Raised Pavement Marker Assessments Using Mobile Retroreflectivity Unit Technology

Abstract

Currently, the Florida Department of Transportation (FDOT) State Materials Office collects 25,000 lane miles of line-stripe pavement marking (PM) retroreflectivity data each year using RoadVista Laserlux G7 (LLG7) mobile retroreflectivity units (MRUs). The focus of this study was to configure an LLG7 MRU to accurately and repeatably detect and measure the retroreflectivity of in-service Class B raised pavement markers (RPMs) while simultaneously collecting PM retroreflectivity data. At this time, FDOT assesses the quality of in-service RPMs as part of a visual inspection. Currently, there are no standards or devices for mobile RPM retroreflectivity measurements. As these LLG7 MRUs were designed to measure PMs in units of RL (mcd/m2/lux), an additional objective was to derive regression equations that correlate the industry-standard units for RPMs (RI [mcd/lux]) and the RL values collected by the MRU. Through research-based experiments and with coordination from RoadVista, modifications were made to the LLG7 MRU to detect and measure RPM retroreflectivity in relation to RL. Regression equations were derived pertaining to retroreflectivity measurements between a handheld RPM retroreflectometer (RI) and an LLG7 MRU (RL) on in-service RPMs. The results indicate that the modified MRU can be used to effectively assess RPM retroreflectivity in tenth-mile intervals in a highly repeatable manner with an average error in estimated RI of ±13.5% without affecting PM data. Overall, utilizing the modified MRU for statewide RPM assessments is a significant improvement from the current process of visual assessments and allows the FDOT to quantify RPM quality on a network level.