Durable Fluorescent Materials for the Work Zone

Construction work zones (CWZs) are a major cause of concern for highway and safety engineers. At any given time CWZs constitute only a small fraction of the total roadway miles. However, they are the site of an increasing number of roadway accidents each year. The traffic safety industry has attempted to respond to this problem by providing brighter retroreflective signing materials to increase the nighttime visibility of the CWZ. The equally important need for increased daytime visibility has prompted traffic engineers to experiment with fluorescent colors in the CWZ. Fluorescent colors have outstanding visibility under all daylight driving conditions. Even so, fluorescent colors have never achieved widespread acceptance in outdoor signing applications. The primary obstacle has been the very poor color stability of fluorescent signing materials. A typical fluorescent roadway sign has lost most, if not all, of its color within 1 year. Often it is only a matter of months or weeks. Recent developments have resulted in a redefinition of the contribution that fluorescent colors can make toward improving traffic safety. A fluorescent retroreflective sheeting with color durability similar to existing CWZ sheetings is now available. A field study was run to compare the visibility performance of this fluorescent retroreflective sheeting with that of conventional fluorescent films and ordinary retroreflective materials. The results of the study indicate that fluorescent retroreflective sheeting provides better daytime and nighttime visibility than do ordinary signing materials.