NHTSA Proposes to Affirm Canadian Underride Standard

Q: When’s the best time to pass a rule? A: When nearly everyone already complies! While it puts you at the trailing edge of safety, it diminishes the intensity of the opposition – so it’s all good. Such is the state of a National Highway Traffic Safety Administration proposal to upgrade the Federal Motor Vehicle Safety Standards 223 and 224, for rear impact guard and rear impact protection, respectively.

The agency is proposing to align the two U.S. standards with the eight-year-old Canadian standard for rear impact guards. The proposal represents the first major upgrade to the rear impact protection standards for trucks in 21 years. It has been so long since NHTSA has addressed the current standards’ weaknesses, that an estimated “93 percent of new trailers sold in the U.S. subject to FMVSS Nos. 223 and 224 are already designed to comply with CMVSS No. 223.”

The proposed upgrade would mandate that rear impact guards meet new strength requirements at several test locations. Specifically, the current quasi-static point load test at the area around the guard’s vertical support location would be replaced by a uniform distributed load test of 350,000 Newtons (N). The performance requirements would mandate the rear impact guard to resist the 350,000 N load without deflecting more than 125 mm, and absorb at least 20,000 Joules of energy within 125 mm of guard deflection. The proposal would also require that any portion of the guard and the guard attachments not completely separate from its mounting structure after completing the test.

What NHTSA did not do: lower the guard height from the current 22 inches, nor extend the standard’s applicability to currently excluded classes of truck configurations, such as wheels back trailers, pole trailers, logging trailers, low chassis trailers and specialty equipment trucks.

Russ Rader, of the Insurance Institute for Highway Safety, which has been pushing for better rear impact guards for nearly 40 years, and formally petitioned the agency in 2011 for an upgrade, said the proposal is “a good first step, because the Canadian standard is an improvement.”

“But our tests show that they could have gone a lot further,” he added. “The Canadian standard misses protection in some offset crashes, and we know that truck manufacturers can address that in a straightforward, inexpensive way and it’s not addressed in this proposal.”

A Brief Regulatory History

Rear guard protection has been a federal requirement since 1952, when the Bureau of Motor Carriers of the Interstate Commerce Commission (ICC) established regulation 393.86 which required heavy trucks, trailers, and semitrailers to be equipped with a rear-end protection device designed to help prevent underride. The regulation contained no specifics as to the device’s efficacy, but merely required the guard to be “substantially constructed and firmly attached.”

In 1967, the Federal Highway Administration, the precursor to NHTSA, attempted to begin a rulemaking to require a rear underride guard for trucks, buses and trailers, but industry fought off any substantive upgrade to the regulations for 44 years. In 1981, the agency published an NPRM amending the equipment requirement to a moderate strength guard that would permanently deform when subjected to a load of 45,000 pounds. The agency also proposed to extend the standard to most trucks and trailers with GVWR of more than 10,000 pounds, which would include heavy single-unit trucks. In the proposed rule, the rear impact guard could not have a ground clearance greater than 21.65 inches (55 cm). The trucking industry also heavily criticized this proposal, submitting more than 100 comments. In 1992, the agency responded by proposing to split the standard in two: one for the rear guard itself, and a separate standard for the vehicle.

In 1996, NHTSA published a final rule establishing two Federal Motor Vehicle Safety Standards (FMVSS) - 223, Rear Impact Guards, and 224, Rear Impact Protection. FMVSS 223, the equipment standard, specified strength requirements and compliance procedures for rear impact guards on semitrailers. FMVSS 224, the vehicle standard, specified mounting instructions and location specifications for those guards. The final rule retained the prosed 22" guard height.  Single unit trucks were excluded from the requirements, because, the agency said, single unit trucks are far less likely to be involved in fatal accidents than combination trucks.

In 1998, the agency responded to some petitions for reconsideration and amended the Final Rule  

In the meantime, research by John E. Tomassoni, a former NHTSA safety standards engineer demonstrated the inadequacy of the U.S. rules in a series of crash tests involving rear underride guards built to reflect the then-new rear impact protection standard. The work showed that underride guards that minimally complied with the new rule were effective at impact speeds of 30 mph. But in some of the tests, the underride magnitude was such that passenger compartment intrusion occurred – in some instances, the dummy head contacted the deformed occupant compartment. And, in 2002, Transport Canada conducted a series of tests using a 1998 Ford Windstar, a 1998 Chevrolet Cavalier, and a 1998 Honda Civic,  to verify the performance of rear impact guards built under FMVSS 223/224.  It found that “none of the minimally compliant guards were effective for all three vehicle types tested.” Transport Canada effectively upgraded its standard in 2007.

The IIHS petitioned the agency in 2011. In May 2014, Marianne Karth and the Truck Safety Coalition also petitioned NHTSA to require underride guards on single unit trucks and other vehicles excluded from the current standard and to improve the standards’ requirements for all guards. NHTSA granted both petitions in July 2014, saying that it would pursue rulemaking through an ANPRM pertaining to rear impact guards for single-unit trucks and “other safety strategies not currently required for those vehicles” and a separate NPRM to upgrade FMVSS Nos. 223 and 224.

