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: nht95-2.4OpenTYPE: INTERPRETATION-NHTSA DATE: March 16, 1995 FROM: Philip R. Recht -- Chief Counsel, NHTSA TO: Harry C. Gough -- P. E., State of Connecticut, Department of Motor Vehicles TITLE: NONE ATTACHMT: ATTACHED TO 3/28/94 LETTER FROM JOHN WOMACK TO THOMAS D. TURNER; ALSO ATTACHED TO 7/7/93 LETTER FROM JOHN WOMACK TO THOMAS D. TURNER; ALSO ATTACHED TO 11/18/94 LETTER FROM HARRY C. GOUGH TO NHTSA CHIEF COUNSEL TEXT: Dear Mr. Gough: This responds to your letter to this office asking whether the retroreflective tape required to outline school bus emergency exits can, in the case of the rear emergency door, be placed on the door itself. The short answer is no. You stated that the State of Connecticut requires that school bus bumpers be black. You further stated that one school bus manufacturer supplied buses with the bottom piece of the retroreflective tape installed on the rear bumper. You then noticed that a number of school buses from a different manufacturer had the bottom part of the tape installed on the door itself. You asked whether the language of S5.5.3 of Federal Motor Vehicle Safety Standard (FMVSS) No. 217, Bus emergency exits and window reten tion and release, permitted the installation of the retroreflective tape on the door itself. Paragraph S5.5.3 of FMVSS No. 217 (49 CFR 571.217) provides: Each opening for a required emergency exit shall be outlined around its outside perimeter with a minimum 3 centimeters wide retroreflective tape, either red, white, or yellow in color, . . . . This requirement was imposed by amendment to FMVSS No. 217 promulgated by a final rule published in the Federal Register on November 2, 1992 (57 FR 49413). In discussing this requirement in the preamble portion of the final rule, we said at 57 FR 49421: Accordingly, the final rule requires a minimum 1 inch wide strip of retroreflective tape, either red, white, or yellow in color, to be placed around the outside perimeter of the emergency exit opening, not the emergency exit itself (emphasis added). As you may know, the buses with the tape on the emergency exit doors have been recalled by the manufacturer. For information about the recall, you can contact the bus manufacturer, Thomas Built Buses, P. O. Box 2450, High Point, NC 27261. Enclosed for your information are two interpretative letters issued by this office on related issues pertaining to the retroreflective tape requirement. See letter to Mr. Thomas D. Turner, Manager, Engineering Services, Blue Bird Body Company, dated July 7, 1993; and letter to Mr. Turner dated March 28, 1994. I hope the above information is helpful to you. Should you have any further questions or need additional information, please feel free to contact Walter Myers of my staff at this address or at (202) 366-2992. Sincerely, |
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ID: 10526Open Mr. Harry C. Gough, P.E. Dear Mr. Gough: This responds to your letter to this office asking whether the retroreflective tape required to outline school bus emergency exits can, in the case of the rear emergency door, be placed on the door itself. The short answer is no. You stated that the State of Connecticut requires that school bus bumpers be black. You further stated that one school bus manufacturer supplied buses with the bottom piece of the retroreflective tape installed on the rear bumper. You then noticed that a number of school buses from a different manufacturer had the bottom part of the tape installed on the door itself. You asked whether the language of S5.5.3 of Federal Motor Vehicle Safety Standard (FMVSS) No. 217, Bus emergency exits and window retention and release, permitted the installation of the retroreflective tape on the door itself. Paragraph S5.5.3 of FMVSS No. 217 (49 CFR 571.217) provides: Each opening for a required emergency exit shall be outlined around its outside perimeter with a minimum 3 centimeters wide retroreflective tape, either red, white, or yellow in color, . . . This requirement was imposed by amendment to FMVSS No. 217 promulgated by a final rule published in the Federal Register on November 2, 1992 (57 FR 49413). In discussing this requirement in the preamble portion of the final rule, we said at 57 FR 49421: Accordingly, the final rule requires a minimum 1 inch wide strip of retroreflective tape, either red, white, or yellow in color, to be placed around the outside perimeter of the emergency exit opening, not the emergency exit itself (emphasis added).
