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The Kentucky Department of Highways (DOH) has been trying to remove water from its pavements since the early 1970s. Aggregate-filled trenches were used to remove water in the early 70s and perforated pipe edge drains were introduced in the mid-1970s. These systems remained relatively unchanged until the late 1980s. In 1987, after a number of localized pavement failures throughout Kentucky, the Kentucky Transportation Center (KTC) and the Kentucky DOH started evaluating the effectiveness and performance of these edge drain systems. It was found that most of the panel edge drains were significantly damaged during installation and that approximately 50% of the outlet pipes were crushed and/or the headwalls were clogged. As a result of these findings, several design changes were made in 1989. Research conducted between 1989 and 1991 indicated that the performance of the system had improved but failures still existed. In 1997, after the completion of an in-depth research study on the performance and construction of these systems the Kentucky DOH required that all edge drain outlets be inspected with a pipeline inspection camera. The contractor was made responsible for inspecting and repairing his own work. This was the early stages of a quality control (QC) program for edge drains in Kentucky. The camera inspections decreased the number of edge drain outlet failures from approximately 20% to approximately 3% to 5%. Of the 3% to 5% found damaged, the contractor was responsible for complete repairs. Current failure rates for mainlines are approximately 2%. At this time only 1/3 of the mainline is being inspected (headwall to approximately 150 ft into the mainline). In May 1998, the Kentucky DOH established a mission to incorporate quality into their construction projects by transitioning, where possible, from method specifications to QC/QA, performance related, warranty, and other innovative specifications for the year 2000. In 1998, a team was formed to evaluate the current edge drain specification and make recommendations and revisions towards a full fledged QC/QA specification. This paper discusses the historical performance of edge drains in Kentucky and the recent changes in the specification.
pavement drainage, edge drains, performance, construction, QC/QA, specification
Senior Research Investigator, University of Kentucky, Kentucky Transportation Center, Lexington, KY
Chief Research Engineer, University of Kentucky, Kentucky Transportation Center, Lexington, KY