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: aiam1308OpenMr. Roy Stolpestad, 700 North Bryant Ave., #802, Minneapolis, MN 55411; Mr. Roy Stolpestad 700 North Bryant Ave. #802 Minneapolis MN 55411; Dear Mr. Stolpestad: This is in reply to your letter of October 11, 1973, concerning th 1966 Chrysler you recently purchased from Central Motors in Minneapolis.; As Miss Porter correctly pointed out in her column, the Federal law o odometer fraud enables you to bring a civil action against Central. The amount of recovery in such an action can be substantial. If the court were to accept your estimate of damages of $1490.24, the damages assessable under Federal law would be three times that amount - $4470.72. In no case would damages be less than $1500, a minimum value established by law. In addition, if you are successful, Central must pay your attorney fees as well as all court costs.; I appreciate your concern for the costs of litigation. However, b providing for the payment of attorney fees the odometer law places you in a better position than a personal injury litigant, whose recovery is usually diminished by his attorney's contingency fee. Your best course at this point is therefore to retain counsel if Central persists in its refusal to reimburse you.; By way of advice to your attorney, I would point out that the 'out that Central claims to have taken -- checking the box on the disclosure form that indicates the true mileage is unknown -- was taken too late to be of benefit to them. The Federal regulation governing disclosure requires the disclosure statement to be made 'before executing any transfer of ownership form.' If they mailed the statement the next day, their disclosure was untimely. Moreover, the representations made in the newspaper advertisment (sic) are evidentiary of their representation of 33,000 miles as being the true mileage on the vehicle. Your success in finding the previous owner is also useful in establishing that the actual mileage was greater than shown.; We will be willing to give you or your attorney further advice i questions arise concerning the intent and effect of the Federal odometer law. The enclosed copies of the law and regulations are provided to assist him in representing you.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2877OpenMr. Ken Yoneyama, Chief Engineer, Bridgestone Research Inc., 350 Fifth Ave., Suite 4202, New York, NY 10001; Mr. Ken Yoneyama Chief Engineer Bridgestone Research Inc. 350 Fifth Ave. Suite 4202 New York NY 10001; Dear Mr. Yoneyama: This is in response to your letter of September 22, 1978, askin whether tires listed in Table 1-A of Appendix A, Federal Motor Vehicle Safety Standard No. 109, *New Pneumatic Tires - Passenger Cars*, must comply with Part 575.104, *Uniform Tire Quality Grading Standards*, (UTQGS), if the tires are installed as original equipment on multi-purpose passenger vehicles. You also inquire as to the effective dates for the provision of UTQGS information to first purchasers of new motor vehicles under Part 575.104(d)(1)(iii).; UTQGS applies to a tire type whose predominant contemplated use is o passenger cars, even if the manufacturer knows the tire type is also used as original equipment on multi-purpose passenger vehicles. A manufacturer's determination to certify a tire as conforming to Standard No. 109, will also determine the tire's classification for purposes of UTQGS. Thus, UTQGS would apply to any tire labeled with a size designation listed in Appendix A of Standard No. 109, other than a deep tread, winter-type snow tire or space- saver or temporary use spare tire, regardless of the tire's actual use.; On October 23, 1978, NHTSA issued a *Federal Register* notice (cop enclosed) granting the petition of American Motors corporation to revise the effective dates for Part 575.104(d)(1)(iii) to September 1, 1979 for bias-ply tires and March 1, 1980 for bias-belted tires. On the basis of this change, your statement regarding effective dates is correct.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam3765OpenMs. Patricia Hill, 2150 Hacker Road, Howell, MI 48843; Ms. Patricia Hill 2150 Hacker Road Howell MI 48843; Dear Ms. Hill: This responds to your March 23, 1983, letter asking five specifi questions relating to Standard No. 302, *Flammability of Interior Materials*. Your questions and their answers are listed below:; 1. Provide a definitive interpretation of 'erratic burning' as used i the subject standard that may be related to a test procedure.; 'Erratic burning,' as that term is used in the standard, relates t incidents where the material may soften or bend at the flaming end in a way that would not allow for uniform burning. Erratic burning, therefore, includes, but is not limited to, nonuniform burning as indicated in S5.1.3 of the standard where the use of support wires is mentioned.; 2. Provide a definitive interpretation of the word 'anticipate' as use in TP 302-02. That is, must the expectation of a softening and bending of the flaming end be based upon an actual test of an identical test specimen? A similar test specimen?; In actual practice, a test specimen is observed while burning during compliance test to FMVSS No. 302. If the specimen is found both to soften and bend at the flaming end during testing and also