# Temporary Road Marking Paint for Vehicle Perception Tests
## 4 Results
### Reflectivity  
Reflectivity was only measured during the second trial phase for samples 3 and 4. Figures 5 and 6 show the reflectivity of the two samples from the second trial with and without retroreflective beads as well as the reflectivity of the asphalt surface. The y-axis  
Figure 7: Weather during experiment phase in 2023.  
shows the reflectivity value, and the x-axis shows the measurement instance. Included in the figures is the measurement of reflectivity immediately after the removal of the paint. Hence, the data presented in this part of the figures do not show the measurements of the paint--they show the measurements of the asphalt at the location where the paint was before removal to detect potential phantom tracks.  
Figure 5 shows the diffuse reflectivity (daytime visibility). The diffuse reflectivity of the asphalt is similar for all measurements (55-64 mcd/(lx \(\times\) m\({}^{2}\))). Small fluctuations might be caused by different degrees of wetness. Both samples (with and without retroreflective beads) still provide sufficient visibility after two weeks; however, after four weeks, only sample 3 is above the threshold value of 130 mcd/(lx \(\times\) m\({}^{2}\)). It can be noticed that the daytime visibility degradation is significantly higher within the first two weeks. A potential explanation for this initial decrease is provided by the measured precipitation intensities over the course of the experiment. Rainfalls with high precipitation intensities occurred within the first week of the experiment between 30 March and 1 April 2023, and possibly washed away the retroreflective beads. The diffuse reflectivity values after the removal range from 73 mcd/(lx \(\times\) m\({}^{2}\)) for sample 4 with beads up to 83 mcd/(lx \(\times\) m\({}^{2}\)) for sample 3 without beads, which is above the asphalt's diffuse reflectivity of 60 mcd/(lx \(\times\) m\({}^{2}\)). This indicates phantom tracks. However, the diffuse reflectivity was lowered significantly by the removal process. A reason for the higher diffuse reflectivity after the paint was removed could be that the high-pressure water cleaner removed smaller particles between the construction aggregate particles, exposing reflective rock. This effect could fade over time as the crevices are filled with dust and abrasion by weather and vehicle overruns.  
Figure 6 represents the retroreflectivity (i.e., the nighttime visibility) of the road markings. The retroreflectivity of the asphalt remains similar for all measurements in a range of 19-21 mcd/(lx \(\times\) m\({}^{2}\)). Both samples 3 and 4 show degradations in visibility over time, especially within the first two weeks, when glass beads were used. As expected, the retroreflectivity initially is significantly higher when beads are used, which confirms the effectiveness of the beads. For sample 4, the retroreflectivity of the line with beads drops to the same level of the line without beads, which suggests that beads were removed during the first two weeks, possibly due to rain. The retroreflectivity of sample 3 is noticeably higher than the retroreflectivity of sample 4. Only sample 3 with beads can be assumed to be above the recommended visibility threshold of 100 mcd/(lx \(\times\) m\({}^{2}\)) during the first two weeks, since it was just marginally below the threshold (96 mcd/(lx \(\times\) m\({}^{2}\))) at the time of measurement. The sample was therefore categorized as a class R2 road marking (R\({}_{\rm L}\)\(\geq\) 100 mcd/(lx \(\times\) m\({}^{2}\))) according to EN 1436 [30]. After the removal, the phantom track measurements revealed values between 30 mcd/(lx \(\times\) m\({}^{2}\)) for sample 4 without beads and 38 mcd/(lx \(\times\) m\({}^{2}\)) for sample 3 without beads, which is above the values of adjacent asphalt at 21 mcd/(lx \(\times\) m\({}^{2}\)).