Interpretation ID: 18764-1.pja
Mr. Paul Irby
President
Innovative Trailers, Inc.
714 Falvey
Texarkana, TX 75501
Dear Mr. Irby:
This responds to your letter requesting an interpretation of whether the chip trailers your company manufactures would be excluded from the National Highway Traffic Safety Administration's (NHTSA's) rear impact protection (underride guard) regulations. Although your letter was labeled and written as a petition for rulemaking, in a telephone conversation you told Mr. Michael Huntley in our Office of Safety Performance Standards that your intention was to get an interpretation of whether your trailers meet the definition of an excluded special purpose vehicle. Accordingly, your letter was forwarded to this office for a legal interpretation. As explained below, these trailers are not excluded as special purpose vehicles, so an underride guard complying with our regulations would have to be supplied.
These trailers are essentially van-type trailers that carry wood chips. They are unloaded by driving the tractor and trailer onto a long platform that is then hydraulically tilted at an angle of about 60 degrees so that the wood chips slide out the rear of the trailer. In order to support the great weight of the trailer, its load, and the tractor in the tilted position, all of your trailers have a very rigid rear guard which you state mates with some sort of handling equipment on the platform. The guard's horizontal member is suspended below the rear of the trailer by two pieces of heavy steel plate welded perpendicularly to the back of the trailer. These plates are located a few feet outboard of the trailer centerline and oriented in a vertical plane parallel to the trailer sides. The vertical rear surface of the plates forms the rear extremity of the trailer and project's a few inches rearward of the guard. You explain that most of your trailers are excluded wheels-back vehicles, but that a small number (5%) of your trailers have moveable undercarriages, and therefore cannot qualify as wheels-back vehicles. You state that you do not know how to design a guard that meets the energy absorption requirements of S5.2.2 of Standard No. 223, while providing sufficient rigidity to meet the handling requirements of the offloading ramps.
Federal Motor Vehicle Safety Standard No. 224, Rear impact protection, requires most trailers and semitrailers weighing over 10,000 pounds to be fitted at the rear with a rear impact (underride) guard meeting the requirements of Standard No. 223, Rear impact guards (49 CFR 571.223 and 571.224, published on January 24, 1996 at 61 FR 2004). However, certain kinds of vehicles are excluded. The only excluded categories that are relevant for the purposes of this letter are wheels-back vehicles and special purpose vehicles.
The analysis in your letter is correct regarding the wheels-back status of your trailers. Wheels-back vehicles, excluded by S3 of FMVSS No. 224, are defined in S4 as a "trailer or semitrailer whose rearmost axle is permanently fixed and is located such that the rearmost surface of [the tire] on that axle is not more than 305 mm forward of the transverse vertical plane tangent to the rear extremity of the vehicle." The threshold issue is whether the rear wheels are permanently fixed. If the rear surface of the rear wheels is within 305 mm of the trailer rear extremity, you are correct in assuming that most of your trailers with fixed rear wheels are excluded. However, your trailers with rear tandems that are not permanently fixed are not excluded as wheels-back.
We turn to the question of whether the wood chip trailers with adjustable undercarriages are excluded as special purpose vehicles. A special purpose vehicle is defined in S4 of FMVSS No. 224 as "a trailer or semitrailer having work-performing equipment that, while the vehicle is in transit, resides in or moves through the area that could be occupied by the horizontal member of the rear underride guard, as defined by S5.1.1 through S5.1.3."(1) The guard is the only part of your trailer that, while the vehicle is in transit, resides in the area that could be occupied by the rear underride guard. Therefore, it would have to be considered work-performing equipment for the trailer to be excluded.
There is no definition in the standard for "work-performing equipment." In determining the meaning of regulatory language, the first place the agency looks is the plain meaning of the words. In the context which is relevant to this safety standard, "work" is defined as "the transfer of energy from one physical system to another; especially, the transfer of energy to a body by the application of force . . ." "Perform" is defined as "to begin and carry through to completion; do." American Heritage Dictionary of the English Language, 1971. Taken together, NHTSA interprets the words "work-performing" to mean that the equipment must actively perform its function, and that the function must involve exerting force or moving something else. The guard on your chip trailers does not perform work in this sense. Its function is to connect to the unloading equipment and possibly to support the tilted trailer while unloading. Therefore, the guard is not work-performing equipment, and the bottom dump trailer does not meet the definition of a special purpose vehicle. An underride guard would have to be provided on this vehicle.
We cannot provide a specific opinion on how your trailer should be redesigned to accommodate a guard. We note, however, that the standard specifies only the guard's horizontal member position, and therefore there is a great deal of flexibility in how you attach the guard to the trailer, so long as the strength and energy absorption requirements are met. There is no requirement that the guard be integrated with or suspended from the plates at the rear. We noticed in your photos that the plates comprise the rear extremity of the trailer (and therefore would comprise the lower extremity when the trailer is tilted). We also noticed that the rear edge of the plates show more wear than the guard. These two observations cause us to wonder whether it is actually the guard, or the plates that the guard is suspended from, that support the trailer when it is tilted. If it is the plates themselves that support the vehicle, you might be able to keep the rigid plates and still have a compliant guard if you mount the guard so that it acts independently from the rigid plates. If necessary, you could mount the guard up to 305 mm forward of the rear edge of the plates. These observations are for your consideration, and are not intended as an endorsement of a particular solution. It is you, as the vehicle manufacturer, who is responsible for the vehicle's compliance with the standard.
If you have difficulty meeting these requirements, the agency would consider a petition for temporary exemption from Standard No. 224. Under one of our regulations (49 CFR Part 555), vehicle manufacturers may apply for a temporary exemption from the Federal motor vehicle safety standards. Under Sec. 555.6(a), a manufacturer whose yearly production is not more than 10,000 units may ask for an exemption of up to three years on the basis that compliance would cause it substantial economic hardship and that it has attempted in good faith to comply with the standard from which it has asked to be excused. We have enclosed a copy of Part 555 for your information. We have also enclosed a copy of our regulations relating to the protection of confidential business information. Most of the trailer manufacturers submitting petitions for temporary exemption have requested that their financial information remain confidential.
Please note Part 555 requires the agency to publish a notice in the Federal Register seeking public comment on each exemption petition before a decision can be made on such a request, and then publish a second notice either granting or denying the petition. This process normally takes three to four months from the date of submittal.
If you have any further questions, please feel free to contact Paul Atelsek of my staff at this address or by telephone at (202) 366-2992.
Sincerely,
Frank Seales, Jr.
Chief Counsel
d.7/17/98
ref:224
1. Note that this definition, as quoted, reflects an amendment made in response to petitions for reconsideration of the final rule. See 63 F.R. 3654 (January 26, 1998).