fails to meet the minimum burn rate requirement, a retest is performed using support wires.; 3. Does the agency still plan to issue an interpretive amendmen limiting or clarifying the use of support wires as stated in your 1976 letter? When?; The agency currently has no plans for any modifications of Standard No 302.; 4. How do the procedural requirements of the subject standard apply t a test specimen that bends at the flaming end prior to ignition by a bunsen burner?; We are not certain of the question that you are asking. The materia would not have a flaming end to bend prior to ignition of the bunsen burner. If by this question you mean to ask what we would do about non-flat test specimens, the agency always attempts to test flat specimens only.; 5. Does the NHTSA plan to revise TP 302-02 to reflect your 197 interpretation and your response to this letter? When?; The agency currently has no plans for any modifications to TP 302- 02. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1758OpenMr. Philip P. Friedlander, Jr., Director of Communications, Dealer News, 1343 L Street, N.W., Washington, D.C. 20005; Mr. Philip P. Friedlander Jr. Director of Communications Dealer News 1343 L Street N.W. Washington D.C. 20005; Dear Mr. Friedlander: This is in reply to your letter of December 24, 1974, forwarding to u a copy of an article in the December 23-30, 1974, issue of the NTDRA *Dealer News*, which attempts to clarify an earlier article interpreting the labeling requirements of Motor Vehicle Safety Standard No. 117.; We believe your revised article is still somewhat unclear i interpreting the requirements, and we would like to clarify these requirements for you.; >>>*THE FOLLOWING REQUIREMENTS ARE PRESENTLY EFFECTIVE*<<< The casing, before retreading, must contain in a permanent fashion, th following: the symbol 'DOT', the size of the tire, and the actual number of plies or ply rating.; The completed retread must be labeled,either permanently or with a affixed label that is not easily removable, with the following: the tire's size designation, its maximum permissible inflation pressure, the actual number of plies, ply rating or both, the words 'tubeless' or 'tube type,' as appropriate, the word radial, if the tire is of radial construction, and if the tire is of bias-belted construction, the words 'bias belted' *or* the actual number of plies in the sidewall and the actual number of plies in the tread area.; The completed retreaded tire must be permanently labeled only with it maximum permissible load. Permanent labeling includes molding, branding, or other method that will produce a permanent label, and includes any original casing label that is retained through the retread process.; >>>*THE FOLLOWING REQUIREMENTS ARE EFFECTIVE MAY 12, 1975*<<< The casing before retreading must contain in a permanent fashion th following: the symbol 'DOT', the size of the tire, and the actual number of plies or ply rating. These requirements are the same as those presently in effect.; The completed retread must be labeled, either permanently or with a affixed label that is not easily removable, with the following: the tire's size designation, its maximum permissible inflation pressure, the words 'tubeless' or 'tube type' as appropriate, and the word 'radial' if the tire is of radial construction.; The completed retread must be permanently labeled only with th following: the tire's maximum permissible load, the actual number of plies in the tire sidewall, and the actual number of plies in the tire tread area, if different, and the generic name of each cord material used in the plies (both sidewall and tread area) of the tire.; The changes made by the amendment published November 12, 1974 (39 F 39882), which are effective May 12, 1975, are, in summary, that (1) the labeling of the actual number of plies in the sidewall, and tread area if different, must after May 12, 1975, be permanently labeled, and (2) the generic names of each cord material, which prior to May 12, 1975, is not required to be labeled at all, must after May 12, 1975, be permanently labeled.; We believe some further clarification of the requirements should b conveyed to your readers.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam5062OpenMr. Jerry Beck One Leatherwood Court Burtonsville, MD 20866; Mr. Jerry Beck One Leatherwood Court Burtonsville MD 20866; "Dear Mr. Beck: This responds to your letter requesting informatio about how this agency's regulations would apply to the product you are developing. While you initially requested that the agency keep your inquiry confidential, you removed this request for confidentiality in a September 18, 1992 letter to Marvin Shaw of my staff. You described your product as a reflective decal that would be placed on the backside of a motor vehicle's rear view mirror and on its rear bumper. I am pleased to have this opportunity to explain our requirements to you. I am also enclosing a copy of a fact sheet entitled 'Information for New Manufacturers of Motor Vehicles and Motor Vehicle Equipment.' By way of background information, NHTSA is authorized to issue Federal Motor Vehicle Safety Standards that set performance requirements for new motor vehicles and items of motor vehicle equipment. Section 102(4) of the Safety Act defines, in