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: aiam5054OpenMr. J. W. Lawrence Manager, Compliance and Technical Legislation Volvo GM Heavy Truck Corporation P.O. Box 26115 Greensboro, NC 27402-6115; Mr. J. W. Lawrence Manager Compliance and Technical Legislation Volvo GM Heavy Truck Corporation P.O. Box 26115 Greensboro NC 27402-6115; Dear Mr. Lawrence: This responds to your March 5, 1992 letter to th Administrator on the subject 'Petition for Rulemaking - FMVSS 108 Turn Signal Installation Requirements.' In that letter, Volvo GM petitioned 'for the revocation of the 'Figure 2' requirements published in the December 12, 1991, Register. . . .' However, the notice published on that date (56 FR 64733) was not an amendment of Federal Motor Vehicle Safety Standard No. 108. Instead, it was only a denial of a petition for rulemaking to allow tail lamps on vehicles 80 inches or wider to be mounted at locations up to 24 inches forward of the extreme rear of the vehicle, and to allow turn signal and stop lamps to be mounted up to 60 inches forward of the rear instead of 'on the rear' as required by Standard No. 108. Paragraph S5.3.1.1 of Standard No. 108 expresses the general requirement that lamps be located so as to meet the visibility requirements specified in any applicable SAE standard. Figure 2 was included in the notice to illustrate the agency's interpretation of the visibility requirements for stop, tail, and turn signal lamps set forth in specific SAE vehicle lighting standards incorporated by reference in Standard No. 108. A copy of that figure is enclosed. However, Figure 2 is not incorporated into Standard No. 108 itself. Since Figure 2 is not part of Standard No. 108, a petition for rulemaking is not the appropriate way to address the problem you have raised. Accordingly, we are treating your letter as a request to change our interpretation of the SAE's specifications. As explained below, the agency is adopting a new interpretation that is consistent with your concerns and arguments. The rationale for the agency's denial of the petition was that the amendments requested would adversely affect the ability of the lamps to meet the SAE specifications incorporated into Standard No. 108 that the lamps on both sides of a vehicle's rear end be simultaneously visible from any angle between and including 45-degree angles to the rear left and right of the vehicle. As noted above, Figure 2 pictorially represents NHTSA's interpretation of the SAE's uniform geometric visibility requirements. Using the SAE standard for turn signal lamps on wide vehicles as an example, NHTSA provided the following quotation from J1395: 'Signals from lamps on both sides of the vehicle shall be visible through a horizontal angle from 45 deg. to the left for the left lamp to 45 deg. to the right for the right lamp. * * * To be considered visible, the lamp must provide an unobstructed view of the outer lens surface, excluding reflex of at least 13 sq. cm. measured at 45 deg. to the longitudinal axis of the vehicle.' Since the SAE measurement of photometry is made at a distance of 3 meters from the lamp, NHTSA also stated that compliance with the visibility requirements is to be determined at a distance of 3 meters. NHTSA's interpretation of the SAE language quoted above, which Figure 2 illustrates, and which you have found objectionable, was: 'Thus, the turn signals on both sides of the vehicle must be simultaneously visible through a horizontal angle from 45 degrees originating at the left lamp, to the left to 45 degrees to the right originating at the right lamp measured at a radius of 3 meters.' You state that the term 'simultaneously visible' does not appear in the SAE specifications. You also argue that the 3 meter requirement has no connection to the 45-degree installation visibility. These issues have also been raised with us by the Motor Vehicle Manufacturers Association (MVMA), which met with us to express its views, not only on turn signal lamps, but stop and tail lamps as well, and by Ford Motor Company, and Freightliner, Corp. in several telephone calls. We are furnishing copies of this response to these three parties, as well as to the original petitioner, Truck Trailer Manufacturers Association (TTMA). First of all, let me assure you that NHTSA had no intention of imposing any new requirements upon industry in its interpretation reflected in Figure 2, and that the reaction of industry to this interpretation came as a surprise to us. Although your letter concerns only the turn signal specifications for wide vehicles, we have reviewed this matter with respect to tail lamps and stop lamps as well, given the concern of other industry members. Our review has led us to place added weight on the fact that the SAE visibility requirements are not consistently expressed from SAE standard to SAE standard. This difference in expression particularly calls into question our interpretation regarding turn signals. This same difference has led MVMA to apply