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
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ID: aiam5545OpenMr. Stephen M. Padula Industry Standards and Government Regulations Uniroyal Goodrich Tire Company P.O. Box 2501 Greenville, SC 29602; Mr. Stephen M. Padula Industry Standards and Government Regulations Uniroyal Goodrich Tire Company P.O. Box 2501 Greenville SC 29602; "Dear Mr. Padula: This responds to your letter of March 21, 1995, i which you asked whether it is permissible to have a treadwear grade of 00 or 000 on tires under the Uniform Tire Quality Grading Standards (UTQGS), 49 CFR 575.104. The answer to your question is yes. As you know, the UTQGS currently provide that all new passenger car tires sold in the United States must be graded by their manufacturers or brand name owners for treadwear, traction, and temperature resistance. The grades must be assessed in accordance with paragraphs (d)(1)(i)(A) and (B) of the UTQGS and must be molded into or onto the tire sidewall. Paragraph (d)(2)(i) requires the treadwear grade to be expressed as 2 or 3 digits, representing the percentage (P) of the NHTSA nominal treadwear value, computed as follows: Projected P = mileage x 100 30,000 The percentage derived from the above formula is then rounded off to the nearest lower 20-point increment to arrive at the treadwear grade. In your letter you proposed a hypothetical example of a tire with a projected mileage of 5,000 miles, which would compute as follows: P = 5,000 x 100 = 16.67 30,000 Rounded off to the nearest lower 20-point increment, the treadwear rating for that tire would be 00 or 000. Your example would be correct, if tires still exist that have a projected tread life of 5,000 miles. Although NHTSA has not found any tires so rated, under the current provisions of the UTQGS, it is possible, as demonstrated by your example, to have a UTQGS treadwear rating of 00 or 000. I hope this information is helpful to you. Should you have any questions or need additional information, please feel free to contact Walter Myers of my staff at this address or at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam0317OpenMr. Keitaro Nakajima, General Manager, Toyota Motor Company, Ltd., Lyndhurst Office Park, 1099 Wall Street West, Lyndhurst, New Jersey 07071; Mr. Keitaro Nakajima General Manager Toyota Motor Company Ltd. Lyndhurst Office Park 1099 Wall Street West Lyndhurst New Jersey 07071; Dear Mr. Nakajima: #This is to confirm your understanding that the DO symbol, which represents the tire manufacturer's certification that the tire complies with the passenger car tire standard, is required on tires installed on multipurpose passenger vehicles, if such tires are originally designed and have passenger car tire size designations. However, since Standard No. 110 does not, at the present time, apply to multipurpose passenger vehicles,the responsibility for assuring that these tires contain the DOT symbol is limited to the tire manufacturer. #Sincerely, Lawrence R. Schneider, Acting Chief Counsel; |
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ID: aiam5115OpenThe Honorable Paul David Wellstone United States Senate 2550 University Avenue, West Court International Building St. Paul, MN 55114-1025; The Honorable Paul David Wellstone United States Senate 2550 University Avenue West Court International Building St. Paul MN 55114-1025; Dear Senator Wellstone: Thank you for your letter on behalf of you constituents, Ms. Tutti Sherlock and Ms. Mary Bock, regarding the application of the National Highway Traffic Safety Administration's (NHTSA's) school bus standards to Head Start facilities. Your constituents ask that NHTSA inform the Minnesota Department of Transportation that we do not require school bus manufacturers to provide school bus equipment, such as stop arms and special stop lights, on Head Start buses. They base this request on their belief that in 1985, NHTSA said that states may decide which regulations should apply to Head Start buses. They also believe that stop arms and lights for Head Start buses are unnecessary, and that painting Head Start buses yellow could be confusing. We cannot provide the requested interpretation, because the understanding of your constituents is incorrect. By way of background, your constituents' concerns relate to two sets of regulations, issued under different Acts of Congress. The first of these, the Federal motor vehicle safety standards (FMVSS's) issued under the National Traffic and Motor Vehicle Safety Act ('Safety Act'), apply to the manufacture and sale of new motor vehicles. NHTSA has issued a number of FMVSS's for school buses, including FMVSS's requiring these buses to have a stop arm and warning lights. The