The Texas Department of Transportation (TxDOT) maintains more than 186,000 lane-miles of roadway. Each year it also contracts or completes seal coating as a preventive maintenance treatment on about 20,000 lane-miles (1, 2, 3). The seal coats in Texas use relatively large aggregates and are often applied under hot, dry, and windy conditions. The pavement markings placed on these new seal coats typically include sprayed thermoplastic and water-based paint. Unfortunately, these pavement markings have not performed as expected in terms of durability and retroreflectivity. The four-year project described in this paper was designed to investigate the reasons for these seal coat pavement marking performance problems. It includes the investigation of pavement marking materials and application methods at closed-course test areas and pavement marking test deck sites along Texas roadways. The ten pavement markings evaluated at the closed-course facility were installed on four individual seal coat surfaces and will be subjected to various accelerated wear methods. An attempt will also be made to compare and/or correlate the results from these activities to similar measurements taken from the Texas roadway test decks. The feasibility of using a device to remotely monitor the application speed of ongoing pavement marking installations will also be investigated. This paper describes the overall problem addressed by this project, its objectives, and the ongoing and planned project activities proposed for its completion. Preliminary and expected results or outcomes from these activities are presented.
Abstract