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 |
|---|---|
ID: GF001071OpenMr. David Regan Dear Mr. Regan: This responds to your February 10, 2004, letter and phone conversation with George Feygin of my staff. You ask whether snow melting machines manufactured by your company would be classified as "motor vehicles." You manufacture three different machines with the primary function of melting large quantities of snow. In order to move from location to location, these machines are equipped with wheels and function much like a trailer. As explained below, based on the information you provided us, we would not consider these machines to be motor vehicles for the purposes of our regulations. Title 49 U.S.C Chapter 301 authorizes the National Highway Traffic Safety Administration (NHTSA) to prescribe Federal motor vehicle safety standards (FMVSSs) applicable to new motor vehicles and new items of motor vehicle equipment. Section 30102(a)(6) defines "motor vehicle" as:
NHTSA has issued several interpretations of this language. We have stated that vehicles equipped with tracks, agricultural equipment, and other vehicles incapable of highway travel are not motor vehicles. We have also determined that certain vehicles designed and sold solely for off-road use (e.g., airport runway vehicles and underground mining vehicles) are not motor vehicles, even if they may be operationally capable of highway travel. Finally, we have concluded that items of mobile construction equipment that use the highways only to move between job sites and that typically spend extended periods of time at a single site are not motor vehicles. However, we do consider vehicles that use the public roads on a necessary and recurring basis to be motor vehicles. In the present case, your letter states that your snow melting machines are designed primarily for use by airports and other large facilities, such as parking garages. While these machines are capable of highways travel, you state that in all likelihood such travel will be limited to reaching permanent or semi-permanent job sites (i.e specific locations where large snow piles are continuously accumulated). Based on this information, it appears that these machines are akin to airport runway vehicles or items of mobile construction equipment that do not travel on highways on a recurring basis. Accordingly, we find that the snow melting machines described in your letter are not "motor vehicles." Because these machines are not motor vehicles, they are not subject to our regulations and requirements, including the requirement to meet all applicable FMVSSs. We note that our finding is limited specifically to the equipment described in your letter, and is largely based on your representation of its intended use. In your correspondence, you state that some snow melting machines may be sold to large cities, but you do not elaborate further. We presume that snow melting machines purchased by large cities would also remain mostly at some single location designated for snow melting activities. However, we wish to caution that our finding does not apply to snow melting equipment that is intended to be used extensively on public roads on a recurring basis. I hope you find this information helpful. If you have any other questions please contact Mr. George Feygin at (202) 366-2992. Sincerely, Jacqueline Glassman ref:571 |
2004 |
ID: GF001563aOpenMr. Ian James Dear Mr. James: This responds to your January 5, 2004, letter, as well as e-mail and phone communications with George Feygin of my staff, concerning the National Highway Traffic Safety Administrations (NHTSAs) Federal motor vehicle theft prevention standard, 49 CFR Part 541 (Part 541). You ask if glazing is considered a part of the door for the purposes of the standards parts marking requirements. You also ask whether parts marking can be applied to vehicles at the point of export, as opposed to the point of manufacture. We note that you originally wrote intending to comment on our June 26, 2002, notice of proposed rulemaking (NPRM) that proposed revisions to the theft prevention standard (67 FR 43075). As Mr. Feygin informed you, the comment period for the NPRM closed on August 26, 2002. Nonetheless, because the issues you raise are primarily requests for interpretation of the standard, we can address them in this letter. By way of background, the purpose of Part 541 is to reduce the incidence of motor vehicle thefts by facilitating the tracing and recovery of parts from stolen vehicles. The standard requires identifying numbers or symbols (usually Vehicle Identification Numbers, see 49 CFR Part 565) to be placed on major parts of certain passenger motor vehicles. 