Safety Act requires that each person selling a new bus (defined in our regulations as a vehicle designed for 11 or more persons) to a primary, preprimary or secondary school must sell a bus that is certified to the FMVSS's for school buses. State law cannot change this requirement. The question of whether Head Start facilities are 'schools' under the Safety Act has been addressed by NHTSA since the beginning of the school bus FMVSS's. The agency's longstanding position is that Head Start programs are primarily educational in focus rather than custodial, and are therefore 'schools' under the Safety Act. We base this conclusion on a review of the goals and functions of the Head Start program (see, e.g., 45 CFR 1304.1-3), and on past NHTSA interpretations of 'school.' NHTSA has stated its position that Head Start facilities are schools most recently in an August 21, 1992 letter to Mr. Chuck Anderson of the Minnesota Department of Transportation. Any new bus that is sold to a Head Start facility must have the safety features of a school bus at the time of the vehicle's sale, including the stop arm and signal lights. However, the Safety Act does not require Head Start facilities to use school buses or any other particular vehicle, nor does it require school buses to be painted yellow. The maintenance and operational characteristics of school buses are matters left to the individual states. NHTSA's second set of school bus regulations, issued under the Highway Safety Act, is a set of recommendations to the states for developing effective pupil transportation programs. Highway Safety Program Guideline No. 17, 'Pupil Transportation Safety' (copy enclosed), recommends that any vehicle designed for 11 or more persons that is used as a school bus should comply with the FMVSS's for school buses and should be painted yellow. However, Guideline 17 would affect the operation of your constituents' school buses only to the extent that Minnesota has incorporated it into state law. I hope this information will be helpful in responding to your constituents. Sincerely, John Womack Acting Chief Counsel Enclosure; |
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ID: aiam1156OpenMr. Erik Sundelin, Trelleborg Gummifabriks Aktiebolag Fack, S-231 01 TRELLEBORG/Sweden; Mr. Erik Sundelin Trelleborg Gummifabriks Aktiebolag Fack S-231 01 TRELLEBORG/Sweden; Dear Mr. Sundelin: #This is in reply to your letter of May 28, 1973 asking whether you may, consistently with Federal Motor Vehicle Safety Standard No. 109, label maximum load and maximum permissible inflation pressure as follows, using the 165 SR 15 tire size designation as an example: #>>>1. Max Load 1200 Lbs. At 36 psi #2. Max Load 1200 Lbs. At Max Press 36 psi<<< #We do not believe alternative 1 to be consistent with Standard No. 109 because it is not clear that 36 psi is the maximum permissible inflation pressure. Alternative 2 does so indicate, however, and we believe that alternative to be consistent with the standard. #Yours truly, Richard B. Dyson, Assistant Chief Counsel; |
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ID: aiam4354OpenMr. Mark Roberts, 40 East Stillforest, Houston, Texas 77024; Mr. Mark Roberts 40 East Stillforest Houston Texas 77024; Dear Mr. Roberts: This is in reply to your letter of June 9, 1987, with respect to a aftermarket motorcycle lamp that you wish to produce. You refer to the lamp as a 'motorcycle safety light' that would supplement other motorcycle lighting and 'would be a rear facing or all direction light with an amber colored lens that would flash'. You have asked if there are any restrictions or guidelines for such a lamp.; Your letter does not indicate the size, flash rate, or intensity of th light, nor whether you intend it so be installed by motorcycle dealers prior to the first sale, or available only for installation on motorcycles already in use. However, I can give you some general guidelines.; Federal Motor Vehicle Safety Standard No. 108, *Lamp, Reflectiv Devices, and Associated Equipment* contains the requirements that apply to motorcycles and must be met at the time of sale and delivery to their first owner. Generally, except as provided in the standard (*e.g* motorcycle headlamp modulating devices) all lamps must be steady burning in use. Your lamp, however, would flash, and therefore appears precluded as an item of original equipment. Further, vehicle equipment must not impair the effectiveness of lighting equipment required by the standard. Although in the absence of specifications of your lamp we cannot say whether it would impair the effectiveness of required motorcycle lighting equipment, we note that an(sic) rearward facing amber flashing lamp could create confusion with a