Abstract:
GLASS BEADS INCREASE THE NIGHT VISIBILITY OF PAINTED TRAFFIC STRIPES TO A GREATER DEGREE THAN OTHER AVAILABLE MATERIALS. SMALLER BEADS OFFER ADVANTAGES IN ECONOMY AND SERVICE LIFE OVER THE LARGER SIZES FORMERLY USED. WITH SMALL BEADS THE RANGE IN TYPES OF SUITABLE PAINTS IS GREATLY EXTENDED SINCE THE SPECIAL QUALITY OF HIGH CAPILLARY RISE AROUND THE BEADS IS OF LESS IMPORTANCE. METHODS OF TEST FOR PAINTS FOR USE WITH BEADS ARE THE SAME, WITH A FEW EXCEPTIONS, AS THOSE USED FOR PLAIN TRAFFIC PAINTS. BEADS WERE ORIGINALLY APPLIED BY GRAVITY TO THE FRESH SURFACE OF THE STRIPE. THIS METHOD, CALLED "OVER-LAY", HAS BEEN SUCCEEDED IN WASHINGTON BY A "PREMIX" METHOD IN WHICH THE BEADS ARE MIXED WITH THE PAINT JUST PRIOR TO APPLICATION BEADS ARE RETAINED IN THE STRIPE, INITIALLY AND DURING SERVICE, MORE UNIFORMLY WHEN THE PRE-MIX METHOD IS USED. WHEN STRIPING MACHINES ARE NOT WELL ADAPTED TO THE USE OF PRE-MIX BEADS THE "FOG-COAT" METHOD IS USED AS AN ALTERNATE. IN THIS METHOD, BEADS PLACED BY OVER-LAY ARE GIVEN A SECOND LIGHT APPLICATION OF PAINT TO AID IN THEIR RETENTION DURING SERVICE. DATA ARE GIVEN ON THE USE OF THE PRE-MIX AND FOG-COAT METHODS. LONGER SERVICE LIFE OF THESE STRIPES MAKES THEM AVAILABLE ECONOMICALLY FOR MANY ROADS NOT PREVIOUSLY TREATED WITH REFLECTORIZED STRIPES. FIELD BRIGHTNESS MEASUREMENTS OF TRAFFIC STRIPES 6 TO 8 MONTHS OLD, SUPPLEMENTED BY LATER VISUAL SURVEYS, SHOW THAT THESE APPLIED BY THE PRE-MIX METHOD RETAIN A UNIFORM AND ADEQUATE DEGREE OF BRIGHTNESS THROUGHOUT THEIR LIFE. THE USEFUL LIFE OF PRE-MIX STRIPES IS CONSIDERABLY LONGER THAN THAT OF A SIMILAR STRIPE WITHOUT BEADS. THE FOG-COAT STRIPE IS INFERIOR TO THE PRE-MIX STRIPE IN UNIFORMITY BUT RESULTS IN BETTER BEAD RETENTION THAN THE OVER-LAY STRIPE. /AUTHOR/
Supplemental Notes:
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