relevant part, the term 'motor vehicle equipment' as: any system, part, or component of a motor vehicle as originally manufactured or any similar part or component manufactured or sold for replacement or improvement of such system, part, or component or as any accessory, or addition to the motor vehicle ... In determining whether an item of equipment is considered an accessory, NHTSA applies two criteria. The first criterion is whether a substantial portion of the expected use of the item is related to the operation or maintenance of motor vehicles. We determine the expected use by considering product advertising, product labeling, and the type of store that retails the product, as well as available information about the actual use of the product. The second criterion is whether the product is intended to be used principally by ordinary users of motor vehicles. If the product satisfies both criteria, then the product is considered to be an 'accessory' and thus is subject to the provisions of the Safety Act. Applying these criteria to your reflective decals, it appears that your product would be an accessory and thus an item of motor vehicle equipment under the Safety Act. Based on our understanding of your letter, it appears that a substantial portion of your device's expected use will be during the operation of a motor vehicle. In addition, it appears that your product would typically be used by ordinary users of motor vehicles. While your device would be considered an item of motor vehicle equipment, this agency has not issued any standards setting forth performance requirements for such a device. Nevertheless, any person that installed this device on a new vehicle before the vehicle's first sale to the public would be required to certify that the vehicle complies with all applicable safety standards, including Standard No. 111, Rearview Mirrors, with this device installed. After the first sale of the vehicle to the public, certain persons who modify vehicles are subject to the prohibition in section 108(a)(2) of the Safety Act (15 U.S.C. 1397(a)(2)). That section provides that: 'No manufacturer, distributor, dealer, or motor vehicle repair business shall knowingly render inoperative, in whole or in part, any device or element of design installed on or in a motor vehicle or item of motor vehicle equipment in compliance with an applicable Federal motor vehicle safety standard...' To avoid a 'rendering inoperative' violation for vehicles that comply with any of our safety standards, commercial after market installers of your device should examine any installation instructions that you may have for your device and compare those instructions with the requirements of our safety standards, to determine if installing the device in accordance with those instructions would result in the vehicle no longer complying with any of those safety standards. If the installation of your device would not result in a 'rendering inoperative' of the vehicle's compliance with the safety standards, the device can be installed by manufacturers, distributors, dealers and repair shops without violating any Federal requirements. The prohibitions of Section 108(a)(2)(A) do not apply to the actions of a vehicle owner in modifying his or her vehicle. Thus, a vehicle owner would not violate the Safety Act by installing your device even if doing so would adversely affect some safety feature in his or her vehicle. You should be aware that, as a manufacturer of an aftermarket item of motor vehicle equipment, you are subject to the requirements in sections 151-159 of the Safety Act concerning the recall and remedy of products with defects related to motor vehicle safety. In the event that you or NHTSA determines that your product contains a safety related defect, you would be responsible for notifying purchasers of the defective equipment and for remedying the problem free of charge. I hope this information is helpful. If you have any further questions about NHTSA's safety standards, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992. Sincerely, Paul Jackson Rice Chief Counsel Enclosure"; |
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ID: aiam1888OpenHonorable Birch Bayh, United States Senate, Washington, DC 20510; Honorable Birch Bayh United States Senate Washington DC 20510; Dear Senator Bayh: This is in response to your letter requesting information concernin correspondence from Mr. James A. Graham, commenting on a proposed amendment to the Federal bumper standard.; On January 2, 1975, the National Highway Traffic Safety Administratio (NHTSA) issued a *Federal Register* notice (copy enclosed) proposing to reduce the current 5-mph bumper impact requirements to 2.5 mph until the 1979 model year. The impact requirements would have been increased to 4 mph for 1979 and later model year cars.; The proposal was based primarily on the results of two agency-sponsore studies which indicated that the cost and weight of many current production bumpers, in light of inflation and fuel shortages, made the bumpers no longer cost beneficial. Information presented at public hearings on the bumper notice and comments submitted to the docket in response to the proposal have brought to light additional data. The NHTSA has carefully examined all of this evidence and