Mr. Shigeyoshi Aihara
Project Manager
Regulation and Compliance
Ichikoh Industries, Ltd.
80 Itado Isehara-City
Kanagawa Pref. 250-1192

Dear Mr. Aihara:

This is in reply to your letter of October 21, 1999, asking for an interpretation of Standard No. 108's requirements for visibility of front turn signals. You have made this request for a specific design which you have enclosed. I am sorry that our reply has been delayed.

This design depicts a lamp assembly containing a headlamp and a turn signal lamp. The assembly has a transparent lens. The turn signal lamp has a separate amber lens inside the assembly. Standard No. 108 requires that "to be considered visible, the lamp must provide an unobstructed view of the outer lens surface, excluding reflex reflectors, of at least 12.5 square cm measured at 45 deg. to the longitudinal axis of the vehicle." (paragraph 5.4.1 of SAE Standard J588 NOV84 incorporated by reference in Standard No. 108). Your question, in essence, is whether the "outer lens surface" is the surface of the amber lens of the turn signal lamp alone, or that portion of the surface of the transparent lens of the entire lamp assembly that is in front of the amber lens of the turn signal lamp. The drawing you furnished identifies the "unobstructed view area" measured at the 45 deg. observation angle with respect to the amber lens alone as

" C." The "unobstructed view area" measured at the 45 deg. observation angle with respect to the amber lens projected on the transparent lens in front of it is identified as "B." The area of "B" is much larger than the area of "C." You have asked for confirmation that the transparent lens surface may be regarded as the "outer lens surface" and that unobstructed view area "B" is acceptable under Standard No. 108.

I regret that we cannot confirm your interpretation. It is clear to us that the term "outer lens surface" as used in SAE's and NHTSA's turn signal lamp standard, SAE Standard J588 NOV84, for the purpose of observable lens area of a signal lamp, means the lens of the turn signal lamp itself. When the turn signal lamp is part of a larger assembly with a separate lens, the term"outer lens surface" continues to mean the lens surface of the turn signal lamp, the lamp that is actually providing the light, without reference to the surface of the lens of the larger lamp assembly. Thus, area "C" is the area that must meet the visibility requirements.

Frank Seales, Jr.
Chief Counsel