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Interpretation ID: Hyodo.B-3

    Mr. Kiminori Hyodo
    Deputy General Manager, Regulations & Certification
    Koito Manufacturing Co., Ltd.
    4-8-3, Takanawa
    Minato-ku Tokyo
    Japan


    Dear Mr. Hyodo:

    This responds to your letter, in which you sought clarification under Federal Motor Vehicle Safety Standard (FMVSS) No. 108, Lamps, Reflective Devices, and Associated Equipment, as to the location of the axis of reference for a headlamp that incorporates a bending light function. Specifically, you asked about the location of the axis of reference for a bending light mechanism where a portion of the nominal beam pattern is actively redirected to provide illumination in a turn. The issues raised by your letter are addressed below.

    By way of background, the National Highway Traffic Safety Administration (NHTSA) is authorized to issue FMVSSs that set performance requirements for new motor vehicles and items of motor vehicle equipment. FMVSS No. 108 sets forth the requirements for both original equipment and aftermarket lamps, reflective devices, and associated equipment for use on motor vehicles covered under the standard. NHTSA does not provide approval of motor vehicles or motor vehicle equipment. Instead, it is the responsibility of manufacturers to self-certify that their products conform to all applicable safety standards that are in effect on the date of manufacture (see 49 U.S.C. 30115 and 49 CFR Part 567, Certification).

    Regarding the requirements for a headlamp with a bending light function, this topic was addressed in a Request for Comments published in the Federal Register on February 12, 200. (see 68 FR 7101). In that document, we explained that under FMVSS No. 108, "the bending light performance (by automatically reaiming the lamp) is not prohibited because the Standard does not specifically address the initial or subsequent aim of a headlamp in a headlighting system.. 68 FR at 7102. We noted that in a July 21, 1999 interpretation letter to Mr. Mark Cronmiller, VDO North America, we stated that if a "smart" headlamp system meets the static aiming hardware requirements of FMVSS No. 108, a dynamic aiming feature is permissible.

    After discussing our July 1999 interpretation, we included the following paragraph in our document in the Federal Register:

    We note that S5.3.1.1 of Standard No. 108 also requires that lamps and reflective devices must be installed such that their photometric requirements are met on motor vehicles and that no other part of the vehicle shall prevent that. As such, the additional hardware added to achieve AFS must not prevent headlamps, or any other required lamps, from meeting the required performance in any manner whether AFS is operating or not. Additionally, for the bending light mechanization where some of the light in the nominal beam pattern is actively redirected, the photometric requirements of the headlamp must be met regardless of active changes in the light distribution within the beam. 68 FR at 7102.

    In your letter, you asked about the last sentence of the foregoing paragraph. You stated that for bending light mechanization where some of the light in the nominal beam pattern is actively redirected, "NHTSA clarified its legality that the photometric requirements must be met regardless of the active changes in the light distribution within the beam pattern . . . but did not address the location of the axis of reference for the determination of photometric compliance.. You stated that for this type of system, when the optical axis (kink) of the lower beam headlamp moves due to the swivel of an adaptive beam contributor that is utilized with a non-swiveling base beam, you must compensate the goniometer to locate the axis of reference to H = 0 degree / V = 0 degree for that determination.

    Your letter stated further:

    We construe that the goniometer must be compensated because the docket explicitly allows the swiveling of the beam pattern and further requires compliance to the FMVSS 108 lower beam photometric requirement in all the situations throughout the activation of the bending light function. In light of these requirements, in a system where some of the light in the nominal beam pattern is actively redirected and the optical axis (kink) moves due to the changes in the vehicles steering angles, photometry should be done in the direction where the optical axis (kink) of the headlamp is actually directed. This results in exactly the same situation as required for the category 1 bending light mechanization (i.e. swiveling of the whole beam pattern) where a lower beam headlamp meeting the photometric requirements of FMVSS 108 is allowed to be directed toward the direction of the vehicles steering. Also, the direction coincides with the drivers gaze direction when negotiating curves, which is consecutive to the original purpose of the bending light function and significant for the improvement of safety.

    As part of reviewing your letter, we analyzed the paragraph in our February 2003 notice that you asked about. We note that the paragraph construed the language of S5.3.1.1 of FMVSS No. 108 as it existed at that time. Subsequently, we amended that portion of the standar. (see 69 FR 48805, 48813 (August 11, 2004)). The standard no longer includes the former language of S5.3.1.1 that "no part of the vehicle" shall prevent lamps from meeting photometric requirements. Instead, the standard now states at S5.3.2(a) that lamps and reflective devices must be installed in a location where they comply with all applicable photometric requirements and visibility requirements with all "obstructions" on the vehicle.

    We note that in making this change, the agency explained that it was clarifying the sentence and moving it, without making any substantive changes. Thus, in the August 2004 notice, the agency viewed the superseded S5.3.1.1 requirement that no part of the vehicle prevent lamps from meeting photometric requirements as referring to obstructions, a more narrow view than it took in the February 2003 notice. In retrospect, and after reviewing the relevant language and comparing how the agency viewed it in the February 2003 and August 2004 notices, we believe the more narrow reading was correct.

    In any event, the language of S5.3.1.1 construed in the paragraph you asked about is no longer in FMVSS No. 108. That paragraph is not a correct explanation of the standards requirements today and should be disregarded.

    As to what is required for the design you asked about, and similar to the situation where the entire headlamp is reaimed, the standards photometry requirements must be met in the nominal position of the lower beam headlamp (i.e., considering the location of the axis of reference to coincide with the longitudinal axis of the vehicle).

    As defined under S4 of FMVSS No. 108, "axis of reference" means "the characteristic axis of the lamp for use as the direction of reference (H=0, V=0) for angles of field for photometric measurements and for installing the lamp on the vehicle.. In the case of a visually/optically aimable headlamp, for example, the agency would orient the axis of reference through the headlamp optical axis marks. These marks are required by S7.8.5.3(f)(1) to establish the horizontal and vertical alignment of the headlamp, aiming screen, and goniometer, relative to the longitudinal axis of the vehicle. Furthermore, SAE J575 DEC88, as incorporated by reference into FMVSS No. 108, specifies that the vertical axis of the test sample be vertical and perpendicular to the longitudinal axis of the vehicle when mounted on the goniometer, and that the intersection of the H and V planes (a.k.a. axis of reference) be parallel to the longitudinal axis of the vehicle. Once the nominal aim was established, photometry testing would be conducted. FMVSS No. 108 does not require that photometric requirements be met for other axes of reference.

    We note that the photometry requirements of FMVSS No. 108 are intended both to ensure adequate illumination of the roadway and overhead signs and to avoid unnecessary glare to other drivers. While, as discussed above, the standard does not include photometric test requirements for a headlamp with a bending light function other than for the nominal position of the lower beam headlamp, we encourage manufacturers to carefully consider accommodating both of these goals as they design headlamp systems incorporating this new technology.

    I hope this information is helpful. If you have further questions, please feel free to contact Eric Stas of my staff at this address or by telephone at (202) 366-2992.

    Sincerely,

    Stephen P. Wood
    Acting Chief Counsel

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