Permanent Protection Measures
a. In overflow territories, care must be taken to review the adequacy of design, location and construction of
existing drainageways and make appropriate corrections if deficiencies are found. Sufficient waterway
capacity is essential to minimize heading during floods and, if necessary, provisions should be made for
additional relief openings to handle the flow. The impact of runoff from neighboring facilities, existing
and proposed, must also be assessed. Input from applicable local, state, or federal authorities should be
sought in these preliminary drainage assessments.
b. Selection of the optimal permanent protection measure should be done on a site-specific basis and will
depend on many factors, including service requirements, severity and extent of the damage potential,
embankment soil characteristics, and economic considerations. A subsurface exploration of the area in
question, performed during the preliminary stages, can many times generate valuable information and
aid in the selection and design process.
c. In general, depending upon service requirements, a track raise is the best assurance for reliable
operation. Roadbeds subject to severe side erosion can be protected by relocation of the track and/or
channel, or construction of revetments as discussed in Article 3.4.5 and Article 3.4.7, respectively. In
overflow bottoms where either a channel change, installation of additional openings, or a track raise or
relocation do not afford sufficient relief, consideration should be given to facing the downstream side of
the roadbed at least at critical locations with riprap or other suitable means of protection. Covering
erosion-susceptible slopes with a thick vegetative cover can furthermore provide protection by impeding
surface erosion.
d. On light traffic density lines where the aforementioned extensive measures cannot be economically
justified, consideration might be given to anchoring the track to the roadbed, at designated locations
throughout the overflow area, utilizing cable tied to rail, timber pile, or screw anchors driven in the
roadbed. Under these conditions use of a heavy course ballast tends to reduce the incidence of ballast
displacement. When using this last method of protection, the railroad is accepting the risk of traffic
disruption due to flooding and washouts.