NHTSA Interpretation File Search
Overview
NHTSA's Chief Counsel interprets the statutes that the agency administers and the standards and regulations that it issues. Members of the public may submit requests for interpretation, and the Chief Counsel will respond with a letter of interpretation. These interpretation letters look at the particular facts presented in the question and explain the agency’s opinion on how the law applies given those facts. These letters of interpretation are guidance documents. They do not have the force and effect of law and are not meant to bind the public in any way. They are intended only to provide information to the public regarding existing requirements under the law or agency policies.
Understanding NHTSA’s Online Interpretation Files
NHTSA makes its letters of interpretation available to the public on this webpage.
An interpretation letter represents the opinion of the Chief Counsel based on the facts of individual cases at the time the letter was written. While these letters may be helpful in determining how the agency might answer a question that another person has if that question is similar to a previously considered question, do not assume that a prior interpretation will necessarily apply to your situation.
- Your facts may be sufficiently different from those presented in prior interpretations, such that the agency's answer to you might be different from the answer in the prior interpretation letter;
- Your situation may be completely new to the agency and not addressed in an existing interpretation letter;
- The agency's safety standards or regulations may have changed since the prior interpretation letter was written so that the agency's prior interpretation no longer applies; or
- Some combination of the above, or other, factors.
Searching NHTSA’s Online Interpretation Files
Before beginning a search, it’s important to understand how this online search works. Below we provide some examples of searches you can run. In some cases, the search results may include words similar to what you searched because it utilizes a fuzzy search algorithm.
Single word search
Example: car
Result: Any document containing that word.
Multiple word search
Example: car seat requirements
Result: Any document containing any of these words.
Connector word search
Example: car AND seat AND requirements
Result: Any document containing all of these words.
Note: Search operators such as AND or OR must be in all capital letters.
Phrase in double quotes
Example: "headlamp function"
Result: Any document with that phrase.
Conjunctive search
Example: functionally AND minima
Result: Any document with both of those words.
Wildcard
Example: headl*
Result: Any document with a word beginning with those letters (e.g., headlamp, headlight, headlamps).
Example: no*compl*
Result: Any document beginning with the letters “no” followed by the letters “compl” (e.g., noncompliance, non-complying).
Not
Example: headlamp NOT crash
Result: Any document containing the word “headlamp” and not the word “crash.”
Complex searches
You can combine search operators to write more targeted searches.
Note: The database does not currently support phrase searches with wildcards (e.g., “make* inoperative”).
Example: Headl* AND (supplement* OR auxiliary OR impair*)
Result: Any document containing words that are variants of “headlamp” (headlamp, headlights, etc.) and also containing a variant of “supplement” (supplement, supplemental, etc.) or “impair” (impair, impairment, etc.) or the word “auxiliary.”
Search Tool
NHTSA's Interpretation Files Search
| Interpretations | Date |
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ID: nht93-1.10OpenDATE: January 14, 1993 FROM: Bob Dittert -- Trooper, Texas Department of Public Safety, Safety Education Service TO: Chief Counsel -- NHTSA COPYEE: Janet Monteros -- Office of the Attorney General, General Litigation Section TITLE: None ATTACHMT: Attached to letter dated 5-5-93 from John Womack to Bob Dittert (A41; Std. 205; VSA 103(d)) TEXT: It would be appreciated if your agency would make clear the authority of the CFR's concerning automotive equipment standards for new vehicles and after- market equipment. 1. Are the CFR's law and enforceable only by federal agents? 2. Are the Federal Motor Vehicle Safety Standards law and only enforceable on new manufactured vehicles? 3. Are states allowed to enact legislation that allows less stringent standards than the CFR's? 4. Concerning the installation of non-complying automotive equipment, i.e., sun screening, taillamp 'black out' lenses, neon license plate lamps, etc., is this allowed by the owner but prohibited installation by a commercial entity? I am of the understanding that the CFR 48, Part 571.105 requires light transmission of 70% minimum (words illegible) is this correct? If this is correct and Texas law, VCS S701(illegible) Art. XII, Sec. 184(C), allows light transmission of only 35% (words illegible) action of Federal law? (Words illegible) Sec. 108 stated that if a Federal standard for any item of automotive equipment exists that standard will take precedence over any state standard and this section also empowers the Department (Texas Department of Public Safety) to control the sale and use of automotive equipment. If the state statutes are in error can that be remedied by the Federal Government? If so, how? It doesn't seem realistic that every state could have different standards for automotive equipment, either new manufactured vehicles or after-market! Your answers to these questions are awaited in ernest. |
