a. Stone, slag, or screened-gravel ballast. To clean stone, slag, or screened-gravel ballast,
follow the steps given here.
(1) Remove shoulder ballast (the ballast from the ends of ties outward from track)
down to subgrade.
(2) Remove ballast from cribs (the space between ties) down to bottom of ties.
(3) Remove ballast from the space between tracks down to 6 inches below bottom of
ties or down to subgrade if the ballast below the ties is less than 6 inches deep.
(4) Clean all ballast removed, using ballast forks or screens.
(5) Replace the cleaned ballast and add any new ballast needed to achieve the
required ballast section.
b. Pit-run gravel or cinder ballast. In cleaning pit-run gravel or cinder ballast, follow
(1) Remove all ballast except that directly under ties.
(2) Dress the subgrade.
(3) Add new ballast and raise track as required.
(Railway Track Maintenance II
explains the procedure in more detail. )
c. Mechanical cleaning. In recent years, many civilian railroads have found the cost of
cleaning long stretches of ballast by the manual methods given in subparagraphs a and b to be
prohibitive because of the tremendous labor requirements. The civilian lines have resorted to
mechanized methods for cleaning ballast. One type of machine they use moves along the track
digging up shoulder or between-track ballast, screening it, and replacing it. However, the ballast
cleaner does not remove or screen the crib ballast. One widely held theory that the crib ballast is
eventually replaced by the shoulder or between-track ballast in tamping seems supported by the
success of mechanized ballast cleaners. The initial cost of the machines is high, and they must
be kept in constant use to justify the investment.
d. Frequency of cleaning. Actually inspecting how badly the ballast is contaminated is
the only way to determine the frequency of cleaning. However, experience shows that tracks in