one interpretation to turn signals, and another to stop and tail lamps. We shall discuss these two interpretations separately, and compare them with NHTSA's single, across-the-board interpretation. Under NHTSA's interpretation, the minimum specified lens area of a left stop, turn signal, or tail lamp, as seen at 45 degrees to the left of that lamp, must also be seen at 45 degrees to the right of the right lamp, and at all degrees in between (and vice versa) when viewed at a 3-meter radius from the rear. As suggested above, MVMA does not believe that an across-the-board interpretation is appropriate, given the different expression of the turn signal specification for vehicles in J1395 and J588. SAE J1395 provides that visibility is 'from 45 deg. to the left for the left lamp to 45 deg. to the right for the right lamp.' (Emphasis added.) The first underlined passage suggests that the viewing angle is a left 45 deg. angle, using a line parallel to the vehicle longitudinal axis as the frame of reference for that angle, and that this viewing angle relates to the left signal lamp only. The passage says that the angle is 45 deg. to the left 'for' the left lamp, and not 45 deg. to the left of that lamp. The second underlined passage indicates a similar limitation on the applicability of the language regarding the 45 deg. angle to the right. Even more specific is the corresponding requirement in SAE J588 NOV84, Standard No. 108's specification for turn signals on vehicles less than 80 inches wide. It provides: 'signals from lamps mounted on the left side of the vehicle shall be visible through a horizontal angle of 45 deg. to the left and signals from lamps mounted on the right side of the vehicle shall be visible through a horizontal angle of 45 deg. to the right.' For both wide and narrow vehicles, MVMA interprets the 45 degree left visibility requirement as applying only to the outboard side of the left turn signal lamp, and a 45 degree right visibility requirement only to the outboard side of the right turn signal lamp. NHTSA agrees that MVMA's interpretation regarding turn signal lamps is more fully consistent than NHTSA's interpretation with the language of these SAE standards. Adopting this interpretation moots the question of the particular distance at which visibility is to be determined. However, the fact that the SAE standard did not specify a measurement distance tends to strengthen the case for the MVMA interpretation since its interpretation obviates the need for a measurement distance, while the former NHTSA interpretation necessitated one. The MVMA and TTMA interpretations of the stop and tail lamp requirements are less clearly superior to NHTSA's in their faithfulness to the language of the SAE standards. Indeed, whether any of the competing interpretations is superior in this regard is harder to assess because the language regarding these lamps is more ambiguous. The SAE specifications for stop and tail lamps, incorporated in Standard No. 108, are respectively J586 FEB84 (narrow vehicles) and J1398 MAY85 (wide vehicles), and J585e Sept. 1977. Under all three of these SAE standards, 'signals from lamps on both sides of the vehicle shall be visible through a horizontal angle', which is specified as 'of 45 deg. to the left and to 45 deg. to the right' (J586), 'of 45 deg. to the left to 45 deg. to the right' (J1398), and 'from 45 deg. to the left to 45 deg. to the right' (J585e). TTMA and MVMA restrict the left-right 45 degree visibility requirement to the individual lamp in a horizontal plane, as shown in Figure 1 of the December 1991 notice. Under this interpretation, the minimum specified lens area that is seen at 45 degrees to the left on the left lamp must be seen at 45 degrees to the right of the left lamp, but need not be seen at 45 degrees to the right of the right lamp (and vice versa). In MVMA's view, there was never an intent by the SAE to expect that the minimum lens area of both lamps would be visible from both sides of the vehicle. MVMA also argued that there was no justification to use the photometric measuring distance of 3 meters to determine visibility. Some aspects of the SAE standards regarding stop and tail lamps seem to favor the MVMA/TTMA interpretation, while others favor the NHTSA interpretation. For example, if these SAE standards are interpreted in light of the interpretation given above to the SAE turn signal requirements, then those stop and tail lamp standards will be interpreted as specifying angles of visibility whose frame of reference is each individual lamp instead of the vehicle as a whole. As in the case of the turn signal requirement, the absence of a specified measurement distance for stop and tail lamp visibility tends to support an interpretation that does not depend on such a distance being specified. On the other hand, the absence of any language, like that found in J1395, relating the angle or angles of visibility to any individual lamp, suggests a single continuous horizontal