If flangeways in frogs, crossings, or station platforms become filled with ice, danger of train derailment
is present. While switch heaters may be used at frogs, they obviously cannot be used on highway crossings or
station platforms. The usual remedy is to clean out the ice manually. Salt may be spread on highway crossings
to melt ice but must not be used on turnouts because of the danger of corrosion. Adequate drainage of water
lessens the problem and should be taken care of before the winter season begins.
ICE IN TUNNELS
Ice may become dangerous in wet tunnels, for it builds up in layers on the floors and walls, and heavy
icicles hang from the tunnel roofs. If the icicles are allowed to form and remain, workers may be injured and
equipment may be damaged. Extremely heavy accumulations of ice may derail locomotives and cars. Often it
takes a large force of men to chop away such ice. Providing steep enough drainage ditches to keep water moving
in the tunnel and blocking strong winds from blowing through the tunnel reduce the problem.
In cold winters, ballast freezes, making tamping impossible. Therefore, track must be in proper surface
before winter begins. However, even when a satisfactory surface has been provided, poor drainage may allow ice
to form in the roadbed at isolated points on the line. Water expands while freezing, disturbing the track surface
and heaving the track. Since the track cannot be resurfaced by tamping, other means must be used.
Subparagraphs a and b discuss these methods; subparagraph c. tells what happens after the thaw.
a. Spreading salt or salt water on the ballast lowers the freezing point of water and may help prevent
heaving. But if salt comes in contact with switch points or frogs, it causes corrosion. If the heaved track is not
too much higher than the surrounding track, it may be lowered by removing tie plates. In more severe cases, the
high spots are lowered by digging away ballast; however, this is difficult and expensive.
b. Shimming raises the low areas on each side of the heaved track, providing a smooth surface runoff,
as shown in part A of figure 4.10. The shims used to raise the track are placed between the rail or tie plate and its
tie. The length of runoff depends on the speed