49 CFR 541.5 lists 18 "major parts" subject to the parts marking requirements. Front and rear doors are included in this list. With respect to your first question, the agency does not consider window glazing that is mounted in and framed by a metal or fiberglass door structure to be a part of the "door" for the purposes of the parts marking requirements. Instead, under Part 541, the "door" is limited to the actual door structure. Glazing is designed and manufactured from a combination of glass and plastic, materials that are significantly different from metal and fiberglass normally used in manufacturing the "major parts" listed in 541.5. In inventory lists, manufacturers typically designate window glazing as a separate part from the metal doorframe. Glazing is also considerably more fragile than the major parts in 541.5, which makes it vulnerable to damage in a collision, and can be replaced relatively easily in a door. For these reasons, we do not consider marking the window glazing to meet 541.5s requirement to permanently mark the vehicles doors. With respect to your second question, Part 541 does not require that parts marking be applied at the point of manufacture. However, a vehicle certified by the manufacturer to meet U.S. safety, bumper, and theft prevention standards must be marked prior to the delivery to dealer or distributor for the certification to be valid (49 U.S.C. 30115). Thus, the standard does not prohibit application of parts marking at the point of export so long as it is done prior to the delivery to distributor or dealer. I hope you find this information helpful. If you have any other questions, please contact Mr. Feygin at this address or by phone at (202) 366-2992. Sincerely, Jacqueline Glassman ref:541 |
2004 |
ID: GF001689OpenMr. Kenneth Reed Dear Mr. Reed: This responds to your letter asking about S4.2.2(a) of Standard No. 114, Theft Protection, in connection with Jaguars "pass key technology." The issues raised by your letter are addressed below. By way of background, the National Highway Traffic Safety Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under 49 U.S.C. Chapter 301, manufacturers are required to certify that their vehicles and equipment meet applicable requirements. The following represents our opinion based on the facts you provided in your letter. Under S4.2.1 of Standard No. 114, the key-locking system in vehicles that have an automatic transmission with a "park" position, when tested under specified procedures, must generally prevent removal of the key unless the transmission or transmission shift lever is locked in "park" or becomes locked in "park" as the direct result of removing the key. S4.2.2(a) states (in relevant part) that notwithstanding S4.2.1, provided that steering is prevented upon the key's removal, each vehicle specified therein may permit key removal when electrical failure of the system (including battery discharge) occurs. You asked how S4.2.2(a) applies to key-locking systems using "pass key technology," i.e., systems using electronically coded cards or other means to enter an electronic key code into the locking system. In past interpretation letters, we have stated that the electronic code itself can be considered the key. You noted that in situations of sudden and complete loss of electrical power, the electronic key code could be immediately erased from the vehicles volatile memory, before a vehicle could be stopped. In considering your question, we believe it is helpful to note the history of the provision at issue. On January 17, 1992, we published in the Federal Register (57 FR 2039) a notice responding to petitions for reconsideration of amendments to Standard No. 114. Honda and Toyota, asking about key-locking systems using conventional keys, asked that the standard make it clear that key removal was permitted in the circumstance of electrical failure when the vehicle's transmission was not in park.
As explained in that notice, however, the agency decided to resolve the issue raised by Honda and Toyota by making it clear in the text of the standard that key removal is permitted in the circumstance of electrical failure when the vehicle's transmission is not in park. To implement this decision, the agency adopted the language of S4.2.2(a) discussed earlier; i.e., specifying that "(n)otwithstanding S4.2.1, provided that steering is prevented upon the key's removal, each vehicle specified therein may permit key removal when electrical failure of the system (including battery discharge) occurs . . . ." In considering the issues raised by your letter, it is our interpretation that the narrow provisions related to electrical failure do not apply to pass key technology where electronically coded cards or other means are used to enter an electronic key code into the locking system. These provisions were specifically crafted in the context of addressing whether (and under what circumstances) traditional keys should be permitted to be removed after battery discharge occurs, whereas, in the case of "pass key technology," electrical failure can automatically result in the immediate removal of the electronic key code. Moreover, the clause provided that steering is prevented upon the key's removal would not be appropriate in situations where sudden and complete loss of electrical power could result in immediate erasure of the electronic key code before a vehicle could be stopped, since paragraph S4.3 requires that steering be maintained in that situation. I hope this information is helpful. If you need further assistance, please contact George Feygin of my staff at this address or at (202) 366-2992. Sincerely, Jacqueline Glassman Enclosure |
