Interpretation ID: aiam5054
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.;