When a geotextile fabric is used, there should be a minimum of 12 inches of
ballast between the bottom of the ties and the fabric.
Drainage. Water is a principal influence on soil stability in
roadbed, subgrade, and slopes. Control of surface and subsurface water is one
of the most important factors in railroad design. For design guidance, see
AREA Manual, Chapter 1, Part 1, Section 1.2.4, Drainage; Part 3, Natural
Waterways, Part 4, Culverts; NAVFAC MIL-HDBK-1005/2, Hydrology; and MIL-HDBK-
1005/3, Drainage Systems.
Monuments. Right-of-way monuments should be reinforced concrete
posts (or similar) 6 inches square, 4 feet long, and embedded 3 feet in the
earth. The specification for monuments from the Department of Transportation
in the state where the work is being done may be used where appropriate.