\fdO'^ - Old Forge Coal Mines

RAILROAD LOCATION. 271
second curve; A' = 955.137 ft., the radius of the 6° curve, and
r = G37.27 ft., the radius of U° curve, and D — 26.4 ft. Substituting
these values in the foregoing formula, we have
(955.37 - G37.27) X .82577 - 20. 4
cos V =:
-^
955.37-637.27
0.7428, the cos of 42° 02'.
— =
As the given angle of the second curve is 34° 20', and the
required angle 42° 02', the difference, viz., 7° 42', we must
deduct from the first curve. The distance which we must
retreat on the first curve we determine by dividing the angle
7° 42' by G, the degree of the first curve. The quotient will
be the required distance in stations. Reducing 7° 42' to
7 7
the decimal of a degree, we have 7.7°. -^— = 1-2833 stations
= 128.33 ft.
(790) .This question comes under Problem II, Case 1,
Art. 1423, but the tangent falls within instead of without
the required tangent. Consequently, we must advance the
P. C. C, which will diminish the angle of the second curve
and, consequently, increase its cos. V, the distance between
the given tangents, will, therefore, be positive^ giving us
c 1 ^^
•
formula
U^
99, viz., cos y — -
— ^) cos X -\- D ,
73 (see Art.
K — r
1423), in which x — 3G° 40', the angle of the second
curve; /? = 1,910.08 ft., the radius of a 3° curve; r —
819.02 ft., the radius of a 7° curve, and Z>=32.4ft., the
distance between the tangents. Substituting these values in
the given formula, we have
(1,910.08 - 819.02) X .80212 + 32.4
cos V := -— — =
-^
1,910.08-819.02
.83181, the cos of 33° 43'.
The given angle of the second curve is 36° 40', and the
required angle is 33° 43'. The difference, 2° 57', we must
deduct from the second curve and add it to the first
curve. To determine the number of feet which we must
add to the first curve, we divide the angle 2° 57' by 3, the