Executive Vice President
1900 North St.
Marysville, Kansas 66508
Dear Mr. Joyce:
This responds to your letter requesting an interpretation on whether the tilt bed trailers your company manufactures would be excluded from the National Highway Traffic Safety Administration's (NHTSA) recent rear impact protection (underride guard) regulations. As shown in the product literature and videotape you enclosed with your letter, your trailers are equipped with hydraulic traveling rear axles. These axles move fore and aft under the frame rails of the vehicle in conjunction with hydraulic pistons at the front of the bed to tip the bed of the trailer down in the rear until it contacts the ground. Once tipped, containers, construction equipment, and wrecks can be driven or pulled by a hoist cable on and off the bed.
Based on your product literature and videos, it appears that your factory mounts this equipment on new truck and trailer chassis prior to first sale. You believe that these trailers are excluded due to their "special design." We assume you mean that you believe the vehicles are excluded as "special purpose vehicles," because mounting underride guards on the rear underside of the rails which would prevent them from being fully lowered. The short answer to your question is that your trailers are not excluded.
Federal Motor Vehicle Safety Standard (FMVSS) 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 FMVSS No. 223, Rear impact guards (49 CFR 571.223 and 571.224, published on January 24, 1996 at 61 FR 2004). The only excluded category of vehicle that is relevant for the purposes of this letter is special purpose vehicles.
A special purpose vehicle is defined in S4 of FMVSS No. 224 as being "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 . . . (emphasis added)." Your tilt bed trailer is not excluded, because it does not meet the definition of a special purpose vehicle. Although NHTSA considers the rails to be work performing equipment that, as the frame is tilted, passes through the area where the horizontal member of the underride guard would be located, they do not do so while the vehicle is in transit.
NHTSA addressed the issue of roll off hoist trailers in the final rule. The National Solid Wastes Management Association (NSWMA), a trade group that we believe represents many of your customers, requested special consideration for roll-off hoist vehicles. However, NSWMA's main objection was requiring guards on the containers themselves, which is not your concern. NSWMA stated in their comment that:
[t]he most common type of roll-off tilt frame used is the 'outside rail' design . . . In these cases the rear underride [guard] required by [23 CFR] 393.86 will contact the ground at a frame tilt angle of approximate [sic] 40 degrees. Since this causes instability if the ground is uneven, a number of manufacturers have resorted to a retractable underride [guard] design, where a strut attached to the rear chassis frame will cause the underride [guard] to move forward and out of the interference area as the frame is tilted.
NHTSA assumed by this comment that a design solution had been found to address the problem of the guard hitting the ground. Therefore, NHTSA believed it was only necessary to respond to NSWMA that guards were not required on the container, only the trailer that carries it.
We note that your current design already is nearly compliant with the configuration aspects of the rule. The drawing you sent us shows that the guard is mounted to the back of the traveling rear axle and extends rearward from the axle. One drawing shows the rear surface of the guard's horizontal member within two inches of the required zone. Perhaps extending the mounting struts rearward another two inches would produce a compliant guard. Alternatively, you could contact NSWMA to explore the possibility of using the retractable guard design that it discussed.
If you believe your trailers should be excluded from Standard No. 224, you may submit a petition for rulemaking (see 49 CFR Part 552, which I have enclosed for your convenience) requesting that NHTSA amend the standard. 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.
Acting Chief Counsel