angle spanning the entire rear of a vehicle. NHTSA has decided to adopt the TTMA/MVMA interpretation of the stop and tail lamp visibility requirements. We have said that NHTSA did not intend to impose new burdens on industry by its interpretation, and there appears to be no present safety justification to do so. The existing level of rear lighting safety on the nation's roads is that which is represented by industry's interpretation of the SAE visibility requirements. Thus, there would be no derogation of the existing level of safety by concurring with an industry interpretation. Further, given the lack of clear support for either of the competing interpretations, any attempt by NHTSA to apply its former interpretation to enforce these requirements in a court of law could be very problematic. This letter will serve as notice to the industry that the agency will follow the interpretations stated herein in its future enforcement activities. The SAE visibility materials do not specify any measurement distance. Therefore, to carry the new interpretation to its proper conclusion, NHTSA is no longer specifying a measurement distance of 3 meters to judge compliance with the visibility requirements. Industry and NHTSA are both in agreement, however, that, wherever located, any of these lamps are required by S5.3.1.1 to continue to meet its photometric output at any applicable group of test points, unless excepted by the subsequent conditions of that paragraph. Finally, you comment that Table II 'does not require the turn signals be located on the rear except for trailers'. We do not understand your remark since Table II clearly specifies that turn signal lamps be located on the rear of all vehicles to which the Table applies, and not trailers alone. Sincerely, Paul Jackson Rice Chief Counsel Enclosure cc: Motor Vehicle Manufacturers Association Truck Trailer Manufacturers Association Ford Motor Company Freightliner Corp.; |
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ID: aiam4096OpenMs. Karen Finkel, Executive Director, National School Transportation Association, P.O. Box 2693, Springfield, VA 22152; Ms. Karen Finkel Executive Director National School Transportation Association P.O. Box 2693 Springfield VA 22152; Dear Ms. Finkel: This responds to your March 3, 1986 letter to our office concernin requirements applicable to front seat restraining barriers on school buses. You asked whether the barriers meet the same Federal motor vehicle safety standards as the school bus seats. Specifically, you are interested in barrier-seat separation and barrier performance requirements.; Federal Motor Vehicle Safety Standard No. 222, *School Bus Passenge Seating and Crash Protection*, establishes requirements for school bus seats and restraining barriers. Included in Standard No. 222 are paragraphs S5.2 through S5.2.3 which specifically apply to restraining barriers on school buses with gross vehicle weight ratings over 10,000 pounds. Since restraining barriers function to compartmentalize passengers in the same manner as school bus seats, the requirements of Standard No. 222 for barrier-seat separation distances and barrier strength are similar to the spacing and strength requirements for school bus seats. For example, S5.2.1 specifies that the distance between a restraining barrier's rear surface and the seating reference point of the first seat to the rear of the barrier must not be more than 24 inches. Also, under S5.2.3, barriers are tested for compliance with the forward performance requirements in the same manner as school bus seats. Both must withstand similar forces while maintaining component integrity. Force/deflection curves for seat backs and restraining barriers must fall within the zone specified in Figure 1 of Standard No. 222, and seat back and restraining barrier deflection must not exceed 14 inches. Further, restraining barriers and seat backs must meet the same impact zone requirements (S5.3) of the standard. Additional requirements for restraining barriers are specified in Standard No. 222. A copy of the standard is enclosed for your convenience.; You asked whether the front seat barrier is secured to the floor of th school bus in a different manner than the seats. Standard No. 222 does not specify how school bus restraining barriers or seats are to be secured to the floor of the bus. Manufacturers are free to select the manner of securing barriers and seats to the bus floor as long as those structures meet all applicable requirements of our safety standards.; I hope this information is helpful. Please contact our office if we ca be of further assistance.