RAILROAD COXSTRrCTIOX 
321 
which the rails arc spiked. A road of this character will support 
traffic on a very wet bottom better than a dirt grade. 
Brush Ballast. — Spur tracks crossing swamps and muddy- 
places often are ballasted with brush, including swamped tree 
tops, piled 2 or 3 feet high on the grade. Coniferous brush is pref- 
erable to hardwood, but either may be used. The crossties are laid 
Fig. 106. — A Cu,\^Li ul, ^. Lugging Uailiu...; .^^,..1 ready for the Earth 
Cover. Note the use of non-merchantable material for filling depressions 
on both sides of the culvert. Washington. 
on top of the brush and the rails spiked to them. When the track 
has been used a few times the brush ballast flattens out and cross 
poles are then placed between the ties. One man can cut and 
pile brush on from 100 to 150 feet of roadbed, per day, provided 
it can be secured along the right-of-way. 
Culverts. — These are used where the grade crosses very small 
streams, or slight depressions where it is neceesary to have drainage 
from one side of the grade to the other. 
They are ordinarily made by placing logs from 18 to 30 inches 
