Figure 2.10. Grouting Corrects Water Pocket.
replacing it with stones or rocks. Water cannot be trapped in the rocks because of the many
passages between them; this action cures the water pocket. If trains are operated over the
railroad while the French drain is being constructed, some form of temporary support is needed
to hold up the tracks with the fill material removed. This support may be timber shoring, heavy
wooden beams, and columns that serve as a bridge. These members are removed when the stone
is in place.
Drainage is important in track maintenance. Poor drainage can cause pumping ties and
water pockets that, when ice forms, lead to a heaving roadbed. Water pockets can be drained
with a pipe and drainage ditch or by filling them in with stones or grout. Areas surrounding the
roadbed must be drained by ditches, pipes, or rock drains; and the ballast and ditches must be
cleaned so that water cannot be blocked.