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam3753OpenMr. Karl-Heinz Ziwicka, Manager, Safety & Emission Control Engineering, BMW of North America, Inc., Montvale, NJ 07645; Mr. Karl-Heinz Ziwicka Manager Safety & Emission Control Engineering BMW of North America Inc. Montvale NJ 07645; Dear Mr. Ziwicka: This is in reply to your letter of August 15, 1983, asking for a interpretation of Federal Motor Vehicle Safety Standard No. 108 with respect to spacing of turn signal lamps on motorcycles.; As you have noted, SAE Standard J588e is the basic Federal requiremen for turn signal lamps referenced by Tables I and III of Standard No. 108 for all motor vehicles. One of the requirements of J588e is that the front turn signal must be separated from the low beam headlamp by at least 4 inches measured from the filament center of the turn signal to the inside diameter of the retaining ring of the low beam headlamp. But, as you further point out, paragraph S4.3.1.7 of Standard No. 108 relieves this restriction under certain circumstances. However, because Table IV of Standard No. 108 specifically requires a minimum edge to edge separation distance of 4 inches between the turn signal lamp and the headlamp on a motorcycle, you believe that it is unclear whether S4.3.1.7 relieves this restriction also, and have asked us for an interpretation that it does.; We are unable to provide the interpretation that you seek. True, SA J588e does incorporate a spacing restriction which is relieved by S4.3.1.7 under certain circumstances. However, although the requirements of J588e generally do apply to motorcycle turn signal lamps, the spacing restriction does not apply, having been superseded by the specific language in Table IV addressed to motorcycles. We believe that it is important to maintain a minimum edge to edge distance on motorcycles that exceeds the minimum allowable on other motor vehicles, in order to assure that the conspicuity of the turn signal will not be masked by the headlamp beam. Because the motorcycle headlamp beam is not fixed in relation to the road as an automobile headlamp is, its vertical and horizontal aim will change with the lean angle and the steering angle of the machine. The higher intensity portions of the beam will rise above the horizontal, thus producing more glare and reducing the conspicuity of the turn signal. Further, given the almost universal daytime use of headlamps, the lesser conspicuity of the turn signal on motorcycles during daylight hours must not be compromised.; I hope that this answers your question. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam2841OpenMr. Robert Hoppe, 1436 So. Sherman Street, Longmont, CO 80501; Mr. Robert Hoppe 1436 So. Sherman Street Longmont CO 80501; Dear Mr. Hoppe: This responds to your letter of May 3, 1978, in which you request determination as to whether the three- wheeled motor vehicle which you are designing is a 'motorcycle' or an automobile ('passenger car') for purposes of complying with federal motor vehicle safety standards.; The vehicle falls within the definition of 'motorcycle' set forth i regulations under the National Traffic and Motor Vehicle Safety Act of 1966:; >>>'Motorcycle' means a motor vehicle with motive power having a sea or saddle for the use of the rider and designed to travel on not more than three wheels in contact with the ground. (49 CFR Part 571.3(b))<<<; Accordingly, the vehicle would have to meet the requirements of safet standards applicable to motorcycles. I have enclosed an information sheet explaining where you can obtain federal standards and regulations.; I want to point out that in April 1974, this agency proposed a revisio of the above definition of 'motorcycle' under which this term would be limited to two-wheeled motor vehicles and to three-wheeled motor vehicles with handlebars and no passenger enclosures. I have enclosed a copy of this proposal. However, in view of the time that has elapsed since the proposal was issued, the agency has decided not to issue a final rule on this subject without providing another opportunity to comment.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam1294OpenL.E. Haight, Esq., Attorney at Law, 805 Idaho Street, P.O. Box 2777, Boise, ID 83701; L.E. Haight Esq. Attorney at Law 805 Idaho Street P.O. Box 2777 Boise ID 83701; Dear Mr. Haight: This is in reply to your letter of September 21, 1973, concerning you desire to disconnect the interlock system on your new car.; The dealer who sold you the car was required to have the interloc working at the time of sale pursuant to section 108(a)(1) of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1397(a)(1)). However, section 108(b)(1) of the Act (15 U.S.C. 1397(b)(1)), provides that the requirements of 108(a)(1) do not apply after the first purchase of the vehicle for purposes other than resale. As a purchaser who intends to use the vehicle, you are therefore not subject to the requirements of the Act and may disconnect the interlock.; Despite the absence of legal sanctions for disconnecting the interlock we would hope that you could find a way to adjust the belt so that it could be worn without aggravating your bursitis. The physical sanctions for an unbelted person in a crash can be serious indeed.; Sincerely, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3303OpenMr. Thomas P. McAskin, Kelsey-Hayes