2003 |
ID: GF001832OpenMr. E. Paul Daniels Dear Mr. Daniels: This responds to your letter dated January 26, 2005, asking whether S6.4 of Federal Motor Vehicle Safety Standard (FMVSS) No. 119 permits a motorcycle tire treadwear indicator height of greater that 0.8 mm.You asked about the possibility of raising it by as much as 0.6 mm, i.e., to 1.4 mm on new molds. By way of background, the National Highway Traffic Safety Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under 49 U.S.C. Chapter 301, manufacturers are required to certify that their vehicles and equipment meet applicable requirements. The Federal standard applicable to your question is FMVSS No. 119, New pneumatic tires for vehicles other than passenger cars.The relevant portion of that standard reads as follows:
The treadwear indicator requirement in S6.4 sets forth a specific standardized treadwear indicator height.A higher treadwear indicator is not permitted.We note that if the treadwear indicator height were raised to 1.4 mm, consumers would not be able to visually determine when the tire wore to a depth of 0.8 mm. We further note that in a document published on January 30, 1996, the agency denied a petition for rulemaking from Herzlich Consulting, Inc. to increase the treadwear indicator height requirement for passenger car tires (see 61 FR 2991).The agency explained that the treadwear indicator height limit was based on a long-standing industry practice, and that NHTSA adopted this industry practice. I hope you find this information helpful.If you need further assistance, please contact George Feygin of my staff at this address or at (202) 366-2992. Sincerely, Jacqueline Glassman ref:119 |
2005 |
ID: GF002121OpenMs. Alice Dee Rainville Dear Ms. Rainville: This responds to your e-mail of March 29, 2003, and subsequent communication with George Feygin of my staff, concerning your desire to see all newly manufactured vehicles be equipped with fire extinguishers. You also stated that you would like to see all state, county, municipal, and other emergency vehicles be required to have a fire extinguisher within easy access. You asked how one might go about trying to get such laws passed. Let me begin by saying that I am sorry to hear about your familys loss. Below please find our response to your inquiry. By way of background, the National Highway Traffic Safety Administration has the authority to establish Federal motor vehicle safety standards applicable to new motor vehicles and new items of motor vehicle equipment. We do not, however, regulate how vehicles are operated or maintained. This is a matter under state or local jurisdiction. Our data show that fires occur in 0.2 percent of vehicles in all crashes, but in 2.9 percent of fatal crashes. In addressing this safety problem, we are focusing our resources on upgrading the Federal standard on fuel system integrity, to limit the amount of fuel spillage during and after frontal, rear, and side impacts. We also have a number of regulatory activities underway to improve occupant protection in crashes. As we continue to conduct our activities, we will bear in mind the contribution that fire extinguishers can make. As to your desire to see state, county, municipal, and other emergency vehicles to be equipped with a fire extinguisher within easy access, you may wish to contact your local and state officials about this request. You might also wish to contact the National Association of State EMS Directors (http://www.nasemsd.org) and/or the American Association of Motor Vehicle Administrators (http://www.aamva.org). I hope you find this information helpful. If you have any questions, please contact George Feygin at (202) 366-2992 or by electronic mail at gfeygin@nhtsa.dot.gov. Sincerely, Jacqueline Glassman Enclosure |
2003 |
ID: GF002147OpenMr. Paul Fiore Director of Government and Business Relations Tire Industry Association 1532 Pointer Ridge Place Suite G Bowie, MD 20716-1883 Dear Mr. Fiore: This is in response to your March 22, 2006, letter concerning certain tire marking requirements in Federal Motor Vehicle Safety Standard (FMVSS) No. 119, New pneumatic tires for vehicles other than passenger cars. Specifically, you ask about load and inflation pressure markings on tires, and certain industry publications referenced by FMVSS No. 119. You also ask how these markings relate to Federal excise taxes. I begin by making two observations. First, the National Highway Traffic Safety Administration (NHTSA) does not collect or regulate collection of excise taxes. Therefore, we recommend that you contact Donald L. Korb, Chief Counsel of the Internal Revenue Service, with questions concerning Federal excise taxes. Second, George Feygin of my staff has previously provided you with a copy of our September 7, 2005, letter to Mark Jagow explaining that truck tires rated for dual load applications, including those produced solely for tandem use, must also be labeled with the maximum single load rating in addition to the dual load rating. Another copy of that letter is enclosed. FMVSS No. 119 establishes performance and marking requirements