Interpretation ID: nht90-1.81

TYPE: INTERPRETATION-NHTSA

DATE: 03/22/90

FROM: STEPHEN P. WOOD -- ACTING CHIEF COUNSEL, NHTSA

TO: KENT D. SMITH

TITLE: NONE

ATTACHMT: LETTER DATED 1-26-90 TO OFFICE OF CHIEF COUNCIL, NHTSA, FROM KENT D. SMITH, ATTACHED; [OCC-4387]

TEXT: This is in reply to your letter of January 26, 1990, to the agency with respect to a safety lighting device. You have asked for our recommendations regarding this invention.

The problem addressed by your invention is "that vehicles need some way of signaling following drivers if the headlamps of their vehicles are blinding you." Your solution is to install a button that activates the backup lamps and extinguishes them in a m atter of a second or less. One alternative would be to operate only a single backup lamp, and another, to activate only the license plate lamp. This would provide a warning to the following driver.

The agency is concerned with glare, but its investigation of the phenomenon indicates that there are two types: discomfort glare, and disabling glare. Although it is certainly an annoyance, the glare produced by a headlamp shining into a rear view mirror is discomfort glare. In our judgment, a vehicle driver looking into the mirror will not suffer disabling glare so that he is unable to discern vehicles approaching, or pedestrians in the roadway; most vehicles are equipped with manual "day/night" mirro rs which may be easily operated in the event of discomfort. Equipment manufacturers have already addressed the problem by providing rear-view mirrors that have a photoelectric cell that dips them when a certain level of light intensity is reached. In s ummary, the agency does not believe that there is a nationwide safety problem requiring it to mandate the use of your device on motor vehicles as new vehicle equipment.

As an aftermarket item which a dealer could offer a new-car purchaser, its installation would be subject to the general prohibition in Federal Motor Vehicle Safety Standard No. 108 that supplemental lighting devices shall not impair the effectiveness of the lighting equipment that Standard No. 108 requires. The question to be answered, therefore, is whether the device would impair the effectiveness of the backup lamps, or other rear lighting devices. The problem here is the necessity of rear lighting d evices to provide clear and unambiguous signals and

messages to following drivers. Anytime a lighting device does not provide a cue to which a following driver is accustomed, the potential for confusion arises. The driving public is unfamiliar with the sudden, though temporary, activation of the backup l amp, at normal driving speeds, or a modification in intensity of the license plate lamp. Without a substantial nationwide public education campaign, the signal imparted by your device is not likely to be understood by a following driver, and might distr act him from the signals of the other rear lighting devices. In this sense, we believe that your device might impair the effectiveness of the lighting equipment that Standard No. 108 does allow.

You have also noted the State prohibitions against use of backup lamps when the car is going in a forward direction. Even if the agency concluded that the device was permissible and would not cause impairment, the States are not precluded from enacting and enforcing their own standards on the use of lighting systems.

You may be interested to know that two letters to the Editor of The New York Times have appeared on this issue in the last month which suggest the use of existing lighting equipment to signal following drivers that their upper beams are on. I enclose th ese letters for your consideration.

I am sorry that we cannot be more encouraging in our remarks, but we do appreciate your interest in motor vehicle safety.

Enclosure

When the Driver Behind Is Blinding You

To the Editor:

Until we see the idea of a liquid crystal rear-view mirror, now in one Japanese luxury car, extended to side-view mirrors, as you propose in "Don't Stop There" (editorial, Jan. 18), there is a less than widely known way to dim the discomfort and dange r of bright headlights behind you.

While learning to drive in the Catskill Mountains around Monticello, N.Y., I discovered how to let the driver behind know that his or her brights are ripping out your retinas from the rear. As opposed to the signal for an oncoming driver (turning on your own brights, which is hard for an approaching motorist to miss, but useless for someone who can only see your tail lights), you deal with brights from behind by turning your lights completely off, then back on again.

Presumably, this demonstrates to the driver behind you, for a moment, that he or she is supplying enough light for both of you.

But there's a Catch-22. Drivers who know this signal are typically more experienced and rarely leave their brights on near other vehicles. The most frequent offenders are invariably ignorant of the signal.

As more drivers learn the meaning of the off-and-on signal, fewer of us, we may hope, will be blinded by the light from behind. TOM COBIN

Bayside, Queens, Jan. 18, 1990

Explaining Lights to the Driver Behind

To the Editor:

In "When the Driver Behind Is Blinding You" (letter, Feb. 3), Tom Cobin suggests turning your car headlights off and on several times to signal the driver behind that his or her bright lights are on.

But this can be dangerous. One's hands should be on the wheel when driving in traffic and not playing with the light switch. Also, driving for even a fraction of a second into an unlighted road is scary.

A safer method is to touch the brake pedal barely a time or two, to flash an alert, it is to be hoped, to the car behind that the lights are creating a problem.

The safest action is to slow down slightly and to let the offender pass, if the traffic permits. Then, a flash or two of your high beams in his or her rear view mirror might penetrate the skull of this particular thoughtless or careless driver, who i s but one representative of that large percentage at the wheel who should not be driving at all.

C. LINCOLN CHRISTENSEN Hurley, N.Y., Feb. 3, 1990

The writer is a longtime member of the Society of Automotive Engineers.