Minimizing infiltration of water in pavement structures has long been a priority of pavement designers. Incorporation of subsurface edgedrains is frequently an integral part of an pavement drainage system. In order for such a system to be effective however, it must be properly installed and maintained. With advances in video technology, inspection of edgedrain systems can now be conducted quite efficiently. This report documents the results of 287 video inspections of highway edgedrain systems in 29 states. These inspections were conducted to both demonstrate the capabilities of the technology as well as demonstrating some of the common problems associated with the performance of edgedrain systems. Findings indicated not only that the equipment was quite effective in identifying edgedrain performance concerns, but also how widespread the concerns of edgedrain performance are. Almost one third of the systems inspected had nonfunctional outlets, another third were either found to have non-functional mainlines or the mainlines could not be inspected due to physical obstructions. Only one third of the systems inspected were found to be performing as intended. Recommendations are provided for edgedrain design improvements to facilitate performance of the system and their inspections as well as recommendations to improve quality control during construction. Suggestions are also provided for maintenance procedures to address concerns identified in the inspection process. A Draft Guide Specification For Video Edgedrain Inspection and Acceptance is also provided as an Appendix.

At head of title: National Cooperative Highway Research Program.

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.