Systematic Testing of Road Markings’ Retroreflectivity to Increase Their Sustainability through Improvement of Properties: Croatia Case Study

Abstract

Road markings are important elements of road infrastructure, influencing traffic safety. Since they are deteriorating systems, their upkeep through renewals is important. To assure the quality of the renewal jobs, the systematic testing of retroreflectivity, which is the key performance parameter of road markings, was imposed in Croatia. Results from two decades of annual measurements of renewal jobs are provided. For the first decade, the measurements were taken statically, at spot locations, and later dynamically, across the entire road segments. When the evaluation started, only 1 out of 18 tested job sites was exceeding the minimum requirements; only after 8 years of measurements, 100% of the jobs exceeded the minimum demands. A subsequent switch to dynamic testing revealed that, on average, only 71% of the renewed road markings were in satisfactory condition and approximately 1.22% of the analysed line lengths had grossly substandard retroreflectivity. These results demonstrated that the field verification of jobs quality is necessary and simultaneously showed that static localised testing was not adequate. The outcome underlines the need for the strict supervision of road maintenance contracts to maximise the benefits for the society: through the better visibility of road markings, road safety should also improve, and the entire system will become more sustainable.