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NHTSA defends new standard for truck trailer underride guards

Former agency chief says new regulation amounts to 'regulatory malpractice'

94% of trailers already meet the new standard, according to NHTSA. (Photo: Wabash National)

The National Highway Traffic Safety Administration is upgrading safety standards on rear underride protection on tractor trailers to help prevent crashes involving passenger vehicles, but safety advocates say the changes do not go far enough.

In a 107-page final rule made public on Thursday, NHTSA said it will adopt requirements similar to Canada’s standard for rear impact guards. Rear guards on truck trailers will be required to “provide sufficient strength and energy absorption to protect occupants of compact and subcompact passenger cars impacting the rear of trailers” at 35 mph (56 km/hour).

Rear underride crashes occur when a passenger vehicle strikes the back of a generally larger vehicle and the front end of the passenger vehicle slides under the rear end of the larger vehicle.

In extreme underride crashes involving tractor trailers, the passenger vehicle can underride the trailer to such an extent that the end of the trailer enters the passenger compartment of the colliding vehicle, severely injuring or killing occupants of the car. Underride guards mounted on the rear of trailers can prevent serious injuries and deaths resulting from underride crashes.

The final rule, which makes no substantive changes to the proposed rule that preceded it in December 2015, will improve protection in crashes in which a passenger car hits the center of the rear of the trailer, according to NHTSA, and in which 50% of the width of the passenger motor vehicle overlaps the rear of the trailer.

“NHTSA’s priority is the safety of everyone on our roads,” commented NHTSA Administrator Steven Cliff. “This new rule will improve protection for passengers and drivers of passenger vehicles while also meeting a critical mandate from Congress under the Bipartisan Infrastructure Law.”

Passenger protection technologies in vehicles striking trucks will be able to absorb enough of the crash forces from the impact to “reduce significantly” the risk of fatality and serious injury, according to the final rule.

Because an estimated 94% of applicable trailers already have compliant guards, according to NHTSA, the annual average incremental fleet cost of equipping the remaining applicable trailers with compliant rear impact guards is estimated to be $2.1 million in 2020 dollars. The added average weight of 48.9 pounds per vehicle that the guards add would result in an estimated annual fleet fuel cost of approximately $4.43 million and $5.59 million, discounted for inflation at 7% and 3%, respectively.

Advocates for Highway and Auto Safety (Advocates), which had sought much more stringent underride requirements, was “deeply disappointed” by NHTSA’s final rule, particularly after the agency’s data recently revealed that large truck fatalities are on the rise.

“Unfortunately, today’s action allows trucking companies to choose a less safe course of action at the expense of road user safety,” said Advocates President Cathy Chase on Thursday.

Joan Claybrook, a safety advocate and a former NHTSA administrator, said it would have been better had the agency not acted at all.

“This final rule…amounts to nothing less than regulatory malpractice,” Claybrook said. “Instead of improving protections to reduce underride fatalities and injuries, the agency has gone backward by issuing a rule that 94% of trailers already meet. As such, NHTSA has lowered the bar on public safety instead of ensuring it. This is an affront to the families of underride victims who have been working so hard to have the standard updated.”

In developing its rule, NHTSA had considered a standard in which rear impact guards withstand a 35 mph crash of a passenger vehicle into the rear of a trailer wherein only 30% of the width of the passenger vehicle overlaps the rear of the trailer.

The agency asserted however, that available data related to this standard — which would have required a modified rear guard and therefore more costly for the industry overall — do not show such a standard “would be reasonable, practicable, or appropriate” for vehicles subject to the regulations.

“Accordingly, NHTSA cannot conclude that a federal mandate for such a requirement for all trailers is warranted at this time.”

The rule is effective 180 days after publication in the Federal Register, with a compliance date of two years after Federal Register publication. Petitions for reconsideration must be received no later than 45 days after publication.

Click for more FreightWaves articles by John Gallagher.


  1. Trailblazer

    You all act as if distracted tractor trailer drivers never rear end a passenger vehicle at highway speeds forcing the passenger vehicle into the rear of another tractor trailer. Happens daily and innocent passengers are permanently maimed and killed because of your equipment, the trailer, lacking sufficient safety features to mitigate the severity of the injuries. You’re performing a job, not out for a Sunday cruise, and as such should be held to higher safety standards and that includes operating equipment designed with safety in mind on the public roadways.

  2. Paul

    This all started with the fifty three foot trailers. Before the trailers were fourth five feet long and the cars and pickups run right into the back axle and wheels. Now there is more room between the rear of the trailers and the rear axle of the trailers. We don’t need more laws to change the trailers we drivers to pay more attention to there driving. I drove a truck for 45 years. Was hit five times. Destroyed three of the cars. No one was killed. Thank goodness. The other ones were minor mirror taken off hitting my trailer. Guy ran into my drive axles and kept going. Good luck out there.

  3. Art

    I don’t want to step in any college boys toes but being the vehicles are running into the back of the trailer just maybe we should look into teaching or training the driver of vehicle that ran into the trailer, why is it my expense to put guards on my equipment because you are to stupid to pay attention to what you’re doing? Sounds like democrat logic you’re using

  4. Remi

    Ok, trucks needs guards to prevent cars and small SUV going under the trailer, but how about SCHOOL BUSES they are on the same height Is truck trailer and none of school busses don’t have anything to protect passenger cars and SUV. Maybe NHTSA will look into.

    1. Art

      No trucks don’t need guards and the owners don’t need the expensive costs putting them on, you need to learn to drive better pay attention more , it’s not the truck owners responsibility to make sure your phone isn’t in your hands and your eyes are on the road and what’s around you

  5. Brian

    The real problem is that it takes 107 pages to describe this rule. Seriously? Look at all the regulations manufacturers already have to meet. The NHTSA, DOT, FMVSS and EPA rule books combined would look like a set of encyclopedias if printed out, the sum of which would crush a human foot if dropped on. This is bureacracy run amok, and no one has the moral fortitude to finally say ENOUGH.

    1. Adrienne Bonne

      It’s easy to solve. Get people to stop texting while driving. Or how about when the mobile phone sees its going over 10mph, it shuts down.

  6. Jesus Mejia

    All these accidents can be boiled down to three words…ME FIRST ATTITUDE. Everyone wants to beat out the vehicle out in front. There is no common courtesy on the road anymore. Not even by law enforcement. They especially seem to think they’re entitled. How many times has some of you seen a police cruiser, doesn’t matter what state, speeding excessively, tailgating, and/or commiting unsafe lane changes? Many more parked on the median where it is sometimes illegal to do so.

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John Gallagher

Based in Washington, D.C., John specializes in regulation and legislation affecting all sectors of freight transportation. He has covered rail, trucking and maritime issues since 1993 for a variety of publications based in the U.S. and the U.K. John began business reporting in 1993 at Broadcasting & Cable Magazine. He graduated from Florida State University majoring in English and business.