Decisions regarding low-beam headlamp modeling are generally made following evaluation of pedestrian target visibility and glare to oncoming motorists. Retroreflective traffic control signs are parts of the model that have long been ignored, yet they are essential adjuncts to safety. The widespread use of retroreflective materials forinformation, regulation, and warning signs and their inclusion in many official standards suggested that the comparison of u.S. And economic commission for europe (ece) lower-beam headlamps should be made to reveal the consequences of further light reduction above the horizontal axis. Comparison of photometrics above the horizontal axisin the direction of commonly placed traffic signs for a variety of distances was used to determine the luminances for three types of material. The study permits comparisons among existing headlamp types and illustrates the significant deterioration in sign luminances that accompanies the use of ece lower beam headlamps, or the alterationof u.S. Lower beam photometrics to more closely correspond to thoseof ece headlamps. The study permits some consideration of retroreflective material choice, depending on headlamp type, sign position, and sign luminance requirements. This paper appeared in transportation research record no. 1149, Visibility for highway guidance and hazard detection. For covering abstract see IRRD no 817811.
Abstract