Low Cut-off Headlights
Since the late 1990s, vehicle manufacturers have transitioned to new headlight designs like Visually Optically Aimable (VOA) or low cut-off headlights. Designed as a solution to reduce the amount of glare drivers experience from oncoming traffic, these headlights have a sharp, horizontal cut-off and emit little light above the headlight level. Low-cut off headlights have a profound effect on a vehicle’s ability to illuminate road signs.
The most recent headlight models in the U.S. do not provide as much illumination as did an average vehicle in 1997 for the most commonly viewed signs (on the right shoulder) at distances associated with typical sign reading. For a typical right-shoulder mounted sign in the U.S., viewed at distances between 300 feet and 900 feet, the reduction in illumination from 1997 to 2011 model headlights was anywhere from 24 percent up to 48 percent. ¹
With newer generation VOA headlights sold in 2004 through 2011 model vehicles, some disadvantaged locations (left shoulder and overhead signs) showed slight improvementd in illumation.¹ However, considering that a left shoulder mounted sign receives around 20 percent, and an overhead sign receives around 10 percent, of the illumination received by the right shoulder mounted sign, these signs are still very disadvantaged in terms of headlight illumination.
¹Flannagan, M.J., and Schoettle, B., An Analysis of Low-Beam and High-Beam Headlighting Performance in the U.S.: 1997-2011, University of Michigan Transportation Research Institute, 2012
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