for tires on certain types of vehicles and references several industry publications containing tire size and capacity information. The publications are listed in S5.1(b) of FMVSS No. 119. You ask if load carrying capacity marking of tires that are featured in these publications must match the published load carrying capacity. S6.5 of FMVSS No. 119 requires, among other things, that truck tires be marked on each sidewall with the maximum load rating and corresponding inflation pressure for the particular tire (see paragraph (d)). S6.6 of FMVSS No. 119 further requires that if the maximum load rating for a particular tire size is shown in one or more of the publications described in S5.1(b) of FMVSS No. 119, each tire of that size designation shall have a maximum load rating that is not less than the published maximum load rating, or if there are differing published ratings for the same tire size designation, not less than the lowest published maximum load rating for the size designation. You also ask whether any new publications are being considered for recognition under S5.1(b) of FMVSS No. 119. On February 16, 2006, we received a petition from Mark Jagow asking the agency to amend S5.1(b) of FMVSS No. 119 by adding the China Marking Standards publication to the list specified in that section. The agency has not made a decision on how to proceed on the petition. The agency would issue a Notice of Proposed Rulemaking in order to afford an opportunity for comment before amending our regulations. Finally, you ask what tire markings are required for truck tire casings that were not originally manufactured for sale in the United States and are imported here for retreading and subsequent sale. We note, used tires for use on motor vehicles other than passenger cars which have less than 2/32 inch of tread depth and which are imported solely for retreading may be imported without certification. This is a narrow exception to the requirement that used tires have a DOT symbol on the sidewall to be legally imported. In determining that these tires are not motor vehicle equipment, NHTSA found persuasive that those tires cannot legally be used on the public highways, and require remanufacturing before they can be operated on the highways. There is no FMVSS applicable to retreaded tires for vehicles other than passenger cars. However, 49 CFR 574.5 does require each tire sold in the United States, including retreaded tires, to be labeled with Tire Identification Number (TIN) in order to facilitate a recall in the event of a defect. Under 574.5 (a) through (d), each TIN consists of (a) the manufacturers or retreaders identification code, (b) the tire size symbol, (c) optional tire type code, and (d) the date code; i.e. the week and year of manufacture. With respect to maximum load and maximum pressure, no regulation requires retreaded tires (for vehicles other than passenger cars) to show this information. I hope you find this information helpful. If you have further questions, you may contact Mr. George Feygin of my staff at (202) 366-2992. Sincerely,
Stephen P. Wood Acting Chief Counsel Enclosure ref:119 d.6/23/06 |
2006 |
ID: GF002230OpenMr. Greg Adams Dear Mr. Adams: This responds to your letter concerning tire safety. You stated that you have a 2002 truck which has a label stating that 10 ply tires should be used.You asked, "If a tire dealer installed 6 ply tires without owners knowledge, would they be the one responsible if something happened, or would the owner?" The National Highway Traffic Safety Administration (NHTSA) issues Federal Motor Vehicle Safety Standards applicable to new motor vehicles and motor vehicle equipment, including tires.Our tire standards specify tire dimensions; test requirements for strength, endurance, and high speed performance; labeling requirements; and tire load ratings.However, our regulations do not address the legal responsibilities of tire retailers vis--vis vehicle owners. We note that our regulations require that the maximum load rating be labeled on the tire sidewalls.The maximum load rating is the best guide for determining the load carrying capability of a tire.Therefore, the replacement tires for your vehicle should have had at least the equal maximum load rating as the tires originally on the vehicle. If you have further questions concerning our regulations, you may contact Mr. George Feygin of my staff at (202) 366-2992. Sincerely, Jacqueline Glassman ref:110 |
2005 |