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ID: 1983-1.2OpenTYPE: INTERPRETATION-NHTSA DATE: 01/07/83 FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA TO: Stanley Electric Co. Ltd. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of November 23, 1982, to Mr. Elliott of this agency asking whether you may distinguish between U.S. and Japanese-manufactured lighting equipment subject to Federal Standard No. 108 by marking the lenses "U.S.A. DOT" and "JAPAN DOT", rspectively. As you know, the National Highway Traffic Safety Administration has not adopted the SAE standard on equipment marking, J759c. This means that the only marking subject to Standard No. 108 is that which certifies compliance to all applicable Federal motor vehicle safety standards, the DOT symbol. We believe that the intended proximity of the words "Japan DOT" in your Japanese-manufactured equipment might create the impression that Stanley was certifying compliance to the requirements of the Japanese Ministry of Transport, rather than to those of the U.S. Department of Transportation. Therefore, we suggest that you place the word "Japan" at the end of the line rather than adjacent to the "DOT" symbol. SINCERELY, STANLEY ELECTRIC CO., LTD. November 23, 1982 Att.: Marx Elliott Office of Rulemaking National Highway Traffic Safety Administration Dear Mr. Elliott, We, Stanley Electric Co., Ltd. corporated in Japan (hereafter reffered to as STANLEY-JPN) have estblished Stanley Electric U.S. Co., Inc. corporated in London, Ohio (hereafter reffered to as STANLEY-US) with 100 % investments, and we are in process of preparing to start producing, beginning with the lighting equipments for 1984 model vehicles. In the work we are proceeding, we are faced with a problem, the first case for us, which relates to the identification marking to be indicated on the lighting devices. So, we would like to ask you whether or not our view is right. Honda Motor Co., LTD. (Japan) will manufacture the same type of vehicles both in Japan and in U.S.A (HONDA OF AMERICA). Therefore, their lighting devices of the same design will be manufactured by STANLEY-JPN and by STANLEY-US, and supplied to the Honda plant in each area. Because these lighting devices are of the same design (STANLEY-JPN keeps the original drawings. And only STANLEY-JPN takes proceedings for their modifications.), we intend to indicate the same indentification making to the products made in Japan and made in U. S. A. However, in order to make a country of origin clear, it is our intention to add the marking "JAPAN" or U.S.A." to the identification marking, though it is not explained in Lighting Identification Code-SAE J759c. The following is an example: For products made in Japan : "STANLEY 043-6371 SAE AIST 80 JAPAN DOT" For products made in U.S.A.: "STANLEY 043-6371 SAE AIST 80 U.S.A. DOT" Please let us know whether or not the above view has no problem. Thanking you in advance, H. Miyazawa Director, Automotive Lighting Engineering Dept. |
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ID: 1652yOpen Mr. Leonard M. Perkins Dear Mr. Perkins: Secretary Burnley has asked me to respond to your letter of September 7, 1988, with respect to your lighting device. In essence, this is a center high-mounted stop lamp, with turn signal lamps adjacent to it. You believe that high-mounted turn signals "joined with the rear window brake light should have a dramatic effect on rear and side collisions", but you have been told that "this conception is at present illegal." Paragraph S4.4 of Federal Motor Vehicle Safety Standard No. l08 states that "no high-mounted stop lamp shall be combined with any other lamp or reflective device." We interpret this as prohibiting lamps or reflective devices that share a single lens or compartment with the center highmounted lamp. Your device shows lamps adjacent to the center highmounted lamp but not combined with it. Therefore, your device is not prohibited by that paragraph of the standard if you wish to market this device as original equipment. The next question to ask is whether it impairs the effectiveness of required lighting equipment (paragraph S4.1.3), principally