The measurement of the retroreflectivity of pavement markings or traffic striping has been limited by the instrumentation at present. The majority of these instruments are hand-held portable units with limited geometry and measurement area. Mobile 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 pavement markings. It will be mobile, allowing use with present pavement striping equipment to monitor the quality of the applied coating as well as determining the degradation of traffic marking in place. The instrumentation 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 paving crews to effectively monitor the retroreflective quality of the line and adjust their striping equipment accordingly. Res: the breadboard retroreflectometer and results of the testing will lead directly into manufacture of prototype instruments and commercial units to be used in active monitoring of the retroreflectivity of pavement markings.
