Performance and environmental assessment of prefabricated retroreflective spots for road marking

Road markings are necessary basic features that increase road safety; they are currently irreplaceable for both human drivers and the emerging automated vehicles technology. Retroreflectivity, achieved through incorporation of glass beads, is their key property, particularly important during driving at night time and in inclement weather conditions. One of modern road marking materials is cold plastic, which can be applied at either thick-layer structure or a thin-layer flat line and always must be reflectorised. An option for reflectorisation, particularly popular in Asia, is the use of prefabricated retroreflective spots. In a field test their performance was compared against two types of glass beads. The outcome indicates that the use of retroreflective spots brings no advantage either from the perspective of performance or environmental protection. The measured service life of road markings reflectorised with premium glass beads was almost three times longer as compared to obtained with the prefabricated retroreflective spots; initial performance was almost equal. Environmental assessment, based on series of renewals to maintain the required minimum retroreflectivity for 10 years, also confirmed significant disadvantage associated with the utilisation of the retroreflective spots. The use of premium glass beads would require only 29 % of titanium dioxide and 40 % of the resins that would be demanded with the use of retroreflective spots. Hence, from the perspective of long-term performance and minimisation of carbon footprint, utilisation of premium glass beads to reflectorise sprayed cold plastic was advantageous because they provided very good initial performance that was long-lasting.