Movement of Water through Ballast and Subballast for Dual-Line Railway Track
The purpose of effective track design is to ensure that load from trains can be safely supported by subgrade soils, which are likely to be affected by water. Because it is almost impossible to prevent water from entering the ballasted track and therefore affecting the underlying layers, it is vitally important that water can drain away rapidly. The study undertaken shows how water moves through a dual-railway track, which is either symmetrical about the centerline or superelevated with a continuous slope of the subgrade across both tracks. The study shows that water may be retained in the track nearest the drain for more than a week with possible consequential impact on increased deformation and therefore the need for more maintenance. It also shows that a high permeability composite may be included near the base of the subballast to effect significant improvement in track drainage.