As you may know, the buses with the tape on the emergency exit doors have been recalled by the manufacturer. For information about the recall, you can contact the bus manufacturer, Thomas Built Buses, P. O. Box 2450, High Point, NC 27261. Enclosed for your information are two interpretative letters issued by this office on related issues pertaining to the retroreflective tape requirement. See letter to Mr. Thomas D. Turner, Manager, Engineering Services, Blue Bird Body Company, dated July 7, 1993; and letter to Mr. Turner dated March 28, 1994. I hope the above information is helpful to you. Should you have any further questions or need additional information, please feel free to contact Walter Myers of my staff at this address or at (202) 366-2992. Sincerely,
Philip R. Recht Chief Counsel Enclosures Ref:217 d:3/16/95
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1995 |
ID: 2809oOpen Mr. Paul Scully Dear Mr. Scully: This is in reply to your letter of April 22, l988, asking for a clarification of a letter that this Office sent Wesbar Corporation on March 16, 1988, with respect to the term "effective projected luminous area." Wesbar had asked whether it could include the "illuminated (by the turn signal bulb) reflex reflector portion of the turn signal lens" (Wesbar's language) in its calculation of the l2 square inch minimum effective projected luminous area required by S4.1.1.7 of Safety Standard No. l08. We replied that it could, assuming that the light shines through the reflector. You have pointed out that although a small amount of light escapes through a reflex reflector, the reflector is designed to return light from an outside source, rather than to direct light from a source inside the lamp, and that heretofore agency interpretations (e.g. on October 28, 1970, and October 28, 1979) had expressly excluded reflex reflectors from areas included in the calculation of effective projected luminous area. Reflex reflectors are also excluded from the term by SAE J387 Terminology. We appreciate your calling this matter to our attention. Previous interpretations by this Office clearly indicate that a "reflex reflector" is not to be included in the calculation of effective projected luminous area. We also note that the SAE definition (paragraph 2, SAE J594f, January l977) is incorporated by reference into Standard No. l08, stating that this item of equipment is one that provides an indication of vehicle presence by reflected light (rather than projected light). We are providing a copy of this letter to Wesbar so that it will be apprised of our reevaluation, and our conclusion that the reflex reflector portion of a lens cannot be included in the calculations of the projected luminous lens area. I hope this clarifies the matter for you. Sincerely,
Erika Z. Jones Chief Counsel ref:108 d:8/l9/88 |
1970 |
ID: nht93-5.5OpenTYPE: INTERPRETATION-NHTSA DATE: July 2, 1993 FROM: John Womack -- Acting Chief Counsel, NHTSA TO: Ray Kesler -- Kesler Research Enterprises TITLE: None ATTACHMT: Attached to letter dated 5/17/93 from Ray Kesler to John Womack (OCC 8660) TEXT: This responds to your follow-up letter to the agency in which you request further interpretation of the requirements in Standard No. 111 relating to convex mirrors. Specifically, you asked about how section S5.4.1, which limits the radii of curvature's permissible variance, relates to S12, which specifies the procedures for determining a convex mirror's average radius of curvature. I am pleased to have this opportunity to respond to your request. As Marvin Shaw of my staff informed your associate Lawrence Hufstedler in a telephone conversation, section S12 sets forth a detailed multi-step procedure for calculating a convex mirror's average radius of curvature. The first step is to take ten readings on the mirror surface with a 3-point linear spherometer as specified in Figure 1 of the Standard. (See S12.1.) The second step is to convert each of the ten readings to a "radius of curvature calculation" using Table 1. (See S12.5.) The third step is to calculate the "average radius of curvature" by adding all 10 radius of curvature calculations and dividing by 10. (See S12.6.) Mr. Hufstedler asked how S5.4.1 affects the calculations. That section states "none of the radii of curvature readings shall deviate from the average radius of curvature by more than 12.5 percent." This means that some of the radii of curvature readings may be up to 12.5 percent different than the average radius of curvature. In numerical terms, this means that if a mirror had an average radius of curvature of 36 inches a given radii of curvature reading could be as low as 31.5 inches and as high as 40.5. I hope this information is helpful. Please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992 if you have any further questions or need additional information. |
