Edge drain systems are used on new highway construction projects and rehabilitation projects to reduce the moisture content of the pavement block and subgrade. Maintaining dry conditions in and around these components increases the subgrade strength and extends a pavement’s surface life. Edge drain systems can only operate effectively, however, if the entire subsurface drainage system functions properly. While many studies have demonstrated the benefits of edge drain systems, no comprehensive investigation of their performance has been undertaken in the state of Kentucky in over 20 years. After the Kentucky Transportation Cabinet (KYTC) identified problems with an edge drainage system along a segment of Interstate 275 in Kenton County, the agency commissioned researchers at the Kentucky Transportation Center (KTC) to evaluate the performance of edge drains on roadway segments that will be resurfaced in the coming years. Researchers comprehensively inspected 10 roadway segments, assessing several components of their edge drain systems. For edge drain systems with headwalls, researchers found that all headwalls (n =126) were in good condition and free of structural issues. Roughly 29% of the outfall waterways prevented the flow of water from the headwall, while 65% of the outlet waterways were blocked to some extent by gravel, mud, silt, or other debris, and 61% of the outlet pipes were obstructed. Of the edge drain systems draining to catch basin inserts or ditch bottom inlets (n = 110), outfall waterways were clear on 97% of the systems, but just 14% of the edge drains were unobstructed. Based on inspections, edge drain systems were classified as good, compromised, or undetermined (the final designation being used if conditions prevented a full inspection) and identified a probable failure mode. Approximate 75% of the problems found during inspections were related to maintenance, with the remainder the product of construction activities. To preserve edge drains in a functional condition, post-installation inspections should be conducted, and yearly inspections and cleanings of headwalls and outlet pipes completed. Other methods for outletting water (e.g., dry wells) can also be explored.

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© 2018 University of Kentucky, Kentucky Transportation Center

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The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky, the Kentucky Transportation Center, the Kentucky Transportation Cabinet, the United States Department of Transportation, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. The inclusion of manufacturer names or trade names is for identification purposes and should not be considered an endorsement.