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SETTING OUT - Coggle Diagram
SETTING OUT
INSTRUMENTS
Prism
Nail
Tripod
Rope
Total station
Measuring tape
INTRODUCTION
Opposite to detail survey.
Setting out is to locate the calculated coordinate of the
things to the ground.
Setting-out is a process of transferring planned project to
the ground by using a suitable method.
Setting-out A Circular Curve
Meaning : A process of marking (setting-out) the centre line of a route (road, railway) at chosen intervals
Involves the computations of the deflection angles
from a selected tangent
METHOD
Deflection Angle Method
OBJECTIVE
Setting out is to locate the calculated coordinate of the
things to the ground.
To execute as-built survey upon the completion of the
setting-out work.
Setting-out A Vertical Curve
How?
The reduced level (RL) of chainage points needed are calculated and pegs/markers are driven to indicate cut and fill
Therefore, setting-out data are chainages whose reduced levels represent the finished level (surface of the proposed road)
EQUATIONS
Length of the curve (2 methods)
Based on vertical radial force
Based on the sighting distance (S)
Length of curve (2l) based on vertical radial force; 2L (total length) = ((p+q)*(v^2)) / (100f)
Length of curve (2L) based on the sighting distance (S) - 3 cases are possible
S > 2L
S < 2L
S = 2L
The position of the highest point on the
curve from the tangent point;
x = (2p/ p+q) * L
Transition Curve
How is a transition curve used in road geometric design?
Supposing two straights are connected by a
circular curve
The circular curve is partly replaced by two transition curves at each end (at the beginning and ending sections) as combined curve
Vertical Curves
Needed at intersections of grades or slopes
Crest curve - grade meeting at summits
Grades are represented in terms ratio or percentages;
grade 1:40=2.5%
Sag curve - grades meeting at valleys
Rising grades are written as +ve (e.g.+5%)
and those descending as -ve (-5%)
In vertical curve designs, calculations are based on the algebraic difference between gradients
Gradients increasing in the direction of chainage are given +ve sign and those decreasing are -ve