the center stoplamp. For example, if the yellow turn signals were too bright or if the color of the turn signal were red, these lamps might "impair the effectiveness" of the center stoplamp. However, this is a determination to be made, in the first instance, by the manufacturer of the vehicle who must certify compliance with Standard No. l08. If you wish to sell your device in the aftermarket, it is acceptable under Federal law if its installation does not adversely affect the operation of motor vehicle equipment installed in accordance with a Federal motor vehicle safety standard so that the equipment would no longer comply with the standard. Assuming that the installation does not have this effect, the legality of installing or using such a device must then be determined according to the laws of any State in which a vehicle so equipped is registered or operated, and these auxiliary lamps must comply with any State requirements. We cannot advise you on State laws. One source of advice is the American Association of Motor Vehicle Administrators, 4600 Wilson Blvd., Arlington, Va. 22203. Sincerely,
Erika Z. Jones Chief Counsel ref:108 d:l/l8/89 |
1970 |
ID: nht89-3.24OpenTYPE: INTERPRETATION-NHTSA DATE: 10/31/89 FROM: STEPHEN P. WOOD -- NHTSA ACTING CHIEF COUNSEL TO: MARK F. HOLMES TITLE: NONE ATTACHMT: LETTER DATED 09/28/89 FROM MARK F. HOLMES TO STEVE WOOD -- NHTSA; OCC 3980; LETTER DATED 09/28/89 FROM MARK F. HOLMES TO STEVE WOOD -- NHTSA TEXT: Dear Mr. Holmes: This is in reply to your letter of September 28, 1989, with respect to two lighting devices known as the Strobalarm and the Spotlight Alarm. You are interested in selling these devices in the aftermarket, and have asked whether they would be in violatio n of any of the standards and regulations of this agency. These devices are "designed to be used only when a vehicle is parked or broken down." As we understand your letter and the materials you enclosed, both devices can be incorporated into existing alarm systems, to indicate when an attempted theft is in pro gress. The "locator" feature of the devices allows activation from a distance of 400 feet, enabling an approaching owner to easily identify his vehicle. With the use of a pink colored lens, the Strobalarm is intended to serve as an "emergency distress flare." You have enclosed two color renderings of these devices, titled "Interior/Strobe Alarm Light," and "Alarm Strobe Light Collision Avoidance Light." The Federal law and regulation that must be considered to answer your question are the National Traffic and Motor Vehicle Safety Act (Title 15, United States Code, Sections 1381 and following), and Federal Motor Vehicle Safety Standard No. 108 Lamps, Ref lective Devices and Associated Equipment (Title 49, Code of Federal Regulations, Section 571.108), and Standard No. 111 Rearview Mirrors (49 CFR 571.111). Under Section 1397(a)(2)(A) of the Act, a manufacturer, distributor, dealer, or motor vehicle repa ir business may not render inoperative, in whole or in part, any item of equipment installed in accordance with a Federal motor vehicle safety standard. You will note that this prohibition does not extend to the vehicle owner. Thus, the question to be addressed is whether the installation of either device by a manufacturer, distributor, dealer, or motor vehicle repair business would affect the performance of required safety equipment. The "Interior Strobe/Alarm Light" appears intended as a "dome" light, mounted centrally on the headliner above the passenger seats. In this position it has the potential to affect the field of view of the inside rear view
mirror required by Standard No. 111, as prescribed by paragraph S5.1.1 (copy enclosed). If the field of view is not met, an outside rearview mirror must be provided on the passenger side. You have not provided the dimensions of this device, and we are unable to advise you further. Other than this cautionary note, the "Interior Strobe/Alarm Light" does not appear affected by the laws and regulations of this agency. It would, however, be subject to state and local laws where it is sold and used. We a re unable to advise you on these, and suggest you contact the American Association of Motor Vehicle Administrators (AAMVA) for an opinion. Its address is 4600 Wilson Boulevard, Arlington, VA 22203. The "Alarm Strobe Light Collision Avoidance Light" raises another consideration. The collision avoidance portion of the lamp appears intended to serve as a center highmounted stop lamp. Under paragraph S5.4 of Standard No. 108, the center lamp may not b e combined with any other lamp or reflective device. Thus, removal of an original equipment center lamp and substitution of your device by a person other than the vehicle owner would be regarded as partially rendering inoperative the original safety equ ipment, even if your device complied with all other requirements for the center lamp. The center lamp has been required on all passenger cars manufactured on or after September 1, 1985. The restriction does not apply, of course, to installation on passenger cars manufactured before September 1, 1985, or other types of motor vehicles regardless of date of manufacture. Consideration must still be given, however, to continued compliance w ith Standard No. 111, and to whether any state specifications exist covering aftermarket center stop lamps. Again, the AAMVA may be able to help you. I hope that this information is useful to you. Sincerely, |
