Interpretation ID: nht90-2.79

TYPE: Interpretation-NHTSA

DATE: June 11, 1990

FROM: Samson Helfgott -- Helfgott & Karas, P.C.

TO: Stephen P. Wood -- Acting Chief Counsel, NHTSA

TITLE: Re Our File No.: CAIN 8877 Automotive Warning and Brake Light Arrangement

ATTACHMT: Attached to letter dated 9-17-90 from P.J. Rice to S. Helfgott (A36; Std. 108)

TEXT:

My client, Harold A. Caine, and the Safety Autodrivers Foundation for Education (S.A.F.E.) of Freeport, New York, had previously submitted an inquiry and received a response from your office on March 30, 1989. Their previous inquiry related to the use o f an amber lamp adjacent to the center high-mounted stop lamp, in a separate housing and wholly independent thereof, which would be activated when the ignition is turned on and deactivated when the stop lamps are illuminated.

My client is presently interested in the possibility of providing an "amber triangular array" on the rear of the car comprising the amber center high-mounted lamp of the previous inquiry in conjunction with the existing amber directional signals. This " amber triangle" would be present both day and night, and would turn on when the ignition is turned on and would be deactivated when the stop lamps are illuminated. A driver looking ahead to a leading vehicle would, therefore, always see an "amber triang ular array" until the brake lights are put on whereupon he then sees a "red triangular array". Enclosed is a single sheet effectively describing this concept.

We believe that this "amber triangular array" would have numerous benefits. Firstly, the amber color is already associated with a "warning" situation and, accordingly, trailing drivers seeing the "amber triangle" would be in a state of warning and would react more positively to the sudden turning on of the red triangle during a braking condition.

Secondly, the present existence of the constant red lights on the back of the vehicle which intensifies upon application of brakes, is more confusing than a situation where a color change occurs between non-braking and braking.

Thirdly, we believe that the amber light is a more suited color for continuous illumination. Specifically, a far-sighted driver would see a green light clearest while a near-sighted driver would see a red light clearest. The amber light is less effecte d by the driver's retroactive error than either red or green.

Fourthly, amber is preferable because of the chromeostereopsis effect. (The perception of colors at different distances due to chromatic aberration and slight optical element misalignments in the eye and/or due to prism incorporated in spectacle lenses). For about half the population, green will be seen closer than amber, while for the remainder of the population, green will be seen farther away. Since the average

illumination at night is yellowish, an amber light will not be subject to chromeostereopsis errors in distant judgement by any part of the driving population, whereas green, or other colors, could be subject to significant error in judgement of distance.

I believe that in order for us to determine the possibility of utilizing the "amber triangle" a number of areas must be addressed, and I would appreciate your addressing each of these:

1. The possibility of utilizing the amber turn signals as tail lights, instead of the red tail lamps. This is the same as is now in effect on the front of all vehicles.

2. The possibility of supplementing existing tail lamps with the presence of the amber lamps.

3. The possibility of using the amber lamps as daytime running lamps on the rear of a vehicle.

4. The possibility of utilizing the "amber triangular array" as described above.

In addition to any advisory opinion that you may be able to provide for us, if there is any technical information that your technical staff may have available in connection with this inquiry, we would appreciate your sending it to us. At the same time, should your technical staff not have yet considered the possibility of the "amber triangle" as described above, or the use of daytime running lights on the rear of a vehicle, perhaps you can forward this letter to them for their consideration of these as pects.

I do look forward to hearing from you on this matter.