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Principles of Drainage (Room Sagamore 1)

Railroad tracks are comprised of a system of substructures – subballast, ballast, ties, rail - that work together to distribute train axle loads into the earth. In a controlled environment where the only forces on a track are imposed by trains, track degradation would be predictable and consistent. However, in the real world, many factors impact the track substructures singularly or in combination, leading to unpredictable and sometimes immediate weakening of the overall track system. No external condition has as much impact on the track structure as surface water. Standing water, stormwater runoff and area flooding are among the various sources of water intrusion on the track structure that can degrade track quality. Therefore, moving water away from the track, and preventing water from reaching the track, are among the most important strategies to increase track reliability and decrease maintenance costs. This paper discusses strategies for effective drainage of surface water and prevention of track saturation. Effective drainage begins with understanding how and where water is reaching the track structure. Once water reaches the track, the track owner must know what happens to the water – does it pool in depressions against the track roadbed? Does it saturate fouled ballast? Does it seep into the subballast and soften the roadbed? With this understanding, the track owner can employ civil engineering solutions to move water away from track, and track maintenance solutions to remediate track already impacted by water.