Interpretation ID: nht93-4.50
DATE: June 28, 1993
FROM: John Womack -- Acting Chief Counsel, U.S. Department of Transportation, NHTSA
TO: Steven Henderson -- Department of Psychology, McGill University
TITLE: None
ATTACHMT: Attached to letter dated 5-26-93 from Steven Henderson to Howard Smolkin (OCC 8732).
TEXT: This responds to your petition of May 26, 1993, to the Acting Administrator for rulemaking to amend Motor Vehicle Safety Standard No. 108 to permit use of your motorcycle "horn-activated headlight/signallight flasher system." As you have described it, pushing the horn button "causes the headlight and signal lights to flash 10 times per second." This matter has been the subject of previous correspondence by this Office, specifically letters to you from Chief Counsel Rice dated June 29, 1992, and August 28, 1992.
As Mr. Rice informed you in his first letter, the operation of your device conflicted with several paragraphs of Standard No. 108. First, the flash rate of 10 cycles per second exceeded the maximum of 280 cycles per minute that is allowed under S5.6.1(a) for modulation of motorcycle headlamps. Second, the taillamps would no longer be steady-burning as required by S5.5.10 (d). Further, it appeared that the turn signal rate would also cease to comply with the flash rate of 60-120 per minute specified by SAE requirements incorporated by reference in Standard No. 108.
You responded on August 11, 1992, that it was improper to consider your device under S5.6 as it is not a motorcycle headlamp modulating system as described in that section. Thus, in your view, our objections to modulation rate and intensity, based upon that section, were misplaced. In his reply of August 28, 1992, Mr. Rice assumed for the sake of argument that your device was not part of a headlamp modulating system subject to S5.6. However, he pointed out that S5.1.3 of Standard No. 108 prohibits installation of equipment that impairs the effectiveness of lighting equipment that Standard No. 108 requires, and that the applicability of that paragraph did not affect his previous comments regarding the noncompliances of the flashing taillamps and the turn signal flash rate. He also commented that the device's flash rate of 10 hz would impair the effectiveness of the required turn signal flash of 1-2 hz, as well as having another undesirable consequence, the triggering of a photic reaction in an observer.
The cover letter to your petition of May 26, 1993, states that the taillamps will now be steady burning. Further, the system has been redesigned so that the turn signal has priority, "so that if the horn button is pressed while a turn is being signalled, the turn signal continues to flash at 2 hz and only the headlamp flickers at the 10 hz rate." Your letter also contains data and arguments indicating that our concern about photic reaction to a 10 hz rate is misplaced. In our view, these modifications and comments have adequately addressed our previous concerns about your system, and no rulemaking is required for its manufacture and sale. For this reason, we see no need for further agency action upon your petition. However, the amendments you have asked for differ in some respects from the redesigned system you have described
(e.g., that both the turn signals and the headlamp be permitted to flash at 10 hz). If you wish to go forward with the redesigned system without an amendment to Standard No. 108, we ask that you withdraw your petition. On the other hand, if you wish us to go forward with consideration of your petition, please inform us.
Your most recent letter raised one further question with regard to S5.1.3, that is, whether the operation of the headlamp at 10 hz impairs the effectiveness of a turn signal operated at 2 hz. We have noted that S5.6 permits simultaneous operation of a turn signal and a headlamp modulating in the range of 6 hz, and have concluded that the difference in flash rate ought not to impair the turn signal function.
Finally, we would like to advise you that usage of the system in the United States is governed by the laws of any State in which the system is operated, and not by any Federal regulation. We are unable to advise you as to the permissibility of use of your system under State laws, and suggest that you contact the American Association of Motor Vehicle Administrators, 4600 Wilson Boulevard, Arlington, Va. 22203, for an opinion.