Interpretation ID: nht88-3.7

TYPE: INTERPRETATION-NHTSA

DATE: 08/16/88

FROM: RICHARD H. SCHULTZ -- AMERICAN PULSE LIGHTS INC

TO: ROBERT KNAUFF DESIGN

TITLE: NONE

ATTACHMT: ATTACHED TO LETTER DATED 07/24/89 FROM STEPHEN P. WOOD -- NHTSA ROBERT KNAUFF; REDBOOK A33; FMVSS 108; LETTER DATED 06/08/89 FROM ROBERT J. KNAUFF -- APPLIED RESEARCH AND DESIGN INC TO KATHLEEN DEMETER -- DOT; LETTER DATED 12/07/87 FROM RICHARD H. SCHULTZ -- AMERICAN PULSE LIGHTS TO ROBERT J. KNAUFF

TEXT: Dear Mr. Knauff:

This is an evaluation of your school bus rear warning lamp demonstration with a pop-flash option.

I initially expected that we would have a problem with high intensity flash washing out the red lens and appearing white. Technically this is what happens and if you concentrate on it, the flash can appear white. The flash duration however was so brief and when used in concert with red in the cycle did not appear white to me. That should clear one obstacle, as white is prohibited in this type of lamp. Dual day/night intensity should not be necessary as long as you stick with red lamps.

You should also not have to restrict the pop to less than every flash, but in any case you will have to locate the discharge bulb so that the parabolic reflector and lens of the host lamp project the energy at very nearly about the H-Y point. Any large amount that occurs down at a level so as to be observed by a passenger car operator less than, let us approximate, 200 feet away would probably be objectionable to some, depending upon a number of factors that I need not go into at this point.

Generally, we have a basic concept that a signal is either required or not permitted. This keeps messages clear between vehicle operators. In this case however, I believe that we can consider this option since it is only an appendage modification of an existing warning system.

When you clear this modification with the National Highway Traffic Safety Administration compliance office and with the Minnesota Department of Education student transportation office, we would need to have a look at the finished product and your test da ta for purposes of commissioner's authorization or commissioner's approval certification depending upon the marketing approach that is possible and that you wish to take.

Sincerely,