Brands and types of retroreflective material for use on Swedish road signs have professionally been applied to the same road sign. These signs were then exposed to traffic along three rural roads for 4,5 years (5 winters). The retroflection of the materials on each sign was measured before exposure (as new) and then after careful cleaning after the second, third, fourth and fifth winter in traffic. The main result is that the retroflective sheeting, independent of brand as well as type, lost about the same relative amount of retroflective power. The loss was about 10% each year and about 50% of the initial value remained after the fifth winter. (A)
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