Weight
D.
Is a high-quality ballast used under the top ballast where the subgrade is
particularly spongy.
3
15.
Grouting is one way to get rid of a water pocket. To apply this method, you
would:
A.
Construct an intercepting ditch or dike.
B.
Dig trenches under rail joints and fill them with cinders.
C.
Install a French drain in the water pocket.
D.
Inject a cement-water mixture, under pressure, into the water pocket.
3
16.
A stretch of main-line track subject to a heavy volume of high-speed traffic is
to be reballasted, Crushed stone is not available for the job, but several other
kinds of ballast materials are. Your second choice, comparable in quality to
crushed stone, would be:
A.
Cinders.
B.
A sand and gravel mixture.
C.
A good-quality slag.
D.
Pit-run gravel.
3
17.
A typical cross section of an earth and rock cut is shown in sketch:
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