ID: GF002300OpenMr. Paul Pridemore Dear Mr. Pridmore: This responds to your letter of March 14 and phone conversations with George Feygin of my staff, regarding your Model 7000 trailer. You asked us whether your trailer qualifies as a "special purpose vehicle" under Federal Motor Vehicle Safety Standard (FMVSS) No. 224, Rear Impact Protection. You also asked whether a "tilting rear guard," photographs of which you have enclosed, would satisfy the requirements of FMVSS No. 224, as well as FMVSS No. 223, Rear Impact Guards. I apologize for the delay in responding. The issues raised by your letter and phone conversations are addressed below. By way of background, the National Highway Traffic Safety Administration (NHTSA) administers Federal requirements for the manufacture and sale of new motor vehicles and certain items of motor vehicle equipment. NHTSA issues FMVSS applicable to new vehicles and equipment. Chapter 301 of Title 49 of the United States Code, "Motor Vehicle Safety" (49 U.S.C. 30101 et seq.), establishes a certification process under which each manufacturer is responsible for certifying that its products meet all applicable FMVSS. In an attempt to reduce the frequency and severity of underride collisions, NHTSA issued FMVSS No. 224 (61 FR 2004, January 24, 1996). The standard requires that all new trailers and semitrailers with a gross vehicle weight rating of 10,000 lbs or more be equipped with an underride guard that meets the requirements of FMVSS No. 223. The standard currently excludes pole trailers, pulpwood trailers, wheels-back trailers, and "special purpose vehicles" because attachment of an underride guard to these specific vehicles is impracticable or unnecessary. A "Special Purpose Vehicle" is defined in S4 of FMVSS No. 224 as a trailer or a 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. Your "tilting rear guard," which acts as an approach ramp when the trailer is tilted down, is the only part of your trailer that, while the vehicle is in transit, resides in the area that could be occupied by a conventional the rear impact guard. Therefore, this "tilting rear guard" would have to be considered work-performing equipment for your tilt bed trailer to be excluded. Your vehicle does not meet the definition of a special purpose vehicle. There is no definition of "work-performing equipment" in Standard No. 224. However, the Agency has historically interpreted 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. Approach ramps do not perform work in this sense because they merely form a ramp between the ground and the vehicle or equipment driving onto the tilt bed. Therefore, a "tilting rear guard" that acts as an approach ramp is not work-performing equipment, and your trailer does not meet the definition of a special purpose vehicle. In regard to your second question, we note that the static dimensions of your "tilting rear guard" (as described in your letter and accompanying photographs) appear to satisfy the requirements of FMVSS Nos. 223 & 224. Specifically, the guard appears to extend to within 100 mm of the side extremities of the trailer, thus satisfying the width requirement of S5.1.1; the bottom edge of the guard is said to be within 382 mm of the ground, thus satisfying height requirements of S5.1.2; and the guard appears to be on the very edge of the trailer, thus satisfying rear surface requirements of S5.1.3. However, FMVSS No. 223 contains guard strength and energy absorption requirements found in S5.2.1 and S5.2.2 respectively. You have provided no information as to whether the "tilting rear guard" is able to meet the performance requirements of S5.2.1 and S5.2.2. Accordingly, we are not in position to determine whether the "tilting rear guard" is in compliance with FMVSS Nos. 223 & 224. I hope this information is helpful. If you need further assistance, please contact George Feygin of my staff at this address or at (202) 366-2992. Sincerely, Jacqueline Glassman Enclosure |
2003 |
ID: GF002470OpenTed Gaston, Director of Maintenance Dear Mr. Gaston: This responds to your recent e-mail asking whether Federal Motor Vehicle Safety Standard (FMVSS) No. 108,Lamps, Reflective Devices and Associated Equipment, permits a hazard warning flasher system that actuates automatically each time a transit bus stops to pick up and discharge passengers. Our answer is no. By way of background, the National Highway Traffic Safety Administration does not provide approvals of motor vehicles or motor vehicle equipment. Under 49 U.S.C. Chapter 301, manufacturers are required to certify that their vehicles and equipment meet applicable requirements. In your e-mail, you describe a hazard warning flasher system which would automatically actuate each time the following criteria are met: (1) the bus is in gear, (2) brakes are applied, (3) the bus speed is below 3 mph, and (4) the front door is opened. Table I of FMVSS No. 108 requires motor vehicles, including transit buses, to be equipped with hazard warning signal systems, as specified in SAE Recommended Practice J910, February 1966. Paragraph 1 of SAE J910 defines such system, in part, as "a driver controlled device which causes all turn signal lamps to flash simultaneously". We have previously interpreted "driver controlled" to mean that the hazard warning signal system must be activated and deactivated by the driver and not by automatic means (please see attached letters to Paul Michelotti, Eric Reed, and Mark Steele). Accordingly, the system being contemplated by Muncie Indiana Transit System would be prohibited by FMVSS No. 108. I hope you find this information helpful. If you need further assistance, please contact George Feygin of my staff at this address or at (202) 366-2992. Sincerely, Jacqueline Glassman ref:108 |
2005 |