reviewed its studies in light of the new information. As a result, the agency has concluded that the 5 mph protection level should not be reduced. This decision is contained in a *Federal Register* notice that was published on March 12, 1975 (Docket No. 74-11, Notice 7, Docket No. 73-19, Notice 6).; In his letter Mr. Graham objects to the standard's regulation o surface damage, such as dents, stating that this is not the type of damage which should be addressed by an agency developing safety standards. The surface damage criteria are proposed as part of a standard being promulgated under Title I of the Motor Vehicle Information and Cost Savings Act (Pub. L. 92-513). The Cost Savings Act directs the National Highway Traffic Safety Administration to develop a bumper standard that will obtain the maximum feasible reduction of costs to the public and the consumer. As such, the standard is not to be limited to affecting safety-related damage. Factors such as insurance costs and consumer time and inconvenience are to be considered in the rulemaking as well.; Mr. Graham's comments will be placed in the public docket where the will receive every consideration.; We appreciate your interest and that of Mr. Graham in this area o motor vehicle safety and performance.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam5598OpenMr. Kenneth Zawlocki 7028 Laurel Oak Way Fair Oaks, CA 95628; Mr. Kenneth Zawlocki 7028 Laurel Oak Way Fair Oaks CA 95628; "Dear Mr. Zawlocki: This responds to your request for an interpretatio of Standard No. 218, Motorcycle Helmets. Your questions are addressed below. You first ask whether the Penetration Test (S7.2) tests the outer shell of the helmet, the Impact Attenuation Test (S7.1) tests inner protection materials, and the Retention System Test (S7.3) tests straps that hold the helmet on the head. Each of these tests measures the performance of a motorcycle helmet as a total system, i.e., the tests are conducted on a motorcycle helmet as a whole, rather than on helmet components. Therefore, the tests are not limited to measuring the performance of the components you cite. By way of example, while the shell of the helmet may play a critical role in a helmet's resistance to penetration, the composition and thickness of the liner may also be important. Similarly, while certain components are more important than others in meeting certain criteria, overall design and construction of the helmet will determine whether it meets the impact attenuation and retention requirements. You next ask whether Standard No. 218 specifies the types or amounts of material to be used in manufacturing helmets. Standard No. 218 specifies performance requirements for motorcycle helmets. A manufacturer may use any types or amounts of materials that enable the manufacturer to fully comply with the standard. While Standard No. 218 does not specify that certain materials must be used in manufacturing a helmet, the National Highway Traffic Safety Administration's (NHTSA) experience in over 20 years of helmet testing indicates that helmets meeting Standard No. 218 have common characteristics. The first of these is a dense foam liner that is approximately one inch thick. Helmets with thinner liners or liners composed of a soft compressible foam are not likely to meet the impact attenuation or penetration requirements of the Standard. The weight of the helmet, while not governed by any section of Standard No. 218, is also a good indicator of how it will perform in testing. Although it may be technically possible to build a lightweight helmet that satisfies the performance requirements of Standard No. 218, NHTSA is not aware of any motorcycle helmet weighing less than three pounds that has done so. Finally, you ask whether Standard No. 218 precludes decorating a helmet with any material such as leather or cloth, or with items such as wigs, flowers, decals or hats. The various helmet decorations you describe could affect a motorcycle helmet's compliance with a variety of Standard No. 218's performance requirements. One example is S5.5, Projections. The inside of the shell must be free of protruding rivets or other projections. The presence of any projections within the helmet indicates that it is not a complying helmet. Projecting snaps or other objects are permitted on the outside of the helmet only if they are required for essential accessories such as visors or face shields. Any projection on the outside of a helmet must not protrude more than five millimeters. I note that under 49 U.S.C. 30112(a), 'a person may not manufacture for sale, sell, offer for sale, introduce or deliver for introduction in interstate commerce, or import into the United States' a new motorcycle helmet that does not comply with Standard No. 218. Also, dealers and repair businesses may not modify new or used motorcycle helmets in a manner that results in the helmet no longer complying with the standard. Any of these parties must therefore ensure that any contemplated decorations would not affect a helmet's compliance with Standard No. 218. Federal law does not address modifications made by a motorcycle helmet owner to his or her own helmet. However, it is NHTSA's policy to discourage motorcycle helmet users from modifying their helmets. This is because even relatively