TRANSIT-STADIA or THEODOLITE-STADIA (OBSOLETE METHODS)
H = Ks + C = (stadia interval factor)(stadia interval) + stadia constant
K=f/i
s = upper reading - lower reading
C=c+f
D = (f / i) s + (c + f)
Use this formula if the rod is perpendicular to line of sight (dark blue stadia)
H = (Ks + C) cos α
V = (Ks + C) sin α
Use this formula if the rod is vertically aligned to the ground (light blue stadia)
H = Ks cos2α + C cos α
V = (½) Ks (sin 2α) + C sin α
D=
2
𝐻
2
+ 𝑉
HORIZONTAL CURVE FORMULA
A. CIRCULAR CURVE
1. SIMPLE CURVE
SI units
English
Chord Basis
R = 10/sin(D/2)
R = 50/sin(D/2)
Arc Basis
R = 1145.92/D
R = 5729.58/D
I = 2 tan-1 (T / 2)
T = R tan (I / 2)
E = R [ 1/cos(I / 2) - 1]
M = R [ 1 - cos( I / 2)]
LC = 2R sin (I / 2)
Lc = (π R I)/ 180o
Station PC = Station PI - T
Station PT = Station PC + Lc
Station PT = Station PI - T + Lc
2. COMPOUND CURVE
Station PC = Sta. PI - T1
Station PT = Sta. PC + LC1 + LC2
Station PT = Sta. PI - T1 + LC1 + LC2
3. REVERSE CURVE
Station PT = Station V1 - T1 + LC1 + LC2
Station V2 = Station PC + T2 + LC1
Parallel Tangent
I1 = I2
Diverging/Converging Tangent
I2 = I1 + I
Intermediate Tangent