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ID: 8660Open Mr. Ray Kesler Dear Mr. Kesler: This responds to your follow-up letter to the agency in which you request further interpretation of the requirements in Standard No. 111 relating to convex mirrors. Specifically, you asked about how section S5.4.1, which limits the radii of curvature's permissible variance, relates to S12, which specifies the procedures for determining a convex mirror's average radius of curvature. I am pleased to have this opportunity to respond to your request. As Marvin Shaw of my staff informed your associate Lawrence Hufstedler in a telephone conversation, section S12 sets forth a detailed multi-step procedure for calculating a convex mirror's average radius of curvature. The first step is to take ten readings on the mirror surface with a 3-point linear spherometer as specified in Figure 1 of the Standard. (See S12.1.) The second step is to convert each of the ten readings to a "radius of curvature calculation" using Table 1. (See S12.5.) The third step is to calculate the "average radius of curvature" by adding all 10 radius of curvature calculations and dividing by 10. (See S12.6.) Mr. Hufstedler asked how S5.4.1 affects the calculations. That section states "none of the radii of curvature readings shall deviate from the average radius of curvature by more than 12.5 percent." This means that some of the radii of curvature readings may be up to 12.5 percent different than the average radius of curvature. In numerical terms, this means that if a mirror had an average radius of curvature of 36 inches a given radii of curvature reading could be as low as 31.5 inches and as high as 40.5. I hope this information is helpful. Please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992 if you have any further questions or need additional information. Sincerely,
John Womack Acting Chief Counsel ref:#111 dL7/2/93 |
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ID: aiam3619OpenMr. Robert C. Craig, Quality Control Manager, Cosco, 2525 State Street, Columbus, IN 47201; Mr. Robert C. Craig Quality Control Manager Cosco 2525 State Street Columbus IN 47201; Dear Mr. Craig: This responds to your letter of August 13, 1982, concerning th application of the belt buckle requirements of Standard No. 209, *Seat Belt Assemblies*, to child restraints meeting Standard No. 213, *Child Restraint Systems*. As explained in the enclosed letters of interpretation of May 12, 1981, and May 21, 1981, the only requirements of Standard No. 209 that apply to child restraint belt buckles are the corrosion resistance requirement of S4.3(a) and the temperature resistance requirement of S4.3(b). The buckle release requirements of S4.3(d) and the buckle latch requirements of S4.3(g) do not apply to child restraints.; Because of reports of problems relating to difficulty in operatin child restraint buckles, the agency is considering issuance of a proposal to apply the requirements of S4.3(d)(2) and S4.3(g) to child restraint system belt buckles. Any such proposal would be published in the *Federal Register* to provide all interested parties with notice and opportunity to comment.; If you have any further questions, please let me know. Sincerely, Frank Berndt, Chief Counsel |
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ID: nht93-4.34OpenDATE: June 15, 1993 FROM: John Womack -- Acting Chief Counsel, U.S. Department of Transportation, NHTSA TO: Edward F. Conway, Jr. -- Assistant General Counsel, Recreation Vehicle Industry Association TITLE: None ATTACHMT: Attached to letter dated 5-19-93 from Edward F. Conway, Jr. to John Womack. TEXT: We have received your letter of May 19, 1993, asking for an interpretation of Motor Vehicle Safety Standard No. 108. You are concerned with an opinion that the agency expressed when it published the rule requiring center highmounted stoplamps (CHMSLs) on trucks whose overall width is less than 80 inches and whose GVWR is 10,000 pounds or less that are manufactured on and after September 1, 1993 (56 FR 16015). NHTSA pointed out that installation of an aftermarket slide-in camper by a