simple modifications can reduce the safety protection provided by the helmet. S5.6.1(f)(3) of Standard No. 218 requires the following instruction to be placed on helmets: 'Make no modifications...' I also note that State laws may address modifications made by motorcycle helmet owners to their own helmets. I hope this information is helpful. If you have further questions, please contact Dorothy Nakama of my staff at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam0260OpenMr. Louis C. Lundstrom, Director, Automotive Safety Engineering, General Motors Engineering Staff, General Motors Technical Center, Warren, MI 48090; Mr. Louis C. Lundstrom Director Automotive Safety Engineering General Motors Engineering Staff General Motors Technical Center Warren MI 48090; Dear Mr. Lundstrom: This is in reply to your letter to Mr. Toms of October 15, 1970, i which you asked whether General Motors could provide one consumer information document to fleet purchasers of motor vehicles, rather than putting a booklet in each car as is done in the usual case.; The answer is yes. 49 CFR 575.6(a) requires that the information b provided 'to that purchaser', 'at the time a motor vehicle is delivered' to him. It does not require that the information be in the vehicle, or that there be one booklet per vehicle.; We are pleased to be of assistance. Sincerely, Rodolfo A. Diaz, Acting Associate Director, Motor Vehicl Programs; |
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ID: aiam5432OpenMr. Thomas D. Turner Manager, Engineering Services Blue Bird Body Company P.O. Box 937 Fort Valley, GA 31030; Mr. Thomas D. Turner Manager Engineering Services Blue Bird Body Company P.O. Box 937 Fort Valley GA 31030; "Dear Mr. Turner: This responds to your letter of May 2, 1994 requesting an interpretation of how the term 'daylight opening,' as used in a recent amendment of Standard No. 217, Bus Emergency Exits and Window Retention and Release, would apply to various exits (57 FR 49413, November 2, 1992, and 57 FR 57020, December 2, 1992). Your letter references a March 24, 1994 interpretation letter to Mr. Bob Carver of Wayne Wheeled Vehicles. That letter discussed the term 'daylight opening' as follows: The term 'daylight opening' is defined in the Final Rule as 'the maximum unobstructed opening of an emergency exit when viewed from a direction perpendicular to the plane of the opening.' An obstruction in this context would include any obstacle or object that would block, obscure, or interfere with, in any way, access to that exit when opened. In determining the 'maximum unobstructed opening of an emergency exit,' we would subtract, from the total area of the opening, the area of any portions of the opening that cannot be used for exit purposes as a result of the obstruction. The area measurements would be taken when viewed from a direction perpendicular to the plane of the opening. Your letter states that this interpretation represents a drastic change in what we understood from the wording of the final rule ... and what we were told by Rulemaking. We believed and were told that the definition of daylight opening applied to the exit opening itself and did not involve access to the opening. Access to and obstruction of openings are addressed later in the standard in section S5.4.2 School Bus Emergency Exit Extension. Before answering your specific questions, I would like to respond to these statements. You are correct that S5.4.2 includes requirements related to access to, and obstruction of, exits in that it specifies the minimum opening and the minimum amount of access required for various exits. However, the issue of minimum opening is separate from the issue, addressed in S5.2.3, of the maximum amount of area credited for any opening. Section S5.2.3 specifies the number and type of exits required on school buses. This section states: The area in square centimeters of the unobstructed openings for emergency exit shall collectively amount to at least 432 times the number of designated seating positions in the bus. The amount of emergency exit area credited to an emergency exit is based on the daylight opening of the exit opening. Thus, S5.2.3 specifies the maximum amount of area credited for any opening. An interpretation of the term 'daylight opening' that allowed credit for the exit opening, regardless of obstructions, would be contrary to the plain language of the definition of that term. Giving credit for obstructed areas would also be contrary to the intent of the final rule, which is to increase the area on larger buses which is available for exit in an emergency. With respect to your report of receiving an oral interpretation from agency staff, I would also like to emphasize that, to the extent the public has any questions concerning the meaning of any NHTSA standard or regulation, the only agency interpretations which are authoritative and which therefore can be relied upon by members of the public, such as manufacturers, are those issued in writing by the Chief Counsel. We have reminded agency staff not to make formal, or informal, oral statements that might misinterpreted by manufacturers as official agency guidance on which they may safely rely. Your letter states that the March 24 interpretation 'raises other questions regarding the various