Company, Romulus, MI 48174; Mr. Thomas P. McAskin Kelsey-Hayes Company Romulus MI 48174; Dear Mr. McAskin: This responds to your December 7, 1979 letter to Docket No. 79-03 Notice 2 on Heavy Duty Vehicle Brake Systems. That letter was in part a comment to the docket and in part a request for an interpretation of Standard No. 121, *Air Brake Systems*. The points raised in your comment to the docket will be considered in our final rule on the issues proposed in Notice 2. This letter responds to your interpretive question whether your trailer emergency valve is permitted in accordance with the requirements of section 5.2.1.1 of the standard. The answer to your question is no.; Section 5.2.1.1 of the standard requires that vehicles be equipped wit a reservoir that is capable of releasing the parking brakes when the air in the service brake system fails. The valve that you suggest would not provide such a reservoir but would merely reroute air from the trailer air supply system which would be used to release the parking brakes. The agency does not believe that this complies with the requirement that a reservoir be provided.; Recently, the Berg Manufacturing Company has petitioned the agency t amend the standard in a manner that would permit the type of system that you suggest. The agency is now evaluating that petition and will issue a notice in the near future addressing this issue. We suggest that you closely follow this rulemaking action.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam2142OpenInterps. file, Parts 575.104(d)(1)(ii) and 575.6; Interps. file Parts 575.104(d)(1)(ii) and 575.6; Office visit by Pat Raher, Hogan and Hartson I received an office visit on December 8, 1975, from Mr. Raher of Hoga and Hartson (representing Mercedes-Benz). He showed me a sample information sheet of the type that Mercedes proposes to use to indicate the quality grades of tires with which its vehicles are equipped. We discussed the vehicle manufacturer's information requirement of the Uniform Tire Quality Grading Standards, and I indicated that a formal interpretation would follow our receipt of his letter, which is en route.; Mark I. Schwimmer, Attorney- Advisor |
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ID: aiam4995OpenMr. Gonshiro Miyoshi Manager, Design Administration Dept. Technical Division Ichikoh Industries, Inc. 80 Itado, Isehara-City Kanagawa, 259-11 Japan; Mr. Gonshiro Miyoshi Manager Design Administration Dept. Technical Division Ichikoh Industries Inc. 80 Itado Isehara-City Kanagawa 259-11 Japan; Dear Mr. Miyoshi: This responds to your letter of April 6, 1992, askin for an interpretation of Standard No. 108. With respect to a headlamp system consisting of two lamps, each containing two light sources, you have asked 'Is it permissible to have the bulb center of the lower beam lower than that of the upper beam (maximum height difference is 10mm) if they are arranged horizontally?' Paragraph S7.5(d)(2) specifies the manner in which 'the lower and upper beams of a headlamp system consisting of two lamps, each containing either one or two light sources, shall be provided . . .' In such headlamps where each light source provides a beam, the lower beam is provided 'by the outboard light source (or upper one if arranged vertically),' and the upper beam is provided 'by the inboard light source (or the lower one if arranged vertically).' Although the standard could be presumed to contemplate that two light sources within a headlamp would be located on the same horizontal or vertical plane, there is no specific requirement for light source placement. Because the difference in the horizontal mounting planes for bulb centers in your design is only 10mm, this difference is not sufficient to conclude that the light sources are vertically arranged, thus requiring that the lower beam bulb center be the 'upper' one, or on a plane that is higher. However, for your design to be permissible, the lower beam in this essentially horizontal array must be provided by the outboard light source in the headlamps as specified in S7.5(d)(2). Sincerely, Paul Jackson Rice Chief Counsel; |
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ID: aiam0485OpenMr. E. M. Ryan, Chief Design Engineer, Ward School Bus Mfg., Inc., P. O. Box 849, Conway, AR, 72032; Mr. E. M. Ryan Chief Design Engineer Ward School Bus Mfg. Inc. P. O. Box 849 Conway AR 72032; Dear Mr. Ryan: Your letter of October 28, 1971, to Mr. Stan Haranski, Truck Body an Equipment Association, Inc., concerning switching arrangements for school bus red signal lamps, has been forwarded to this Office for reply.; Paragraph S4.1.4(a) of Federal Motor Vehicle Safety Standard No. 10 requires that the four red signal lamps be controlled by a manually actuated switch. A two-way switch, whereby all four lamps are activated when the switch is in one position, and the two rear lamps only are activated when the switch is in the opposite position, would not be in violation of this requirement of Standard No. 108.; Sincerely, E. T. Driver, Director, Office of Operating Systems, Moto Vehicle Programs; |
