Retroreflective color plates are important carriers for transmitting retroreflective chromaticity, and they can be used to calibrate portable retroreflection colorimeters. Measurement errors in the chromaticity measurements of retroreflective color plates create uncertainty of the retroreflective chromaticity coordinates. To study the uncertainty in the measurements of retroreflective chromaticity plates, we analyzed the uncertainty sources and evaluated the uncertainty of the chromaticity coordinates of a retroreflective color plate measured using a remote spectrum measurement system. The results showed that for a confidence probability p = 95% and coverage factor k = 2, the expanded uncertainties of the chromaticity coordinates of the retroreflective color plate, U(x) and U(y), were both 0.01. The evaluation results showed that the uncertainty of the spectrometer contributed to the uncertainty the most, mainly because the large uncertainty components arose from the measurements of the retroreflective color plate and the standard white plate.
Depending on the retroreflective distribution measuring device, three sets of controlled experiments were designed. To obtain the retroreflective distribution of road traffic markings, the coefficient of retroreflected luminance (RL) changes of road traffic markings under different measurement geometry was analyzed. Several observation angles commonly used in retroreflection measurements were selected. The deviation range of vertical entrance angles was set to 8°. The horizontal entrance angles were selected according to the horizontal measurement angle of a mobile retroreflectometer unit. A white road traffic marking sample, which measured 10 mm × 46 mm, was used in the experiments. The results showed that the retroreflective distribution of road traffic markings was not uniform, the influence of the change of observation angle on the RL was greater than the entrance angle, and the change of retroreflection in the direction of the vertical entrance angle was more obvious than the horizontal entrance angle.
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