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ID: aiam4653OpenMr. Mark F. Holmes 2605-C Norris Ct. Philadelphia, PA 19121; Mr. Mark F. Holmes 2605-C Norris Ct. Philadelphia PA 19121; "Dear Mr. Holmes: This is in reply to your letter of September 28 1989, with respect to two lighting devices known as the Strobalarm and the Spotlight Alarm. You are interested in selling these devices in the aftermarket, and have asked whether they would be in violation of any of the standards and regulations of this agency. These devices are 'designed to be used only when a vehicle is parked or broken down.' As we understand your letter and the materials you enclosed, both devices can be incorporated into existing alarm systems, to indicate when an attempted theft is in progress. The 'locator' feature of the devices allows activation from a distance of 400 feet, enabling an approaching owner to easily identify his vehicle. With the use of a pink colored lens, the Strobalarm is intended to serve as an 'emergency distress flare.' You have enclosed two color renderings of these devices, titled 'Interior/Strobe Alarm Light,' and 'Alarm Strobe Light Collision Avoidance Light.' The Federal law and regulation that must be considered to answer your question are the National Traffic and Motor Vehicle Safety Act (Title 15, United States Code, Sections 138l and following), and Federal Motor Vehicle Safety Standard No. l08 Lamps, Reflective Devices and Associated Equipment (Title 49, Code of Federal Regulations, Section 571.108), and Standard No. lll Rearview Mirrors (49 CFR 571.111). Under Section 1397(a)(2)(A) of the Act, a manufacturer, distributor, dealer, or motor vehicle repair business may not render inoperative, in whole or in part, any item of equipment installed in accordance with a Federal motor vehicle safety standard. You will note that this prohibition does not extend to the vehicle owner. Thus, the question to be addressed is whether the installation of either device by a manufacturer, distributor, dealer, or motor vehicle repair business would affect the performance of required safety equipment. The 'Interior Strobe/Alarm Light' appears intended as a 'dome' light, mounted centrally on the headliner above the passenger seats. In this position it has the potential to affect the field of view of the inside rear view mirror required by Standard No. lll, as prescribed by paragraph S5.1.1 (copy enclosed). If the field of view is not met, an outside rearview mirror must be provided on the passenger side. You have not provided the dimensions of this device, and we are unable to advise you further. Other than this cautionary note, the 'Interior Strobe/Alarm Light' does not appear affected by the laws and regulations of this agency. It would, however, be subject to state and local laws where it is sold and used. We are unable to advise you on these, and suggest you contact the American Association of Motor Vehicle Administrators (AAMVA) for an opinion. Its address is 4600 Wilson Boulevard, Arlington, VA 22203. The 'Alarm Strobe Light Collision Avoidance Light' raises another consideration. The collision avoidance portion of the lamp appears intended to serve as a center highmounted stop lamp. Under paragraph S5.4 of Standard No. l08, the center lamp may not be combined with any other lamp or reflective device. Thus, removal of an original equipment center lamp and substitution of your device by a person other than the vehicle owner would be regarded as partially rendering inoperative the original safety equipment, even if your device complied with all other requirements for the center lamp. The center lamp has been required on all passenger cars manufactured on or after September 1, l985. The restriction does not apply, of course, to installation on passenger cars manufactured before September 1, l985, or other types of motor vehicles regardless of date of manufacture. Consideration must still be given, however, to continued compliance with Standard No. lll, and to whether any state specifications exist covering aftermarket center stop lamps. Again, the AAMVA may be able to help you. I hope that this information is useful to you. Sincerely, Stephen P. Wood Acting Chief Counsel Enclosure /"; |
