Interpretation ID: nht90-3.84

TYPE: Interpretation-NHTSA

DATE: September 7, 1990

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Bob Abernethy -- Idea's Inc.

TITLE: None

ATTACHMT: Attached to letter dated 5-22-90 from B. Abernethy to Office of Chief Council, NHTSA (OCC 4858; OCC 4583); Also attached to Automotive Engineering Magazine editorial, dated July, 1985, entitled "Regulation at its Best?"

TEXT:

This is in reply to your letters of March 21 and May 22, 1990, requesting an interpretation of the Federal standard on motor vehicle lighting, No. 108, as it relates to an invention of yours, and of July 2, 1990, withdrawing a request for confidentiality made in your earlier letter.

As we understand it, based upon your conversation with Mr. Van Iderstine of this agency, your device would make the light emitted from a lamp increase or decrease in intensity based on the level of acceleration or deceleration of the vehicle. Thus, as a vehicle decelerates, the intensity of the lamp would change from a high value to a low value as the vehicle proceeded to stop. You believe that this would discourage tailgaters.

However, the device would also simultaneously modulate in intensity at an unknown rate. The reason that it would do so is that it is sensitive to external forces and is of low inertia. This means that it would also respond to minute changes in decelera tion that occur because of other factors. These factors include uneven road surfaces, uneven brake rotor thickness that causes surging, and tire imbalance which causes vehicle vibrations. Thus, as the intensity changes from a higher to a lower level du ring the stop, it would randomly modulate from a slightly higher intensity to slightly lower and back as the device sensed the random accelerations and decelerations from these other effects. The actual signal resulting would vary from vehicle to vehicl e, and from roadway to roadway as these extraneous factors interacted with the device. A driver following would not see a signal that was consistent or reliable in its meaning.

Therefore, we have concluded that Standard No. 108 would not permit your device. Under the standard, rear lights such as stop lamps and taillamps must be steady burning when in use, and they would not be when your device is employed. Further, equipment not required by Standard No. 108 may not be used if it would impair the effectiveness of the lighting equipment that the standard does require. We believe that your device would impair the distinctive "message" (either as a signal light or as a presenc e light) that each rear lamp is intended to convey.