TORONTO — Last time we went through this, it was the Yanks introducing a new under-ride guard for trailers. In 1998, the National Highway Traffic Safety Administration (NHTSA) introduced mandatory standards for design, construction, and functionality of what was once known as the “ICC Bumper.”

The goal of a rear impact guard is to arrest the forward motion of a passenger vehicle when striking the rear of a trailer, thus preventing or minimizing a damage pattern called “under-ride with passenger compartment intrusion” (PCI). Nasty accidents those, often resulting in decapitation and other morbidities.

Canadian regulators published new and more stringent under-ride guard requirements for trailers registered in Canada in October 2004, and the rules come into effect September 2007. Meanwhile, NHTSA is re-evaluating its under-ride guard requirements, and are expected to announce a new rule in the near future — most likely one that will mirror the Canadian guard. How’s that for a change?

These rules will include a requirement for a horizontal crossmember that is closer to the ground, and remains that way even after impact, to prevent the car from going too far under the rear of the trailer body. There’s also specific requirements for energy absorption, deflection of the guard under impact, and other necessities that render the guard capable of its daunting mandate.

Operators will need to develop maintenance programs to
preserve the functionality and integrity of the under-ride guard.

With implementation a few months off, and the engineering work well under way, questions are beginning to surface that may have some impact on the owner of the vehicle. You buy the trailer, presumably certified from the dealer, but how will the liability for the guard shift when you sign the ownership papers?

Eddy Tschirhart, director of technical programs at the Canadian Transportation Equipment Association (CTEA) said there will be some liability issues for the end user when the rules come into force.

“We’re not sure yet how this will be enforced at roadside, but we know from the American experience that liability for the structural integrity of an in-service guard may be the operator’s,” Tschirhart says. “We see it becoming a maintenance item, at least, and even then, the operators will need to be very careful about how they repair damaged guards.”

The guard is designed to withstand certain impact forces of 350 kN in a uniform load test, and to absorb 20,000 joules of impact force. Whatever that means in lay terms, it’s doubtful that Buddy down the road at Joe’s Welding will be qualified to slap a piece of 4-in. square tubing to the bumper and call it fixed.

Possible deformation from “dock-lock” encounters is certainly going to be a concern, as will corner damage from strikes with terrain, or lamp posts or other hazards. Minor rear-end collisions could compromise the engineered strength and absorption capabilities of the guards, and certainly, any unauthorized modifications will affect the guard.

Ray Camball of Trailmobile Canada says many trailer makers will be offering customers a choice of weld-on or bolt-on under-ride guard assemblies. Designs may vary from one OE to another, but if they meet the requirements, they’ll be appropriate.

Now would be a good time to start asking questions of your trailer supplier. If you need to re-think your trailer options, you’ve still got five months to do it.

The new standards will apply to all trailers built for registration in Canada after September 1, 2007 with the rear axle set any distance forward of the rear of the trailer. Any configuration that has a rear axle directly at the rear of the trailer body, or has an assembly at the rear of the trailer that would prevent a PCI ­incident, will likely be exempt.

Examples could include, the lead trailer of a Super-B combination, a float trailer, or a trailer with a fork-lift stowed at the rear of the trailer. Straight trucks are not included at this point in time.