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ID: 2109yOpen Mr. Mark F. Holmes Dear Mr. Holmes: This is in reply to your letter of September 28, 1989, with respect to two lighting devices known as the Strobalarm and the Spotlight Alarm. You are interested in selling these devices in the aftermarket, and have asked whether they would be in violation of any of the standards and regulations of this agency. These devices are "designed to be used only when a vehicle is parked or broken down." As we understand your letter and the materials you enclosed, both devices can be incorporated into existing alarm systems, to indicate when an attempted theft is in progress. The "locator" feature of the devices allows activation from a distance of 400 feet, enabling an approaching owner to easily identify his vehicle. With the use of a pink colored lens, the Strobalarm is intended to serve as an "emergency distress flare." You have enclosed two color renderings of these devices, titled "Interior/Strobe Alarm Light," and "Alarm Strobe Light Collision Avoidance Light." The Federal law and regulation that must be considered to answer your question are the National Traffic and Motor Vehicle Safety Act (Title 15, United States Code, Sections 138l and following), and Federal Motor Vehicle Safety Standard No. l08 Lamps, Reflective Devices and Associated Equipment (Title 49, Code of Federal Regulations, Section 571.108), and Standard No. lll Rearview Mirrors (49 CFR 571.111). Under Section 1397(a)(2)(A) of the Act, a manufacturer, distributor, dealer, or motor vehicle repair business may not render inoperative, in whole or in part, any item of equipment installed in accordance with a Federal motor vehicle safety standard. You will note that this prohibition does not extend to the vehicle owner. Thus, the question to be addressed is whether the installation of either device by a manufacturer, distributor, dealer, or motor vehicle repair business would affect the performance of required safety equipment. The "Interior Strobe/Alarm Light" appears intended as a "dome" light, mounted centrally on the headliner above the passenger seats. In this position it has the potential to affect the field of view of the inside rear view mirror required by Standard No. lll, as prescribed by paragraph S5.1.1 (copy enclosed). If the field of view is not met, an outside rearview mirror must be provided on the passenger side. You have not provided the dimensions of this device, and we are unable to advise you further. Other than this cautionary note, the "Interior Strobe/Alarm Light" does not appear affected by the laws and regulations of this agency. It would, however, be subject to state and local laws where it is sold and used. We are unable to advise you on these, and suggest you contact the American Association of Motor Vehicle Administrators (AAMVA) for an opinion. Its address is 4600 Wilson Boulevard, Arlington, VA 22203. The "Alarm Strobe Light Collision Avoidance Light" raises another consideration. The collision avoidance portion of the lamp appears intended to serve as a center highmounted stop lamp. Under paragraph S5.4 of Standard No. l08, the center lamp may not be combined with any other lamp or reflective device. Thus, removal of an original equipment center lamp and substitution of your device by a person other than the vehicle owner would be regarded as partially rendering inoperative the original safety equipment, even if your device complied with all other requirements for the center lamp. The center lamp has been required on all passenger cars manufactured on or after September 1, l985. The restriction does not apply, of course, to installation on passenger cars manufactured before September 1, l985, or other types of motor vehicles regardless of date of manufacture. Consideration must still be given, however, to continued compliance with Standard No. lll, and to whether any state specifications exist covering aftermarket center stop lamps. Again, the AAMVA may be able to help you. I hope that this information is useful to you. Sincerely, Stephen P. Wood Acting Chief Counsel Enclosure / ref:VSA#l08#lll d:l0/3l/89 |
1970 |
ID: 10-000638_Bradley_trailer_tail2OpenMr. David H. Bradley Canadian Trucking Alliance Butterworth House 324 Somerset St. West, Suite 100 Ottawa, ON Canada K2P 0J9 Dear Mr. Bradley: This responds to your letter concerning an aerodynamic device manufactured by Advanced Transit Dynamics, Inc. (ATDynamics) called a boat tail or trailer tail that some of your member motor carriers would like to install on their van trailers to reduce the fuel consumption of their vehicles. (In this letter, we will refer to these aerodynamic devices generally as trailer tails and to the device manufactured by ATDynamics as the ATDynamics TrailerTail.) You state that use of trailer tail technology would help meet a California Air Resources Board regulation