school bus emergency exits.' Your questions and the response to each follows. By way of background information, NHTSA does not approve motor vehicles or motor vehicle equipment. The following represents our opinion based on the facts provided in your letter. Rear Emergency Exit Door a. Section S5.4.2.1(a)(1) ... requires unobstructed passage of a rectangular parallelepiped 30 centimeters deep. It is our rationale and interpretation that a seat back or other interior component that lies forward of this 30 centimeter deep parallelepiped is not an obstruction to the rear emergency door and would not result in a reduction of the area credited to the rear emergency door. (See figure 1a) Is this interpretation correct? In the case of a rear emergency exit door, the depth requirement in S5.4.2.1(a)(1) reflects a determination that an interior component outside that limit does not render the exit unusable. Therefore, an interior component outside the area bounded by the transverse vertical plane of the exit opening, the two longitudinal vertical planes tangent to the sides of the exit opening, and the transverse vertical plane parallel to and 30 centimeters away from the plane of the exit opening would not be considered an obstruction for determining the area of 'daylight opening.' b. School buses are typically equipped with 39-inch (99 cm) wide seats. At the rear emergency door, one of the rear seats is typically shifted forward to provide the clearance required by S5.4.2.1(a)(1). The other rear seat is typically allowed to be near or against the rear wall of the bus to fully utilize the available seating floor space and to provide maximum knee clearance. When viewed from the rear, this seat protrudes into the door opening, and according to the (March 24) interpretation ..., the area of the obstruction would not be credited to the exit. Following the logic of the interpretation, the area of the seat itself and the area above the seat could not be credited. We disagree with the logic of the interpretation that door exits are only used by movement along the floor. If the bus is on its side or top, the exit must be used from different approaches. It is therefore our logic and interpretation that only the actual area obstructed (i.e. the area of the seat and the area below the seat) cannot be credited to the exit. For the case in question, the area above the seat can be used in many accident scenarios and therefore can be credited as 'daylight opening.' (See figure 1b) Is this interpretation correct? You are correct that emergency doors will be used by people moving along an interior surface other than the floor if the vehicle is on its side or roof following an accident. As stated in the March 24 interpretation, in determining the amount of daylight opening, you should not credit any area which 'cannot be used for exit purposes.' In the case of the seat illustrated in incoming letter from Wayne, the area over the seat is 6.12 inches by 12.5 inches. However, in reviewing that letter in light of your question, we now agree that the area over the seat may be usable in some accident scenarios. For your exit, neither your letter nor figure 1b provide dimensions of the area over the seat. If the area is large enough to be usable in an accident scenario, that area can be credited towards the daylight opening. c. The rear emergency door on Blue Bird school buses is hinged on the outside, and the top portion of the door is angled forward when the door is closed. When the door is opened and held in the open position by the device required by S5.4.2.1(a)(3)(i), the door protrudes into the exit opening when viewed from a direction perpendicular to the plane of the opening. It is our understanding, based on the interpretation of reference 3, that the protrusion of the door now constitutes an obstruction and the area of the obstruction cannot be credited to the exit area. (See figure 1c) Is this understanding correct? This is correct. Emergency Window Exits The seat backs of school bus seats can protrude into the lower region of side window exit openings. Side window exits when the bus is upright may be used by climbing over the seats. If the bus is on its side or top, the side window exits may be used from different approaches. Since areas of sufficient size above, in front of, and behind a protruding seat back could be used for different parts of the body, (i.e. head, knees, legs) when crawling out a side window exit in different vehicle orientations, it is our logic and interpretation that only the actual area of the seat back in the side window exit opening and the smallest area bounded by the seat back, a horizontal plane tangent to the top of the seat back, and the edges of the exit opening constitute obstructions and cannot be credited to the exit. (See figure 2) Is this interpretation correct? In your illustrations, the area obstructed by the seat back protruding into the window opening clearly cannot be credited to the daylight opening. Whether area above or forward or rearward of the seat back can be credited depends on whether the size of the area is sufficient to be used in exiting the vehicle. Any of these areas which permits passage of the ellipsoid proposed in a December 1, 1993 notice of proposed rulemaking indicates that these areas