The intent of this project was to develop retroreflectivity degradation curves for roadway pavement markings. To accomplish this objective, this study utilized a vehicle-mounted Laserlux retroreflectometer to take measurements on approximately 80 test sections throughout Washington state.
The resulting retroreflectivity values from roadways with similar average annual daily traffic (AADT) and environments displayed a significant amount of variability. Best-fit trendlines were extrapolated to determine when each category of paint would fall below a selected minimum threshold of 100 mcd/m2/lux and require repainting.
Unfortunately, given the variability of the data observed to date, it may not be possible, even with the collection of more data, to create striping performance predictions that have a high level of statistical confidence. The data do not suggest conclusively that the existing WSDOT striping schedule should change. According to that schedule, long line painted markings should be painted at least once a year, and heavy wear, long line pavement markings should be painted at least twice a year.