MEASURING RETROREFLECTIVITY OF PAVEMENT MARKINGS

THE MEASUREMENT OF THE RETROREFLECTIVITY OF PAVEMENT MARKINGS OR TRAFFIC STRIPING HAS BEEN LIMITED BY THE INSTRUMENTATION AT PRESENT. THE MAJORITY OF THESE INSTRU- MENTS ARE HAND-HELD PORTABLE UNITS WITH LIMITED GEOMETRY ANDNEASUREMENT AREA. MOBLE UNITS BUILT BY SOME STATES ALSO ARE LIMITED IN THEIR PERFORMANCE BY STRAY LIGHT, NON-OPTIMUM GEOMETRY AND OTHER PROBLEMS. A NEW RETROREFLECTOMETER IS PROPOSED WHICH WILL ALLOW VARIABLE MEASUREMENT GEOMETRY, SAMPLING AREA, SIMPLE, RELIABLE AND CALIBRATED MEASUREMENT OF THE RETROREFLECTANCE OF PAVEMETN MARKINGS. IT WILL BE MOBLE, ALLOWING USE WITH PRESENT PAVEMENT STRIPING EQUIPMENTTO MONITOR THE QUALITY OF THE APPLIED COATING AS WELL AS DETERMINING THE DEGRADATION OF TRAFFIC MARKING IN PLACE. THEINSTRUMENTATION PROPOSED USES A COST-EFFECTIVE, OPERATION- ALLY SIMPLE, LASER RETROREFLECTOMETER TO MEASURE THE RETROREFLECTIVITY OF PAVEMENT MARKINGS UNDER DAYLIGHT ILLUMINATION. A CONCEPTUAL LABORATORY LASE DEVICE HAS BEEN DEMONSTRATED FOR LINE COMPARISONS UNDER BOTH WET AND DRY CONDITIONS. THIS PROPOSAL WILL DEVELOP AND TEST A WORKING BREADBOARD MODEL WHICH WILL ALLOW PAING CREWS TO EFFECTIVELYMONITOR THE RETROREFLECTIVE QUALITY OF THE LINE AND ADJUST THEIR STTRIPING EQUIPMENT ACCORDINGLY.