The Florida Department of Transportation (FDOT) has historically used a combination of handhelddevices and visual surveys to evaluate the retroreflectivity of pavement markings. However, visualsurveys have the inherent limitations of operator bias while the use of a handheld device is slow, laborintensive, and presents safety hazards. Many highway agencies have recognized that a MobileRetroreflectivity Unit (MRU) may be a safer and a more efficient alternative to the handheldretroreflectometers. Since the measurement process relies on the operator-driven instrument, a level ofuncertainty is always a concern in evaluating pavement markings with the MRU. This research is aimedat assessing the precision and bias of the MRU while using the handheld retroreflectometer as a referencedevice. A total of ten 1.0 mile long field sites were selected to include various pavement surface typesand pavement marking materials (paints and thermoplastics). The results indicated that, when comparedto the handheld retroreflectometers, the MRU demonstrated no statistical differences or bias at a 95percent confidence level for the retroreflectivity values ranging between 200 and 800 mcd/m~2/lux. Inaddition, it was determined that the retroreflectivity values from two properly conducted tests using asingle MRU on the same pavement marking should not differ by more than 7.8 percent and whendifferent MRUs are used on the same pavement marking, the retroreflectivity values should not differmore than 13.3 percent. This paper presents a description of the testing program, the data collection effort,and the subsequent analyses and findings.
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