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ID: aiam2512OpenMr. Raymond Titsworth, Project Engineer, Ward School Bus Mfg., Inc., P. O. Box 849, Highway 65 South, Conway, AR 72032; Mr. Raymond Titsworth Project Engineer Ward School Bus Mfg. Inc. P. O. Box 849 Highway 65 South Conway AR 72032; Dear Mr. Titsworth: This responds to your December 7, 1976 and January 8, 1977, question whether 53 described intersections of bus body components qualify as 'body panel joints' subject to the requirements of Standard No. 221, *School Bus Body Joint Strength*. This also responds to your question whether the seating reference point in Standard No. 222, *School Bus Passenger Seating and Crash Protection*, can be located using nominal seat cushion deflection.; The terms which establish the applicability of the requirements of th standard to a particular section of a school bus body are defined in S4 of the standard. Read together, they establish the following test. If the edge of a surface component (made of homogeneous material) in a bus that encloses the bus' occupant space comes into contact or close proximity with any other body component, the requirements of S5 apply, unless the area in question is designed for ventilation or another functional purpose or is a door, window, or maintenance access panel. Applying this test to the 53 intersections of bus body components you describe, it appears that the areas corresponding to the following numbered paragraphs of your letter are bus body joints and therefore must meet the 60-percent joint strength requirements: 1 through 34, 36, 37, 39, 42, 44, 45, 46, 51. Additionally the joint described in your January 8, 1977, submission must comply with the standard.; The illustration accompanying paragraph 16 shows a second joint betwee a door post and exterior trim panel with the notation that this joint is 'Not Required To Meet Std.' The agency concludes that this joint also must meet the requirements of the standard, because it is a connection of a body component with a body panel that encloses occupant space.; The lower skirt section described in paragraph 35 is not a body pane that encloses occupant space, because it is located entirely below the level of the floor line and, therefore, is excluded from the standard's requirements.; In the control console area, the interior side panel described i paragraph 38 and the shoulder cap (wire cover) described in paragraph 43 are considered maintenance access panels, whose joining with the bus body is excluded from the requirements only if a wire is installed behind them.; The turn signal housings described in paragraphs 40 and 41 are no considered to have a function in enclosing the occupant space and are therefore not considered body components for purposes of the requirements.; The front and rear headers described in paragraphs 47 and 48 ar considered primarily structural and have only an incidental role in enclosing the occupant space and, therefore, are not considered 'body panels' for purposes of the requirements.; The rubrail described in paragraph 49 is not considered to have function in enclosing the occupant space and, therefore, is not considered a body component for purposes of the requirements. For purposes of testing the complex joints to which it is fastened, it should be modified as necessary to prevent it from affecting testing of the underlying joint.; Because the plywood described in paragraph 50 is attached to a floo panel and is only added to some buses for insulation purposes, it is not considered to have a function in enclosing the occupant space and is therefore not considered a body component for purposes of the requirements.; The NHTSA concludes that parts A, E, and F of paragraph 52 describ joints between maintenance access panels and the bus body. The heater ducts in parts B, C, and D are the type of ventilation space that is not subject to requirements for joint strength.; In response to your question concerning the effect of seat cushio deflection on the location of the seating reference point, the NHTSA has determined that the definition of seating reference point contemplates some deflection of seat cushions to simulate compression of padding material under the weight of a human torso and thigh. As noted in the preamble of the second proposal for a school bus seating standard (39 FR 27585, July 30, 1974), 'It can be seen that the manufacturer's freedom to locate the point is sharply restricted by the definition which specifies that it actually simulate the position of the pivot center of the human torso and thigh, following SAE placement procedures.' However, since the seating reference point is an approximation of the pivot center, the NHTSA permits the manufacturer to locate the point based upon nominal seat cushion deflection.; Sincerely, Frank A. Berndt, Acting 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.