Bridges, tunnels, interlocking plants, and certain other rail-way structures pose special maintenance
problems and alter normal maintenance procedures. And when demolition damages the track and structures of a
railroad, rehabilitating them changes the usual maintenance procedures. The problems with structures and the
rehabilitation of demolished rail lines are discussed in separate sections of this chapter. The third and final
section explains the management of maintenance-of-way activities by track maintenance men.
Section I. Typical Examples
The track maintenance procedures most commonly used are those presented in the first four chapters.
However, procedures must be changed or adapted when special or unusual problems occur. A common sense
study of each new maintenance job usually suggests the needed variations and why they are necessary. Some
typical examples of special problems follow.
The minimum clearances which must be observed in tunnels limit the maintenance operations in them.
No change in a minimum clearance can be made without approval from a higher authority (RT 670, par. 1.8). For
instance, an out-of-face track raise could not be made in a tunnel without endangering the height clearance of
trains passing through the tunnel. Similarly, if a track curves in a tunnel, it cannot be relined on a different curve
since this would reduce side clearance. A close check must be maintained to insure that traffic has not disturbed
track alinement to the point of endangering side clearance. These restrictions apply to bridges passing over
railroad tracks and retaining walls near tracks as well as to tunnels.