rearward facing amber turn signal lamp.; As an aftermarket device intended for vehicles in use, your lamp i subject only to the Federal restriction that its installation by a dealer, distributor, or motor vehicle repair business shall not render inoperative in whole or in part other required lighting equipment. Should your device place an excessive drain on a motorcycle battery affecting the operability of other lighting equipment it could be viewed as violative of the Federal restriction. However, even if this question is answered in the negative, the question of the acceptability of the supplemental lamp is determined by the laws of the State in which the device is sold or used. We are unable to advise you on these laws, and suggest that you write American Association of Motor Vehicle Administrators, 1301 Connecticut Ave., N.W., Washington, D.C. 20016, for further information.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam3491Open*AIR MAIL*, Mr. John Osborne, Rolls-Royce Motors, Limited Car Division, Crewe Cheshire, CW1 3PL, England; *AIR MAIL* Mr. John Osborne Rolls-Royce Motors Limited Car Division Crewe Cheshire CW1 3PL England; Dear Mr. Osborne: This is in response to your recent letter to the Administrator regarding Federal Motor Vehicle Safety Standard (FMVSS) No. 208, Occupant Crash Protection, and its related requirements for the comfort and convenience of safety belts.; You stated in reference to paragraph S7.4.4, Latchplate Access, tha *the standard as written is design restrictive in not permitting inboard location of the latchplate when stowed by virtue of requiring the latchplate to be located within the outboard reach envelope...* You requested that the wording be changed to permit either inboard or outboard reach envelopes.; Paragraph S7.4.4 was not intended to limit the location of latchplate to outboard locations. Latchplates located in the outboard reach must be located within the reach envelopes as specified. However, the requirement would not be applicable to latchplates located inboard, since there should be no difficulty in reaching latchplates in this location. It should also be noted that the requirement is not applicable to automatic belts.; We believe the Agency's response to the petitions for reconsideratio of the comfort and convenience requirements will answer your remaining questions. We expect to issue that notice in the very near future.; You requested an early announcement of the final content of FMVSS No 208 as it would apply to automatic restraints. On October 23, 1981, the Department rescinded that portion of the standard that would require automatic restraints. We have enclosed a copy of the news release pertaining to that action for your information.; Please contact this office if you have further questions. Sincerely, Michael M. Finkelstein, Associate Administrator fo Rulemaking; |
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ID: aiam1506OpenMr. Alden G. Olson, Engineer/Transit Technology, Municipality of Metropolitan Seattle, 410 West Harrison Street, Seattle, WA 98119; Mr. Alden G. Olson Engineer/Transit Technology Municipality of Metropolitan Seattle 410 West Harrison Street Seattle WA 98119; Dear Mr. Olson: This responds to your April 2, 1974, request for a ruling on whethe trolley and motor buses equipped with air brake systems and dynamic electric or hydraulic devices are required to be equipped with anti-lock equipment.; Standard No. 121, *Air brake systems*, requires stopping distanc performance which must be met by any bus equipped with air brakes, whether or not it is equipped with supplementary dynamic braking means, and the stops must be made with only controlled wheel lockup over 10 mph. Although the standard does not require antilock devices, many manufacturers have indicated they will use antilock devices to meet this requirement.; In evaluating a vehicle's compliance with the stopping distanc performance requirements of S5.3 and S5.7.2.3, auxiliary braking devices may be utilized in making the stops provided such devices are engaged by means of the same service brake pedal or parking brake control that operates the air brakes. It should be noted, however, that these stops must be made with the transmission selector control in neutral or the clutch disengaged (S6.1.3).; Please write again if this or other difficulties arise in th certification of your buses.; Sincerely, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam4704OpenMr. R.M. Cooper Vice President, Engineering Gillig Corporation Box 3008 Hayward, CA 94540-3008; Mr. R.M. Cooper Vice President Engineering Gillig Corporation Box 3008 Hayward CA 94540-3008; "Dear Mr. Cooper: This responds to your letter asking this agency t consider a problem