For the data provided in Problem 15-1, determine (a) minimum radius of horizontal curvature, assuming a superelevation rate of 8%, (b) minimum length of crest vertical curves, and (c) minimum length of sag vertical curves, using the rate of vertical curvature method, when joining two segments at maximum grade.
What will be an ideal response?
(a) Find the minimum radius
R = u2 / [ 15(e + fs)]
R = (302/15) (1/(e + fs))
R = 60 / (emax + fs)
Assuming e = 0.08 and fs = 0.20
Rmin = 60 / (0.08+0.20) = 214 ft
(b) Using Equation 15.12, L= kA
From Table 15.4, K = 19
L = 19 (10 – (–10))
L = 380 ft
(c) Using Equation 15.12, L = kA
From Table 15.5, K = 37
L = 37(10 – (–10))
L = 740 ft
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