s also look more closely at driver behavior. We need to share the road. And when it comes to safety, we need to share the load.♦

About the Author

Bruce Sauer | Editor

Bruce Sauer has been writing about the truck trailer, truck body and truck equipment industries since joining Trailer/Body Builders as an associate editor in 1974. During his career at Trailer/Body Builders, he has served as the magazine's managing editor and executive editor before being named editor of the magazine in 1999. He holds a Bachelor of Journalism degree from the University of Texas at Austin.