|Abstract:||This study was conducted to verify the compliance of vehicular and pedestrian LED traffic signal modules with the Institute
of Transportation Engineers specifications; and to assess drivers’ preferences of the LED modules. Four vehicular modules
(ACS, Dialight, Leotek, and Lumination) and three pedestrian LED modules (Dialight, Leotek, and Lumination) were used.
The compliance verification primarily involved reviewing the independent-lab testing reports, visual inspection of the
modules, and analyzing the manufacturers’ responses to the questionnaires prepared by the research team. The solid LED
modules provided by ASC had several issues with compliance with the ITE specification; however, the modules from other
companies either complied or complied with reservation with all the ITE Specifications. No general conclusion were made
for the arrow modules since at the time of completion of this study, ITE had not adopted a final specification for them. For
pedestrian modules, all companies submitted independent lab test reports for some of the modules, but not for all. The
reports showed that all these modules either complied with, or complied with reservation with most of the ITE specifications.
To assess drivers’ preferences, 120 drivers participated in the evaluation of the modules. For solid modules in daytime, the
participants’ ratings for the ASC were significantly higher than the other three companies. In nighttime, the ASC red module
was rated much brighter than the Leotek module. However, for solid yellow and green modules, the brightness was rated
the same for all companies. For red arrow modules in daytime when looking straight ahead, Dialight was rated similar to
ASC, but significantly higher than Lumination and Leotek. However, for yellow and green arrows, Dialight was rated higher
than all other three companies were. For all three colors of the arrow modules in daytime when looking at an angle, Dialight
and ASC were rated significantly higher than Leotek and Lumination. For the pedestrian modules in daytime, the separate
12” Dialight module was rated significantly higher than the Leotek and Lumination modules. For 12” combination modules,
Leotek and Dialight were rated higher than Lumination. For the 16”*18” combination modules, Lumination was rated
significantly higher than Dialight. In rating the traffic modules, all of the respondents chose brightness, 93% chose color,
and 88% selected uniformity as an important factor. The most important factor was brightness for 74%, color for 26%, and
uniformity for 27% of the participants. In rating of the pedestrian modules, all of the respondents chose brightness, 94%
chose color, 90% selected uniformity, and 70% selected size as an important factor. The most important factor was
brightness for 75%, color for 25%, uniformity for 25%, and size for 23% of the participants.