Tinted lenses and the ANSI standards for traffic signal transmittances.

The transmittance properties of 96 tinted lenses were examined to determine whether these lenses met the American National Standards Institute (ANSI) Z80.3 standards for traffic signal transmittances and color shifts. Transmission functions of the lenses were measured using a Zeiss Spectrophotometer, and the luminous transmittances and color shifts were calculated according to the ANSI guidelines. Approximately 50% of the sampled tinted lenses failed to meet at least 1 of the ANSI requirements. Lenses that failed to meet several ANSI requirements were often special purpose sun lenses. Although the special purpose tinted lenses do not have transmittance requirements for traffic signals, it is not always clear from the manufacturers' brochures that the lenses may be unsuitable for driving.