clearly should be credited (58 FR 63321, see proposed S5.4.2.1(c)). NHTSA proposed this because it believed it reflected the minimum size window which could be used as an exit. If not cut off by obstructions from other unobstructed areas of the daylight opening of the window, as viewed in a plan view, it may be possible that smaller areas should also be credited. In all of the illustrations in figure 2, the seat back extends less than halfway up in the opening. Therefore, it appears that the area above the seat would be credited. We also agree that if the seat protrudes near the front or rear edge of the window opening, it is unlikely that the area between the seat back and the nearest edge of the opening would be usable. However, one of your illustrations shows the seat back protruding near the center of the window opening. In such an instance, it may be possible that the area on each side of the seat back is large enough to be usable. For example, a person might use the window by climbing over the seat, with either their legs straddling the seat, or their head and torso over one side of the seat and their legs over the other. Side Emergency Exit Doors Following the logic presented above regarding the use of emergency exits in different vehicle orientations, we disagree with the interpretation that area A2 (an area bounded by a horizontal line tangent to the top of the seat back, a vertical line tangent to the rearmost portion of the top of the seat, the upper edge of the door opening, and the edge of the door forward of the seat) ... is not usable. In fact even when using the side emergency door when the vehicle is upright, a person would likely lean over the seat back and hold on to the seat, thus using area A2. Figure 3 enclosed is drawn more to scale than the illustration used in (the March 24 interpretation). We suggest the Agency review this illustration, conduct field research by using the exits in real buses, and then reconsider the interpretation ... regarding side emergency doors. We recommend that area A2 be credited as 'daylight opening' for a side emergency door. As explained in our response to question b on rear emergency exit doors, the area above some seats may be large enough to be credited toward the daylight opening. Front Service Door a. The lower portion of the grab handle on many school bus front service doors protrudes into the exit opening when viewed from a direction perpendicular to the plane of the opening. (See figure 4) Based on the (March 24) interpretation ..., we understand that this protrusion now constitutes an obstruction. Is this understanding correct? This is correct. b. The front service door of most school buses leads to a stepwell and steps used to enter the bus. On front engine transit style school buses, the steps are typically angled to the rear and the riser to the first step is just a few inches inboard of the door opening. It is our logic and interpretation that steps in a stepwell do not constitute an obstruction and their presence does not reduce the area credited to the entrance door opening. (See figure 4) Is this interpretation correct? The steps provide the means of using the door, allowing a person to move between the ground and the floor level of the bus. They do not 'block, obscure, or interfere with, in any way, access' of occupants descending to the front service door. Therefore, although they are visible in the doorway when the doorway is viewed in a plan view, the steps are not obstructions within the meaning of the definition of daylight opening. I hope you find this information helpful. If you have any other questions, please contact my staff at this address or by phone at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam0630OpenMr. Robert Waggoner, c/o ABCO Insurance Brokers, P.O. Box 1066, Reseda, CA 91335; Mr. Robert Waggoner c/o ABCO Insurance Brokers P.O. Box 1066 Reseda CA 91335; Dear Mr. Waggoner: This is in reply to your letter of February 16, 1972, requestin information on 'a new law effective January 1, 1972, that makes it mandatory that manufacturers of truck bodies and those repairing such items must now certify their product.'; The National Traffic and Motor Vehicle Safety Act of 1966 (15 U.S.C 1381 *et seq*.) has required since January 1, 1968, that manufacturers of motor vehicles and motor vehicle equipment certify that the products they manufacture comply with all applicable Federal motor vehicle safety standards (49 CFR 571.101 *et seq.). The 'new law' to which you refer is actually regulations issued pursuant to Section 114 of the Act (15 U.S.C. 1403) which amended existing regulations specifying the method by which manufacturers are to certify compliance. These regulations are the Certification regulations (49 CFR Part 567) and the regulations governing 'Vehicles Manufactured in Two or More Stages' (49 CFR Part 568). I have enclosed copies of both for your information.; These regulations apply to manufacturers and distributors of moto vehicles as defined in the regulations. They only apply to manufacturers of truck bodies if such manufacturers install the truck bodies on chassis, thus completing the vehicles. The regulations do not apply to one who only repairs truck bodies.; Yours truly, 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.