manufacturer, dealer, distributor, or motor vehicle repair business might "render inoperative" the CHMSL within the meaning of the prohibition of 15 U.S.C. 1397(a)(2)(A) if it obscured the original equipment CHMSL. You have apprised us that a number of your manufacturer members produce slide-in campers that are more than 80 inches wide that obscure CHMSLs. When these campers are installed on trucks that are 80 inches or less in overall width, you argue that "(a) CHMSL is NOT required on that pickup truck because its overall width is now MORE THAN 80 inches". You ask that we concur in your conclusions that these campers may lawfully be installed by a person other than a vehicle owner, and that these campers themselves are not required to be equipped with a CHMSL. We are pleased to inform you that we concur with your conclusions under the conditions to be discussed. Virtually all modifications of vehicles in use by persons other than the owner are subject to the "render inoperative" prohibition. Over the years, we have informed prospective modifiers that we do not interpret the prohibition to require continued compliance to all Federal motor vehicle safety standards (FMVSS) that originally applied to the vehicle to be modified if the modifications contemplated will result in a change in the applicability of the original FMVSS. For example, if a 1990 passenger car is changed from a closed car to an open one, it need no longer meet all FMVSS that applied to closed vehicles manufactured in 1990. However, at the end of the modification process, it must meet all FMVSS that applied to convertibles in that year. In our opinion, the same principle applies in the fact situation you have outlined. A pickup truck with an overall width of 80 inches or more is not required to have a CHMSL, but it is required to be equipped with clearance and identification lamps. The descriptive literature that you enclosed on "hardside" and "folding" campers shows that each camper is equipped with clearance and identification lamps, so that the lighting equipment requirements for wide trucks will be met when the campers are installed. Therefore, if a camper whose overall width is 80 inches or more is equipped with clearance and identification lamps, it is not required to be equipped with a CHMSL, and its installation by a person other than the vehicle owner will not be a violation of 15 U.S.C. 1397(a)(2)(A) even if the CHMSL on the pickup carrying the camper is obscured. |
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ID: nht87-1.11OpenTYPE: INTERPRETATION-NHTSA DATE: 01/12/87 FROM: AUTHOR UNAVAILABLE; Erika Z. Jones; NHTSA TO: A.L. Bragg TITLE: FMVSS INTERPRETATION TEXT: Ms. Erika Jones Chief Counsel UNITED STATES DEPARTMENT OF TRANSPORTATION NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION 400 7th Street Southwest Washington, D.C. 20590 Subject: INTERPRETATION OF PARAGRAPH S4.1.1.3 WHICH STATES: "INTERMEDIATE SIDEMARKER DEVICES ARE NOT REQUIRED ON VEHICLES LESS THAN 30 FEET IN OVERALL LENGTH" Dear Ms. Jones: We would appreciate it if you could clarify the above referenced section of 108 as it pertains to both tables 2 and 3 which state that trailers, both under 80 and over 80 inches, require intermediate side marker lamps. However, a footnote in both of thes e tables points out paragraph S4.1.1.3 which does not require intermediate sidemarkers on vehicles less than 30 feet in overall length. Our question is in regard to the proper interpretation of vehicles less than 30 feet in overall length. In the case of trailers, does this mean just the trailer as it sits by itself or does it include the power unit that may be pulling the trailer? In the case of straight trucks, that is, trucks in which the power unit and the trailer are not separable, our understanding is that the overall length refers to everything between the front and the rear bumpers. Thank you for your comments. Please feel free to contact us if there are any questions. Sincerely, TRUCK-LITE CO., INC. A.L. Bragg Laboratory Manager ALB/bme cc: B. Yorks J. Swanson J. Latona B. Maternowski Mr. A. L. Bragg Laboratory Manager Truck-Lite Co., Inc 310 East Elmwood Ave. Falconer, NY 14733 Dear Mr. Bragg: This is in reply to your letter of October 14, 1986, in which you ask how the overall length of vehicles is calculated in determining whether they are to be equipped with intermediate side marker lamps. With respect to trailers, you ask whether overall length includes the towing unit. No, the overall length to be calculated is only that of the trailer. As for trucks, you assume that overall length "refers to everything between the front and rear bumpers." I assume that you are including the bumpers in the quoted phase, and that would be correct. If you have any further questions we would be pleased to answer them. Sincerely, Erika Z. Jones Chief counsel |