that requires all U.S. and Canadian 53-foot van trailers to achieve a 5 percent overall reduction in greenhouse gas emissions by 2016. Background In your letter, you ask for our acceptance of an October 10, 2008 letter from the Director of the Federal Highway Administrations (FHWAs) Office of Freight Management and Operations to ATDynamics, a copy of which you enclosed. (October 10, 2008 letter from Anthony Furst to ATDynamics Andrew Smith.) In the letter, Mr. Furst discusses FHWA regulation 23 CFR 658.16, Exclusions from length and width determinations. Subsection (b) of 658.16 sets forth exclusions from either the measured length or width of commercial motor vehicles, as applicable, and lists aerodynamic devices in subpart (4). Mr. Furst states in the letter that FHWA regulation 23 CFR 658.16(b)(4) excludes an aerodynamic device from the measured length of a commercial motor vehicle provided: (1) the device is not capable of carrying cargo; (2) the device does not extend beyond 5 feet of the rear of the vehicle; (3) the device does not obscure tail lamps, turn signals, marker lamps, identification lamps, or safety devices such as hazardous material placards or conspicuity markings; and, (4) the device has neither the strength, rigidity nor mass to damage a vehicle, or injure a passenger in a vehicle that strikes a vehicle so equipped from the rear. Mr. Furst concludes that FHWA has determined that the ATDynamics TrailerTail meets the conditions of 23 CFR 658.16(b)(4). He states that FHWA-- acknowledges that ATDynamics Trailer Tail was tested by an independent laboratory, KARCO Engineering, and was found to be in compliance with all elements of 23 CFR 658.16(b) (4). Therefore, in accordance with Federal regulations, the ATDynamics Trailer Tail aerodynamic device should be excluded from the length measurements for commercial motor vehicles. KARCO Engineering determined that the ATDynamics Trailer Tail aerodynamic device Passed all of the conditions listed in the regulation, and FHWA accepts those results. Mr. Furst also states that FHWA shared the test results with staff from the National Highway Traffic Safety Administration (NHTSA) for review. Mr. Furst states: NHTSA identified a conspicuity marking issue[and] ATDynamics has taken care of the issue in the manner NHTSA recommended. With that background in mind, in your letter to us you ask for clarification from NHTSA with regard to the process for defining compliance with 23 CFR 658.16(b)(4) on aerodynamic devices. In other words, as we understand your letter, you ask us to confirm that use of the ATDynamics TrailerTail would not violate Federal laws administered by NHTSA. We note that Transport Canada has also contacted us for our views on trailer tails. NHTSAs Framework It would be helpful in answering your question to begin with a discussion of NHTSAs authority under the National Traffic and Motor Vehicle Safety Act (49 U.S.C. Chapter 301, Vehicle Safety Act). NHTSA is authorized under the Vehicle Safety Act to issue Federal motor vehicle safety standards (FMVSSs) applying to the manufacture and sale of new motor vehicles and items of motor vehicle equipment. Manufacturers are required to self-certify that their products conform to all applicable FMVSSs in effect on the date of manufacture. This agency does not provide approvals of new motor vehicles or of modifications of used vehicles. NHTSA has exercised its rulemaking authority to establish a number of standards that apply to new trailers. Those standards include FMVSS No. 108, Lamps, reflective devices, and associated equipment (49 CFR 571.108), which requires trailers to have specified systems to provide adequate illumination of the roadway and to improve the conspicuity of the vehicles. Another standard applying to trailers is FMVSS No. 224, Rear impact protection (49 CFR 571.224). Standard No. 224 requires trailers to have rear impact guards to reduce the harm to occupants of light duty vehicles impacting the rear of the trailer. Each new trailer with a trailer tail sold in the U.S. must be certified by its manufacturer as complying with all applicable standards, including FMVSS No. 108 and No. 224. After the first purchase of a vehicle for purposes other than resale, the Vehicle Safety Act limits modifications that may be made to the vehicle by commercial entities. 49 U.S.C. 30122 states: A manufacturer, distributor, dealer, or motor vehicle repair business may not knowingly make inoperative any part of a device or element of design installed on or in a motor vehicle or motor vehicle equipment in compliance with an applicable motor vehicle safety standard prescribed under this chapter. In the case of the motor carriers mentioned in your letter, this provision would prohibit a commercial business from installing a trailer tail on a motor carriers new or used vehicle in a manner that would negatively affect the vehicle's compliance with FMVSS No. 108 or No. 224 or any other safety standard.