In July 2015, the agency published the advanced notice of proposed rulemaking regarding underride protection for single unit trucks.

IIHS and Karth Petitions

The IIHS has been researching various aspects of the issue, from determining the scope of the problem to developing a new underride guard. In 1977, it launched a program to develop a lightweight and effective guard that might serve as a prototype. Researchers designed and tested two guards and concluded that it was feasible to achieve substantial improvements in underride protection without significant increases in the weight of underride protection devices.

IIHS also performed a series of crash tests to determine which underride guards perform better than others and under various crash speeds and configurations (head-on and off-set) and to determine what types of failures occurred.  Testing was done using the Chevy Malibu into trailers that were certified to Canadian and U.S. requirements.  In general the testing found that the Canadian guards performed significantly better, and that there are fundamental weaknesses in the guard attachments which don’t have to be tested as a whole system. 

In 2011, the IIHS petitioned the agency to upgrade the rear impact protection standards because “the 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 regulatory and consumer information frontal crash test programs.”

In support, the Institute used the Large Truck Crash Causation Study, a federal database of roughly 1,000 real-world crashes in 2001-03.  The organization examined crash patterns leading to rear underride of heavy trucks and semi-trailers with and without guards and found that underride was a common outcome of the 115 crashes involving a passenger vehicle striking the back of a heavy truck or semi-trailer. Only 22 percent of the crashes didn’t involve underride or had only negligible underride, which they indicated was consistent with prior studies. The study noted that “In 23 of the 28 cases in which someone in the passenger vehicle died, there was severe or catastrophic underride damage, meaning the entire front end or more of the vehicle slid beneath the truck.”

IIHS also pointed to the regulatory gaps that allow some heavy trucks to forgo guards altogether and if they are on trucks exempt from the regulations, the guards don’t have to meet 1996 rules for strength or energy absorption.

In its petition, the IIHS asked NHTSA to consider: substantially increasing the quasi-static force requirements, move the one of the test locations farther outboard to address offset crash protection; require that attachment hardware remains intact throughout the tests; require guards be certified while attached to the trailers for which they are designed; investigate whether the maximum guard ground clearance can be reduced; and reduce the number of exempt truck and trailer types.

Marianne Karth became an activist for truck underride safety after a horrific underride crash that killed two of her nine children. In May 2013, Karth was on a Georgia highway approaching slowed traffic, when a semi trying to switch lanes hit the Karth vehicle in the rear, sending it underneath another tractor trailer.  Karth’s 17-year-old and 13-year-old daughters died in the crash.  One year later, Karth and the Truck Safety Coalition presented NHTSA with its petition and 11,000 signatories acquired online. Their petition asked for the Secretary of Transportation to raise the minimum level of insurance for truck drivers, for a final rule on electronic logging devices to reduce truck driver fatigue; and to improve the rear underride guard rules.

In July 2014, NHTSA granted the Karth petition without mentioning the IIHS at all. In July 2015, the agency published the separate ANPRM to consider conspicuity and rear impact guard standards for single unit trucks.

The Proposed Rule

According the NPRM, NHTSA’s interest in improving this rulemaking goes back to 2009 when the agency evaluated a study showing that fatalities were still occurring in frontal crashes “despite high rates of seat belt use and the presence of air bags and other advanced safety features.”  NHTSA’s review of cases in model year 2000 or newer vehicles in the Crashworthiness Data System of the National Automotive Sampling System found 14 percent were underrides into single unit trucks and trailers.  In 2010, NHTSA published another study analyzing the effectiveness of trailer rear impact guards, which showed what Tomassoni demonstrated more than a decade earlier: FMVSS 223 and 224 rear impact guard had had no impact on fatality rates.  

Now that the agency’s interest has been translated into action, it is only inclined to increase the force and energy absorption requirements without lowering the guard height or bringing other types of trucks into the standard. In the former case, NHTSA said that the issue was discussed extensively in 1996. Public comments, vehicle geometry, heavy vehicle operations, and crash test data led the agency to conclude that it would present an undue burden to industry. Apparently, it now is not the burden it was, because NHTSA now declines to decrease the guard height because “fleet data suggest that where possible, trailer manufacturers are voluntarily installing rear impact guards with ground clearances under 560 mm (22 inches).”

On the issue of extending the standard to other types of trucks, the agency said that its analysis showed that there are relatively few fatal rear-impact crashes involving the current excluded categories, such as wheels back trucks, and of those that do occur, many are at speeds that are not survivable – with or without an underride guard

Rader says that the Institute will continue its work on better rear impact guards, despite the gaps in the NPRM.

 “From our standpoint, we know that the trailer manufacturers will need to deal with offset crashes,” he said. “We plan to continue testing – we want to work with trailer manufacturers to go beyond the Canadian standards. We’ve gotten tremendous cooperation, and we are working with Marianne Karth to set up an underride round table to discuss further steps.”  

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