ID: GF002551.3OpenMr. Robert M. Clarke Dear Mr. Clarke: This responds to your March 11, 2005, letter regarding installation of certain auxiliary lighting on heavy-duty trucks and truck tractors. Specifically, you ask about installing auxiliary lamps in the vicinity of the front identification and clearance lamps. You also ask about installing auxiliary lamps above or below the surface occupied by front identification and clearance lamps. The standard relevant to your question is Federal Motor Vehicle Safety Standard (FMVSS) No. 108, Lamps, reflective devices and associated equipment. For vehicles of 80 or more inches in overall width (such as the trucks and the truck tractors described in your letter), Table II of FMVSS No. 108 requires that 3 amber identification lamps (three-lamp cluster) be located as close as practicable to the top center of the vehicle or the cab, with lamps placed 6 to 12 inches apart. The function of this three-lamp cluster is to indicate the presence of a large vehicle on the roadway. Table II also, requires that two amber clearance lamps be located "to indicate the overall width of the vehicle . . . and as near the top thereof as practicable." Before addressing the auxiliary lamp configurations discussed in your letter, we note that S5.1.3 of FMVSS No. 108 prohibits installation of lamps that would impair the effectiveness of the required lighting, including the identification lamp cluster. The agency has long maintained that highway traffic safety is enhanced by the familiarity of drivers with established lighting schemes, which facilitates their ability to instantly recognize the meaning the lamps convey and respond accordingly. Therefore, the agency previously explained that auxiliary lamps must be located such that they would not interfere or be confused with the lamps required by our standards. For example, in a January 21, 2004, interpretation letter to a confidential party, the agency explained that auxiliary lamps must be located far enough away from the three-lamp cluster, so that they do not impair their effectiveness. In an October 18, 2002, letter to Mr. Weidman, we indicated that two auxiliary lamps located next to the three-lamp cluster would detract from the purpose of the cluster. With this background in mind, we turn to auxiliary lamp configurations described in your letter. You provided descriptions and illustrations showing several different lamp configurations and asked whether these configurations would be permitted under FMVSS No. 108. Specifically, you describe three configurations consisting of the three-lamp identification cluster, two clearance lamps, and one or more sets of auxiliary lamps located between the clearance lamps and the three-lamp cluster. You ask if all three configurations would comply with FMVSS No. 108. In alternative, you ask that the agency confirm that the auxiliary lamps are permissible, if the distance between the three-lamp cluster and the auxiliary lamps is at least twice the distance that separates each lamp in the cluster. First, we note that auxiliary lamps located immediately adjacent to the three-lamp cluster would not be permitted by FMVSS No. 108 because they would impair the effectiveness of identification lamps. The purpose of the three-lamp cluster requirement is to signal the presence of a large vehicle to other drivers. The number of lamps, three, is a part of the signal, and additional lamps could make the signal less recognizable. Second, while we would generally prefer to establish distance requirements through rulemaking, we recognize the need for guidance with respect to the permissible positioning of auxiliary lamps located between the clearance lamps and the three-lamp cluster. We believe that positioning auxiliary lamps at a distance that is at least twice the distance that separates each lamp in the required three-lamp cluster provides sufficient separation not to impair the effectiveness of the three-lamp cluster (see diagram below). Third, you also asked about installing auxiliary lamps above or below the surface occupied by the three-lamp cluster and the clearance lamps. We note that FMVSS No. 108 does not prohibit auxiliary lamps that are located on a different surface from the three-lamp cluster and the clearance lamps. Specifically, auxiliary lamps may be located on the roof of the truck cab, if the required lamps are located on the sleeper roof above the cab roof. The reverse arrangement is also permissible. In either configuration, the auxiliary lamps are located at a sufficient distance from the required lamps that they would not impair their effectiveness. Finally, we note that the auxiliary lamps must have the same photometric output and be of the same color as the lamps specified in Table II to avoid impairment. We believe that maintaining color and photometric output consistency is important because, for example, the presence of red auxiliary lamps located next to amber clearance lamps could confuse drivers as to the traveling direction of the vehicle. If you need further assistance, please contact George Feygin of my staff at this address or at (202) 366-2992. Sincerely, Jacqueline Glassman ref:108 |
2005 |
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.