[1], [2] Discussion The question posed by your letter is whether installing the ATDynamics TrailerTail on a new or used vehicle would be permitted under NHTSAs regulations. Unfortunately, we cannot provide a sweeping answer that covers all installations of the ATDynamics TrailerTail. NHTSA assesses the compliance of new vehicles and administers the make inoperative provision of the Vehicle Safety Act concerning new or used vehicles independently from other agencies. We do not approve motor vehicles or processes undertaken by manufacturers. A possible violation of the FMVSSs or the make inoperative provision is evaluated by NHTSA according to the facts of each particular case. Thus, NHTSA would evaluate, among other matters, the design and construction of a particular ATDynamics TrailerTail, the manner in which the trailer tail was attached, and whether the trailer tail impaired the effectiveness of the trailers lamps and other devices installed pursuant to FMVSS No. 108. We cannot prospectively and categorically affirm that all future uses of the ATDynamics device would be acceptable to this agency. However, we recognize and appreciate the effort that has been made seeking the agencies input in exploring possible safety issues related to the ATDynamics TrailerTail. In view of those efforts, we make the following observations based on the KARCO Engineering (KE) test. KE conducted a 35 mile per hour rear offsest crash test for ATDynamics. ATDynamics installed a TrailerTail on a 1991 Pine Trailer. The test vehicle and set-up was prepared by KE. The impacting vehicle was a 1994 Ford Econoline 350 Van. Two Hybrid III 50th percentile adult male test dummies equipped with head triaxial accelerometers to measure head injury accelerations were placed in the driver and right-front passenger seating positions. KEs report on the test states (Laboratory Test Report, Rear-Mounted Aerodynamic Device, TrailerTail mounted to a 1991 Pine Trailer, Prepared for Advanced Transit Dynamics, Inc., July 22, 2008, KARCO Engineering): (a) Inspection of pre- and post-test photographic data showed no appreciable deformation of any structural component of the impacting vehicle attributable to the trailer tail (not including glass, plastic lenses, or trim components); (b) The head injury criterion of neither test dummy exceeded a value of 1,000 as a result of direct contact with the trailer tail; and (c) There was no evidence from either post-test inspection of the transfer of chalk applied to the test dummies or from still or high speed photography that the trailer tail or any resilient component of the impacting vehicle made contact with any portion of the test dummies as a result of contact of the impacting vehicle with the trailer tail. In addition, the report indicates that the open geometry of the ATDynamics TrailerTail does not allow it to carry cargo, and that the vehicles lamps and conspicuity markings would meet FMVSS No. 108. The test data from the KE test indicate that the ATDynamics TrailerTail did not negate the vehicles ability to meet FMVSS No. 224[3] and that the rear impact guard on the vehicle was not made inoperative by the ATDynamic TrailerTail. Thus, there is no basis for NHTSA to conclude at this time that installation of the ATDynamics TrailerTail is prohibited. Please note that NHTSA is interested in Transport Canadas on-going work evaluating the safety and performance of trailer tails. NHTSA will evaluate the outcome of Canadas research to see if we should undertake further work on trailer tails. If you have any other questions, please contact Deirdre Fujita of my staff at this address or by phone at (202) 366-2992. Sincerely, O. Kevin Vincent Chief Counsel 1/24/2011 [1] The make inoperative provision applies to a manufacturer, distributor, dealer, or repair business installing a trailer tail, and not to a vehicle owner that modifies its own vehicle. However, States have the authority to regulate the operation of vehicles in their jurisdictions, and may have restrictions on the type of modifications owners may make. [2] The Vehicle Safety Act also requires manufacturers of motor vehicles and motor vehicle equipment to ensure that their products are free of safety-related defects. A trailer tail would be considered motor vehicle equipment under the Vehicle Safety Act. [3] That is, it appears that the trailer tail would qualify as a nonstructural protrusion under FMVSS No. 224. See S4, definition of rear extremity. |
Request an Interpretation
You may email your request to Interpretations.NHTSA@dot.gov or send your request in hard copy to:
The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590
If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.
Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.