Truck Trailer Manufacturers Association Underride Guard Response

7/31/2019 Truck Trailer Manufacturers Association Underride Guard Response

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TTMA is an international trade association comprised of truck trailer and tank trailer

manufacturers, along with manufacturers of cargo containers, cargo tanks for trucks and

container chassis. The associate membership includes material, component, and various

service suppliers to the industry. TTMA monitors and participates in regulatory

initiatives that affect its members, but it does not design or manufacture trailers or set

standards for the manufacture of trailers. The following responses are therefore those ofthe association and not of any particular member.

Questions: The IIHS is asking NHTSA to strengthen the designs and to include

many other types of trucks that are now exempt from the regulations. NHTSA tells

us they are doing their own field evaluation now. We would like to know what this

could mean to the trucking businesses, truck drivers, and trailer manufacturers.

TTMA is aware of, and it supports, NHTSAs rulemaking and research initiatives that

seek effective ways to reduce injuries and deaths in accidents involving motor carriers,

including crashes into the rear of trailers.

This type of accident often involves driver error, so we recognize first that the rules

already in place to prevent these accidents must be followed, including laws that prohibit

driving while impaired or distracted, or driving at speeds that are too fast for the roadway

and visibility conditions presented. In addition, proper maintenance of vehicle lighting

equipment is also critical, both for passenger vehicle headlights and for trailer tail and

brake lights and the red and white retro-reflective tape that FMCSA has required by

retrofit since 2001 on the rear and sides of trailers.

Beyond prevention, TTMA supports the FMCSA requirement that motor carriers

maintain the rear impact guards that have been installed on trailers in accordance with the

federal safety standards. If a guard has been damaged, it should be repaired properly.

Bent components, poor quality repair welds or excessive corrosion can undermine guard

performance in a rear collision.

As for the IIHS petition to change the current federal safety standards, the goal must be to

make sure that any new regulation is actually effective and does not cause unintended

consequences. NHTSAs past studies have shown that serious injuries and deaths can

occur in rear crashes due to the sudden forces of deceleration that are imposed on the

occupants even without underride. These forces will necessarily increase if guards are

made more rigid. As shown in the IIHS data, fatalities have continued to occur in rear

collisions even without excessive underride. The potential for more fatalities of this type

will go up as guards are made more rigid. An unbelted occupant who strikes a dashboard

and is merely injured in a rear-end collision would strike that dashboard with a greater

and possibly fatal force if the trailers rear impact guard is made rigid. The belted

occupants who are not being injured in rear-end collisions now will also face greater risks

of deceleration injury if guards are made rigid. These are real world scenarios, and for

this reason NHTSA has previously rejected rigid guards.


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If rigid guards are going to be proposed again, all of the consequences must be

considered. The suggestion that rigid corner structures on trailers will save lives in offset

underride crashes may seem intuitively correct in one crash test scenario, but the analysis

must also consider deceleration injuries and deaths in all types of rear crashes into those

same proposed guards. In addition, adding structural components to trailers to support

full-width rigid guards will add weight to the trailers and necessarily require thedisplacement of some cargo onto other trucks and trailers. This would increase the

number of trucks and trailers on the nations highways and thus increase the potential for

crashes of all types involving cars and trucks, including those that result in fatalities in

non-underride crashes. More miles would be driven by heavy trucks to move the same

amount of cargo nationwide, and more crashes would occurmost not involving rear end

collisions.

Questions: Are the manufacturers working with IIHS or looking at what they have

done in terms of research? Do you oppose or agree with the proposed changes?

What would it cost to strengthen these guards, to bring them up the standard ofsafety the IIHS is proposing? What would it cost to add them to all the trucks on

the road as they are proposing? Should it apply to all truck trailers on the road?

The current NHTSA safety standards for rear impact guards are based on dozens of crash

tests that are not mentioned in the IIHS report. The recent crash tests by IIHS will add to

the accumulated knowledge about the risks of underride injuries, but they have not led

IIHS to propose any specific strength or energy absorption criteria for rear impact guards

only the IIHS opinion that guards should be more rigid than any of the guards it tested.

Since neither IIHS nor NHTSA has issued any specific proposal to change the

regulations, TTMA is unable to respond to any proposed change. The feasibility and

costs of a proposed change, and whether it should apply to all trailers, cannot be

determined until the specific change is proposed.

Questions: The IIHS says they have seen design changes by some of the

manufacturers guard design already. Is this a result of the crash testing and results

they have obtained? Is there a better solution?

TTMA is not sure what design changes IIHS is referencing and therefore it cannot

respond. TTMA does note, however, that trailers are highly customized and a customers

component selections on items such as tire size, wheel type, suspension type, subframe

flooring, rear frame and door type, will often affect the rear impact guard design, even

within the same trailer model line. In addition, trailers manufactured for use in Canada

have to comply with rear impact guard standards that are different from those in the

United States. So there are many reasons why guards may appear different, and these

differences may well have nothing to do with the IIHS.

As for other solutions, TTMA certainly hopes that the 1998 safety standards willeventually be shown to have reduced the number of lives lost in underride accidents. The


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recent NHTSA study suggests there has been a benefit, and we know that the crash tests

conducted by NHTSA before implementing these standards predict benefits at closing

speeds up to 30mph. High closing speeds present greater challenges, as do rigid guards

as noted above, and NHTSA has recognized that no guard will be perfect given the vast

array of possible crash scenarios (vehicle type, speeds, angles, offsets, etc.). Crash

avoidance technologies are being developed for passenger vehicles, and these may helpprevent all kinds of crashes, including rear-end collisions involving vehicles of all types.

Documents

Truck Trailer Manufacturers Association Underride Guard Response