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ID: 10914-2Open Ms. Jane L. Dawson Dear Ms. Dawson: This responds to your letter to Walter Myers of this office regarding the May 9, 1995, amendment of Federal Motor Vehicle Safety Standard (FMVSS) No. 217, Bus Window Retention and Release. I apologize for the delay in responding. For your future reference, Mr. Myers is no longer assigned to our school bus standards. You may address requests for interpretation directly to me. The May 9 amendment (60 FR 24562) to FMVSS No. 217 permitted, among other things, bus manufacturers to meet the additional emergency exit area (AEEA) requirements of S5.2 by permitting manufacturers to install two emergency exit windows as an alternative to an emergency exit door. You asked what the location requirements (fore and aft) are for the emergency windows that are used as the first additional emergency exit. FMVSS No. 217 contains no explicit fore and aft location requirements for the two additional emergency exit windows. However, the intent of the final rule was to substitute the location requirements of the side exit door when the windows are used to satisfy the requirement for the first additional emergency exit. This intention is reflected in the use of the conjunctive word "or" in Tables 1 and 2 of the May 9, 1995, amendment. If a left side exit door would have been installed pursuant to S5.2.3.1(a)(2)(i), then S5.2.3.2(a)(2) requires that it be located as near as practicable to the midpoint of the passenger compartment. The same fore-aft location should be used for the windows. In cases where the fore-aft location is not specified, such as a right side exit door installed pursuant to S5.2.3.1(b)(2)(i), then the windows should be placed so as to provide bus passengers with maximum accessibility to an emergency exit, in accordance with what is reasonable and practicable. Also note the explicit location requirement in S5.2.3.2(c) that exit windows be evenly divided between the left and right sides of the bus. For example, if two exit windows are used instead of a left side exit door, they should be placed on opposite sides at the midpoint of the bus. I hope this information will be of assistance to you. Should you have any further questions or seek additional information, please feel free to contact Paul Atelsek at this address or by calling (202) 366- 2992. Sincerely,
John Womack Acting Chief Counsel
ref:217 d:8/4/95
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1995 |
ID: aiam0881OpenMr. W. Dershko, Engineering Manager, Motor Coach Industries, Inc., Pembina, ND 58271; Mr. W. Dershko Engineering Manager Motor Coach Industries Inc. Pembina ND 58271; Dear Mr. Dershko: This is in response to your requests of July 12 and August 25, 1972 for interpretations of Standard No. 217, Bus Window Retention and Release. I regret the delay in our response.; *S5.1.2* Minimum Surface Dimensions The installation of a metal bar across the rear corner windows so tha the minimum surface dimension between the bar and the edge of the glazing would be less than 8 inches would exclude the window from the window retention requirements of S5.1, as you suggest.; *S5.3.2* Emergency Exit Release The motion of the release mechanism, which you clarified in a telephon conversation on October 13 with Mr. Kevin Cavey of the Motor Vehicle Programs staff at NHTSA, meets the directional and clearance requirements of S5.3.2, since the initial motion is perpendicular to the exit surface and the required 2-inch clearance is afforded during the operation of the mechanism.; *S5.5.2* Emergency Exit Identification You are correct in your assumption that normal nighttime illuminatio may include reading lights and that it is not the intent of the standard to require self-illuminated exit identification.; *Figure 3* Access Regions for Exits Without Adjacent Seats You are correct in assuming that Figure 3B requires a 2-inch clearanc around the release mechanism and is not intended to specify the required outline for a rear shelf.; Sincerely yours, Richard B. Dyson, Assistant Chief Counsel |
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.