your company faces with respect to Standard 217, Bus Window Retention and Release (49 CFR 571.217). More specifically, you asked how some of your buses could be certified as complying with the emergency exit labeling requirements set forth in Standard 217 for buses other than school buses. I apologize for the delay in this response. Paragraph S5.5.1 of Standard 217 provides that, in buses other than school buses, each push-out window or other emergency exit shall have the designation 'Emergency Exit' followed by concise operating instructions, describing each motion necessary to unlatch and open the exit, located within 6 inches of the release mechanism. The purpose of this requirement is to identify for bus occupants the location and explain the use of specially-installed emergency exits. As I understand your letter, you have no difficulties providing appropriate instructions in the specified location. Paragraph S5.5.1 continues with the following language: When a release mechanism is not located within an occupant space of an adjacent seat, a label...that indicates the location of the nearest release mechanism shall be placed within the occupant space. The terms 'adjacent seat' and 'occupant space' are defined in S4 of Standard 217 as follows: 'Adjacent seat' means a designated seating position located so that some portion of its occupant space is not more than 10 inches from an emergency exit, for a distance of at least 15 inches measured horizontally and parallel to the exit. 'Occupant space' means the space directly above the seat and footwell, bounded vertically by the ceiling and horizontally by the normally positioned seat back and the nearest obstruction of occupant motion in the direction the seat faces. You stated that many of your buses have seats that face the aisle and that back up against windows designated as emergency exits. These aisle-facing seats are 'adjacent seats' with respect to the emergency exits. The release mechanism for the emergency exit is not within the 'occupant space' for these aisle-facing seats, since the release mechanisms are behind, not above, these seats. You enclosed a group of photographs to further illustrate this situation. Since the release mechanism for the emergency exit is not within the occupant space of these adjacent aisle-facing seats, paragraph S5.5.1 of Standard 217 requires a label indicating the location of the release mechanism for the emergency exit to be placed within the occupant space for these seats. You have noted that the occupant space for these seats does not include any place to which this label could be attached. The nearest obstruction of occupant motion in the direction the aisle-facing seats face is the aisle facing seat on the opposite side of the bus. There are no intervening objects other than narrow vertical stanchions in the center of the aisle. Additionally, you suggested that placing the label on the floor or ceiling of the bus would not serve the purposes of this requirement, since those locations would not be readily visible to the seated occupant in an emergency situation. In response to your letter, we have carefully considered the labeling requirements of S5.5.1 as they apply to aisle-facing seats in front of windows that serve as emergency exits. The final rule adopting this additional labeling requirement explained that NHTSA was concerned that an occupant of an adjacent seat might hinder egress through an emergency exit if the occupant did not know how to use the emergency exit. See 37 FR 9394, at 9395, May 10, 1972. In instances in which the release mechanism itself is not within the occupant space of an adjacent seat, a label within the occupant space directing the occupant of the seat to the emergency exit instructions will help reduce the likelihood that the occupants would inadvertently obstruct egress through the emergency exits. NHTSA's goal of minimizing the likelihood of inadvertent obstruction of emergency exits is equally applicable to forward-facing and aisle-facing seats. However, the means of achieving that goal (i.e., placing a label within the occupant space of an adjacent seat, if the release mechanism is not within that occupant space) may not be equally successful for forward-facing and aisle-facing seats. The agency did not focus upon aisle-facing seats when it adopted this labeling requirement. With respect to forward-facing seats, it is relatively simple to locate a label within the occupant space that will be readily visible both to seated occupants and to persons standing in the aisle, as required by S5.5.2. However, with respect to aisle-facing seats, there may not be any location within the occupant space of such seats where a label could be placed so that the