Interpretation ID: nht92-4.23

DATE: August 28, 1992

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Steven Henderson -- Department of Psychology, McGill University

TITLE: None

ATTACHMT: Attached to letter dated 8/11/92 from Steven Henderson to Paul Jackson Rice (OCC-7640)

TEXT:

This responds to your letter of August 11, 1992, commenting on my response to you of June 29 with respect to the relationship of your motorcycle headlamp warning device to S5.6 of Federal Motor Vehicle Safety Standard No. 108, the provisions regulating the modulation of motorcycle headlighting systems.

In my letter, I informed you that the device would not comply with the requirements of Standard No. 108, and would affect compliance of the taillamps and turn signal lamps with the standard. I also advised you that if a motorcycle owner could install the device, there would be no violation of Federal law, and that the legality of its use would be determinable under the laws of the individual American states.

In your latest letter, you "agree that the device contravenes the letter of DOT Standard No. 108 as it presently stands." However, "if the device violates the letter of the law while satisfying the spirit or inferred intent of the law in each case," you believe "that the granting of an exception should be considered by the NHTSA."

As I understand it, your principal argument as raised on page 2 of your August 11 letter is that it is improper to consider your device under S5.6 as it is not a motorcycle headlamp modulating system as described in that section. Thus our objections to modulation rate and intensity, based upon the specifications of that section, are misplaced.

Assuming for the sake of argument that you are correct, your device becomes subject to another provision of Standard No. 108 that I did not mention in my June letter. Paragraph S5.1.3 prohibits the installation, as original equipment, of any motor vehicle equipment that impairs the effectiveness of lighting equipment that Standard No. 108 requires. Application of paragraph S5.1.3 returns us to my comments in June that your device would affect compliance of the taillamps and turn signal lamps with Standard No. 108. The taillamps would no longer be steady-burning, as required by S5.5.10(d). It would appear 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. Thus, under paragraph S5.1.3, installation of the device as aftermarket equipment, if performed by a manufacturer, dealer, distributor, or motor vehicle repair business would continue to be prohibited by Federal law.

Your latest letter also addresses the issues of taillamp and turn signal conformance. You argue that

"a taillight's purpose is to mark the rear of a motor vehicle during

nighttime driving when it would otherwise be invisible. For this reason the law requires that taillights be lit at night. The law makes no such requirement during the day. The law does require that motorcycle headlights be lit during the day. *** At night the taillight will always be steady- burning as required by S5.5.10(d) because the flasher device is only able to induce taillight flicker during daylight hours due to the photocell circuitry incorporated to prevent the headlamp from generating strobe effects at night. Therefore, the device is in compliance with S5.5.10(d) as it will cause the taillight to flash only at times that it is not required by law to be lit."

The law that applies to your argument is Standard No. 108. Paragraph S5.5.7(b) states in pertinent part that "On each...motorcycle...when the headlamps are activated in a steady-burning state, the taillamps...shall also be activated." Thus, under Standard No. 108 the taillamps must always be activated when the headlamps are activated.

The device also functions through the horn button to cause the turn signal lamps to flash at a rate higher than the maximum permitted by Standard No. 108. In your view, the situation in which the turn signal and horn button are in simultaneous use will be rare. However, if they are used together, "the SAE-specified turn signal flash of 1-2 hz will be perceptually present, the hazard signal flash of 10 hz will also be perceptually present at the same location, and the two signals will not interfere."

We consider that paragraph S5.1.3 applies here as well, and that a flash of 10 hz would impair the effectiveness of the required turn signal flash of 1-2 hz. There could be another undesirable consequence as well. When NHTSA proposed allowing modulating headlamps, commenters were concerned that the flashing might trigger a photic reaction, akin to an attack of epilepsy, in onlookers. NHTSA observed that the reaction was most likely to occur at a frequency of 10 hz against a very dark background. Although your device does not operate at night, its frequency is at the threshold where photic reactions can occur, and we want to bring this fact to your attention.

The agency shares your concern with improving the detectability of motorcycles and their riders. You have suggested writing an "exception" in Standard No. 108 for a period of one or two years so that the safety benefits of the device can be evaluated. We have a procedure under which a manufacturer of motorcycles can petition for a temporary exemption of up to two years, applicable to 2,500 vehicles per year, on the basis that it would facilitate the development and field evaluation of an innovative safety device. Perhaps you can interest a manufacturer in petitioning for a temporary exemption from Standard No. 108 on this basis.

You may also petition the agency for rulemaking to amend Standard No. 108 in a manner that would allow your device. A petition must set forth facts which it is claimed establish that a change in the standard is necessary, and a brief description of the changes which should be made. This means that you should show how your device is expected to improve safety, or, at a minimum, not decrease the existing level of safety. The agency has no plans to initiate rulemaking on its own initiative to permit your device.