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: aiam5309OpenLawrence P. White, Acting Director Bureau of Motor Vehicles Department of Transportation Commonwealth of Pennsylvania Harrisburg, PA 17122; Lawrence P. White Acting Director Bureau of Motor Vehicles Department of Transportation Commonwealth of Pennsylvania Harrisburg PA 17122; "Dear Mr. White: This responds to your letter of December 13, 1993 asking several questions concerning a recent amendment to Standard No. 217, Bus Emergency Exits and Window Retention and Release (57 FR 49413, November 2, 1992). Your questions and the response to each follows. 1. The effective date - is it the chassis manufacturer's date of completion, the final stage manufacturer's date of completion, or somewhere in between? The effective date for the November 2 final rule is May 2, 1994. Only vehicles manufactured on or after the effective date of an applicable requirement in a Federal motor vehicle safety standard must comply with that requirement. If a vehicle is manufactured in two or more stages, the final stage manufacturer is required to certify that the vehicle complies with 'the standards in effect on the date of manufacture of the incomplete vehicle, the date of final completion, or a date between those two dates.' (49 CFR Part 568.6). 2. Based on the formula for emergency exit space, is the area of the front service door to be included? Does this mean on a vehicle of 60 to 77 passengers, the only additional requirements beyond the front and rear doors is a left side exit door? The November 2 final rule requires additional emergency exit area (AEEA) for some buses. The amount, if any, of AEEA which must be provided is determined by subtracting the area of the front service door and either the area of the rear emergency door or the area of the side emergency door and the rear push- out window, depending on the configuration of the bus (S5.2.3.1). These are the minimum exits required on all buses. If AEEA is required, the first additional exit which must be installed is a left side emergency door (for a bus with a rear emergency door) or a right side emergency door (for a bus with a left side emergency door and a rear push-out window). The number of exits may vary for buses which carry the same number of passengers, because the amount of area credited for each exit is the area of daylight opening, and because different variations of types of exits are possible. However, in the regulatory evaluation for the final rule, the agency estimated that a bus would not be required to have a roof exit (the second type of additional exit required) unless the capacity was greater than 62 (for a bus with a rear emergency door) or 77 (for a bus with a left side emergency door and a rear push-out window). 3. The 'clear aisle space' required for exit to the proposed side emergency door, according to federal specifications, can be met with a flip-up type seat or a clear opening of 12', as measured from the back of the door forward. Are there any specifications, definitions, or descriptions provided as to what would be considered a 'flip seat'? The November 2 final rule allowed a flip-up seat to be adjacent to a side emergency exit door 'if the seat bottom pivots and automatically assumes and retains a vertical position when not in use, so that no portion of the seat bottom is within' the required 12 inch aisle to the exit (S5.4.2.1(a)(2)(ii)). The agency did not otherwise define a flip-up seat, nor did it include any performance requirements for these seats. 4. Also, there is concern regarding school buses that are equipped with the 'flip seat' by the emergency door opening and the possibility of school children, either intentionally or accidently, unlatching the door latch mechanism. Are the door latch mechanisms to be equipped to help prevent this from occurring? Standard No. 217 includes requirements for the type of motion and force required to release an emergency exit (S5.3.3). One of these requirements is that the motion to release a door must be upward from inside the bus (upward or pull-type for school buses with a gross vehicle weight rating of 4,536 kilograms or less). This is intended to lessen the chance of a door accidently being opened, without unnecessarily making the exit more complicated to open in an emergency. In addition, warning alarms are required for door and window exits to notify the driver that the exit has been opened. I hope you find this information helpful. If you have any other questions, please contact Walter Myers of my staff at this address or by phone at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel"; |
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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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ID: aiam1382OpenMr. G. W. Way, Correct Manufacturing Corporation, P.O. Box 689, Delaware, OH 43015; Mr. G. W. Way Correct Manufacturing Corporation P.O. Box 689 Delaware OH 43015; Dear Mr. Way: This is in response to your letter of January 14, 1974, asking abou the category into which a Divco truck would fall and the applicability of Motor Vehicle Safety Standards 121 (Air Brake Systems) and 105a (Hydraulic Brake Systems) to them. The vehicles you have described are 'trucks' for purposes of the safety standards. The applicability of the braking standards is simple: trucks equipped with air brakes must conform to Standard 121, and those equipped with hydraulic brakes must conform to Standard 105a.; I enclose a sheet telling you how to obtain copies of the motor vehicl safety standards and regulations.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2957OpenS. B. Aronson, Pennsylvania Notaries, 625 Stanwix Street, Pittsburgh, PA 15222; S. B. Aronson Pennsylvania Notaries 625 Stanwix Street Pittsburgh PA 15222; Dear Mr. Aronson: This is in response to your letter of January 4, 1979, requesting ou opinion as to whether a rubber stamp which contains the odometer information on the newest Pennsylvania title could be applied to older titles in lieu of having a separate form attached.; There are no legal bars to your recommendation. In fact, the stamp yo recommend makes more sense than a separate form. A separate form can be removed and replaced with another sheet. A stamp cannot be so abused.; We appreciate and support your recommendation. Sincerely, John Womack, 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.