label would be visible to occupants of the seat and to persons standing in the aisle. If the labels were not visible in an emergency, such labels would not further NHTSA's goal of minimizing inadvertent obstruction of emergency exits. Accordingly, we plan to issue a notice proposing to amend and clarify the requirements of S5.5.1 of Standard 217 as they apply to aisle-facing seats. Please note that, unless and until a final rule amending S5.5.1 of Standard 217 becomes effective, the current requirements of S5.5.1 remain in effect for aisle-facing seats. However, the agency believes that it would be inappropriate at this time to enforce the requirement in S5.5.1 that additional information be labeled within the occupant space of aisle-facing seats given the uncertainty that such labels will serve the purpose for which the labeling requirements were established, as noted above. Accordingly, until the agency makes a final decision on the proposed rulemaking mentioned above, NHTSA will not take any enforcement actions against bus manufacturers that do not place a label indicating the location of the nearest emergency exit release mechanism within the occupant space of adjacent aisle-facing seats. Sincerely, Stephen P. Wood Acting Chief Counsel"; |
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ID: aiam3215OpenMr. R. W. Hildebrandt, Group Director Engineering, The Bendix Corporation, 901 Cleveland Street, Elyria, OH 44035; Mr. R. W. Hildebrandt Group Director Engineering The Bendix Corporation 901 Cleveland Street Elyria OH 44035; Dear Mr. Hildebrandt: This responds to your January 22, 1980, letter asking whether section S6.1.8.1 and S6.2.6 of Standard No. 121, *Air Brake Systems*, permit the adjustment, after burnishing, of brakes that are equipped with automatic brake adjusters. The answer to your question is no.; On April 28, 1977, the agency responded to a similar request that yo made for an interpretation of these sections to permit brake adjustment for brakes equipped with automatic adjusters. At that time, the agency stated that the provisions of Standard No. 121 do not permit the type of a brake adjustment that you request. However, the agency noted that it would accept a petition for rulemaking to modify the standard in the manner you suggest if such a petition were supported with sufficient technical data.; In your current request for an interpretation, you merely restate you 1977 letter without offering the necessary supporting data and without petitioning the agency to amend the standard. Accordingly, we must restate the agency's interpretation that the standard does not permit the type of adjustment that you request.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1228OpenMr. C. F. Robb, Manager, Electrical Testing Laboratories, Inc., 2 East End Avenue, New York, NY 10021; Mr. C. F. Robb Manager Electrical Testing Laboratories Inc. 2 East End Avenue New York NY 10021; Dear Mr. Robb: This is in reply to your letter of June 18, 1973, concerning th conformity of certain designs of type III seat belt assemblies with Standard No. 209.; The first feature which you describe is a restraint consisting of waist band with a single shoulder strap. The shoulder strap is attached to the buckle in front and is looped around the waist band in back. Unless this restraint has more elements than you describe, we have serious questions about its conformity with the requirements for type III seat belts under Standard 209. Section S4.1(c) provides that the assembly must restrain the upper torso without shifting the pelvic restraint into the abdominal region and that the upper torso restraint shall be designed to minimize its vertical forces on the shoulders and spine. It appears doubtful that the described assembly meets either of these requirements.; The second feature you describe is a strap through the harness assembl that passes around the seat back and is anchored to the floor by means of the vehicle's seat belt assembly anchorage. Your question appears to be whether such a restraint is a seat back retainer as required by Section S4.1(h). The attachment you describe would not be a seat back retainer under Section S4.1(h).; The third feature described, a closed loop strap without floo attachment would also violate the requirements of S4.1(h), unless it is designed and labeled for use only in specific models having adequate seat back restraints, as specified in that paragraph.; The fourth feature is the ability of a harness to move freely up an down on the restraint strap. This feature is allowable under Standard 209.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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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.