\fdO'^ - Old Forge Coal Mines

RAILROAD CONSTRUCTION. 293
(896) See Art. 1 536 and Fig. 458.
(897) The height of embankment is 21 ft. ; the culvert
opening, 3 ft. in height, and the covering flags and parapet
each 1 ft. in height, making the top of parapet 5 ft. above
the foundation. In Fig. TO the angle B A L is 75° and
represents the skew of the culvert. Drawing the line A D
at right angles to the center line A C^ we have the angle
BAD= S)(f - 75° = 15°. If the culvert were built at right
angles to the center line,
the side distance A D from the
Fig. 76.
center line to the end of the culvert would be as follows:
21 ft. - 5 ft. = 10 ft. 10 ft. X li = 24 ft. Adding 1.5 ft.,
and, in addition, 1 in. for each foot of embankment above
the i. parapet, e., 10 in., or 1.33 ft., we have 24 -|- 1.5 + 1 33 =
20.83 ft. Adding 8 ft., one-half the width of the roadway,
we have 20.83 + 8 = 34.83 ft. = A D. At D erect the perpendicular
DB. In the right-angled triangle A D B, we
'
'
have cos A — i- -j—n, e., cos 15° = .'
A. B A. L)
; whence, .90503 =
•^^•^^^
AB .90593
(898)
and ^^ = 4t^, = 30.00 ft.
See Art. 1541.
Ans.
(899) See Art. 1541 and Fig. 402.
(900)
(901)
See Art. 1542.
See Art. 1544.