Interpretation ID: 16959-1.pja
Mr. Kenneth Mannen
Hesse, Inc.
6700 Saint John Avenue
Kansas City, MO 64123
Dear Mr. Mannen:
This responds to your facsimile requesting an interpretation of whether the beverage delivery trailers your company manufactures are excluded from the National Highway Traffic Safety Administration's (NHTSA's) rear impact protection (underride guard) regulations. As explained below, two of these trailer designs are excluded, but one design is not. An underride guard complying with our regulations would have to be supplied for that one design.
From the drawings you sent, it appears that all three types of beverage delivery trailers are segmented, with 40-52 inch wide doors on the sides that slide up and down, providing access to the stacked beverages. They differ mainly at the rear. Thank you for clarifying certain aspects of your trailer construction during a June 11, 1998 telephone conversation with Paul Atelsek of my staff. The different trailer designs are addressed separately, below.
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, special purpose vehicles, and low chassis vehicles.
Single Axle Beverage Delivery Trailer
The single axle trailer has the rearmost surface of its rear wheel currently located 12 to 13 inches forward of the rear of the rearmost point on the trailer bumper. You believe that this design is excluded if you assure that the rear wheel is 12 inches or less forward of the bumper by reducing the depth of the rear bumper or by moving the axle back. However you ask if it is necessary to alter your design to comply. Because the distance between the front of the bumper assembly and the rear tire is only 5 inches, you reason that the bumper could move forward only that distance before contacting the rear wheel and stopping.
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." One relevant issue is whether the rear wheels are permanently fixed. The axles on your trailer do appear to be fixed, because the beverage bay located a few inches in front of the trailer cannot be moved. Another question is whether the rear surface of the rear wheels is within 305 mm (12 inches) of the trailer rear extremity. In your drawing, the rear wheels are within 12 inches of the rear of the bumper, so we assume these are excluded as wheels-back vehicles. However, your letter mentions that some of your trailers have rear wheels more than 12 inches forward of the trailer rear extremity ("distance from the rear of the tire to the back of the bumper of between 12 & 13 inches"). These vehicles would not be excluded as wheels-back, and a compliant guard would have to be provided.
The fact that the bumper could move only 5 inches forward during a crash does not change this analysis. While it is true, in the event of a crash, your trailers have the bumper mounting assembly between the colliding vehicle and the rear tires, the language of the standard does not create an exception for this situation. The exclusions in Standard No. 224 are generally designed for trailers for which guards are either unnecessary or impractical. Most wheels-back vehicles do not have the full-width, low bumper-type assembly that you provide. As you observe in your letter, you could relocate the axle rearward slightly, or decrease slightly the depth of the bumper and these vehicles would then be considered wheels-back. Another option is to certify your existing bumper, which appears to meet the configuration requirements of Standard Nos. 223 and 224, as a compliant guard, after assuring yourself that it also meets the other requirements of those standards.
Tandem axle beverage delivery trailer
This trailer has a beverage storage bay behind the rear tandems. The rear bumper on this trailer is mounted to the back of the rear storage bay at a height of 15 to 17 inches above the ground. There is a horizontal structural member made of extruded aluminum 2.5 by 6.5 inches in thickness running longitudinally on each side of the trailer at the bottom of the rear storage bay. There is also a horizontal structural crossmember of the same stock that connects, across the back of the trailer, the rear of these longitudinal structural members. This transverse structural member is supported in the center by a cross member extending diagonally down and to the rear, between the main frame rails of the trailer and the rear bumper/bulkhead. It is also supported by gussets attached to the main frame rails. The bottom of this transverse structural member is also 15 to 17 inches above the ground. You believe that this design is excluded because it meets the definition of a low chassis vehicle.
Low chassis vehicles are defined in S4 of Standard No. 224 as "a trailer or semitrailer having a chassis that extends behind the rearmost point of the rearmost tires and a lower rear surface that meets the configuration requirements of S5.1.1 through 5.1.3 of this section." In other words, the chassis itself must satisfy the configuration requirements applicable to a guard when the vehicle is outfitted for transit. The only part of your trailer that may meet these configuration requirements is the transverse structural member under the floor of the rear storage bay. Therefore, the question becomes whether this structural member is considered to be part of the "chassis" of the vehicle. Chassis is defined in S4 as "the load supporting frame structure of a motor vehicle." There are two elements to this definition that must be satisfied: "load supporting" and "frame structure."
