Due to its improved safety and efficiency, the Mobile Retroreflectometer Unit (MRU) has been recognized by many highway agencies as an appealing alternative to the handheld retroreflectometers. The Florida Department of Transportation (FDOT) has been researching the use of the MRU for evaluating pavement markings continuously and reliably at traffic speeds. Since thestripe surface is non-uniform and the measurement process relies on the operator-driven instrument device, a level of uncertainty is always a concern in evaluating pavement markings with the MRU. As part of the broader effort for MRU implementation, this research is aimed at assessing the precision of the MRU in terms of repeatability for pavement marking retroreflectivity. A total of six designated sections of roadway were selected at random to include testing on various pavement surfaces and pavement stripes.The data was analyzed to determine the pavement marking characteristics at each test location, in terms of retroreflectivity at 80 km/h (50 mph) using the reduced 30 meter geometry standard. The results indicated that theretroreflectance values from two properly conducted tests using the same MRU on the same pavement marking should not differ by more than 20.1 mcd/m2/lux or 6.7 percent at a 95 percent confidence level for the retroreflectivity values ranging between 200 and 450 mcd/m2/lux. This paper presents adescription of the testing program, the data collection effort and the subsequent analyses and findings.
Abstract