GEFS (FOUNDAMENTALS OF SURVEYING)
CBLAMSIS UNIVERSITY OF THE CORDILLERAS SIMPLE CURVES
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HORIZONTAL CURVES
TOPICS:
1. Steps in determining the best route connecting two termini
2. Horizontal Alignment (simple Curve)
Steps in determining the best route connecting two termini
Reading assignment
Reference: Railroad Curves and Earthworks by Frank Allen (Chapters 1 to 3)
Simple Curves
Simple curve is an arc of a circle use to connect two intersecting tangents in the
horizontal alignment of highways.
Elements of a Simple Curve:
T = Tangential Distance
E = External Distance
M = Middle Ordinate
L = Length of Curve
LC = Length of Long Chord
I = Angle of Intersection (Central Angle)
R = Radius of Curvature
PC = Point of Curvature
PT = Point of Tangency
PI = Point of Intersection (V = Vertex)
D = Degree of Curve
In metric system, the degree of curve, D, is the angle subtended by a 20-
meter arc (arc definition) or a 20 meter chord (chord definition).
Formulas:
๐ = ๐
tan๐ผ
2
๐ธ = ๐
(๐ ๐๐ ๐ผ
2โ1)
๐ = ๐
(1โ ๐๐๐ ๐ผ
2)
๐ฟ๐ถ = 2๐
sin ๐ผ
2