To be considered "load supporting," the frame structure has to support load when the trailer is performing its function. Generally, this means that the structure would have to contribute to supporting the cargo load when the trailer is in transit.
To be considered part of the frame structure, a structural member must be either an integral part of the overall frame structure, or be connected with other frame structural members in a way that is necessary to the structural integrity of the trailer. One factor the agency considers in deciding whether a structural member is part of the frame is its size and strength. Frame structural components often are the major structures defining the shape of the trailer. Although frame structure is not limited to the largest frame components (i.e., the frame rails for most trailers), generally frame components are substantial and have strength similar to other frame components. Moveable components may "lock" into the frame structure sufficiently that they are integral with other frame members-in this situation NHTSA may consider the combined components to be one frame unit. However, the agency also looks at the purpose and function of the structural member in supporting the trailer and its load.
Applying these principles to the transverse structural member at the bottom of your rear storage bay, we conclude that it is part of the chassis. The member underlies the rear storage bay and supports the beverages in that bay, so it is considered load supporting. It is also frame structure. The member is similar in size, and presumably in strength, with the other frame members. The member conforms with and helps to define the outline of the trailer. It is connected to the other frame members at least as strongly as the other storage bays, and likely more strongly, considering the diagonal member and the gussets. Therefore, we conclude that the member is part of the chassis, and the trailer is a low chassis vehicle, excluded from the underride guard requirements.
Tandem axle convertible beverage delivery trailer
This trailer is similar to the tandem axle trailer, with one major difference being that the rear bay loads from the rear instead of from the side. Another difference is that the rear compartment also does not extend downward as far on this design as it does on the tandem axle trailer. The bottom of the rear compartment is at the level of the frame rails, a few feet above the ground, instead of extending down to the 15 to 17 inch level. There are vertical structural members made of 6 inch channel in the rear corners of the trailer, forming the rear outside edges of the rear compartment. These channel members, as well as two vertical supports of rectangular tubing located farther inboard, extend downward below the bottom of the rear compartment, to within 14 to 20 inches of the ground. All of these vertical structural members are connected at the bottom across the back of the trailer by a transverse horizontal member composed of 5 inch high by 2.5 inch deep extruded aluminum tubing. This tubing resembles the horizontal member of a conventional underride guard. You state that you are not sure if this design is excluded.
Applying the same analysis as we applied to the tandem axle trailer, we conclude that this trailer is not a low chassis vehicle. The only part of the vehicle that meets the configuration requirements of S5.1.1 through S5.1.3 is the transverse horizontal member, so that would have to be considered to be part of the chassis for the vehicle to be excluded. This member hangs down from the rear of the trailer and forms no part of the rear compartment. Therefore, it fails the load supporting aspect of the definition. Consequently, it is not part of the chassis and the tandem convertible trailer is not excluded as a low chassis vehicle.
You asked if the addition of a "rail lift gate" to the rear of the convertible trailer would affect the compliance status of this trailer design. We assume you are asking this because you think the liftgate might result in the vehicle meeting the definition of an excluded "special purpose vehicle." 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 liftgate meets the agency's definition of work performing equipment. However, it is our understanding that most rail-type liftgates stow high on the vehicle's rear end and move entirely rearward of the rear extremity. If this is the case, the liftgate would not occupy the area designated for the guard, at least not during transit. Therefore, even if equipped with a rail-type liftgate, the vehicle would not meet the definition of a special purpose vehicle. Because no other exclusions apply, this trailer would need to be equipped with a compliant rear underride guard.
We cannot provide a specific opinion on how your trailer might be redesigned to accommodate a guard. We note, however, that the transverse piece of rectangular tubing already appears to meet the configurational requirements for an underride guard. If it does not currently meet the strength and energy absorption requirements, you might be able to reinforce or otherwise modify the vertical supports sufficiently so that it would pass these requirements. If you can do this, the transverse horizontal member itself could be labeled and certified as a guard under Standard No. 223, Rear impact guards. Perhaps this solution would work for you. However, we emphasize that 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 that 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
ref:224
d.8/24/98
1. Note that this definition, as quoted, reflects an amendment made in response to petitions for reconsideration of the final rule. An unnecessary reference to pipe equipment containing hazardous materials was eliminated. See 63 F.R. 3654 (January 26, 1998).