TOPIC 4TOPIC 4CURVESCURVES
CURVESAt the end of the unit you should be able to :- Explain the basic concept of curves. To identify the terminologies of curves. To differentiate between circular curves,
transition curves and vertical curves. Explain the methods of setting out circular
curves. Calculate setting out of circular curves,
transition curves and vertical curves. Apply the method of setting out of a circular
curves and transition curve.
ROAD CONSTRUCTION
RAILWAY CONSTRUCTION
RESERVOIR CONSTRUCTION
DAM CONSTRUCTION
RAILWAY CONSTRUCTION
BUILDING CONSTRUCTION
INTRODUCTION
PURPOSE
is a continuation of the straight lines and curves with a radius of a fixed or variable.
to connect a straight line through the point of intersection () which lies between two straight lines to allow the movement to reverse slowly in the horizontal and vertical directions.
•Physical state of hilly land, swampy.•Connecting the exit or entrance as the exit roads 'toll‘,•Avoiding the position of the details remain, such as building mosques, cemeteries.•Safety of road users in order to travel more comfortable and secure.
Reasons for curves construction:
Differentiate Between Circular Curves, Transition Curves and Vertical Curves.
Definition
Purpose
TypesGeometr
ySetting out method
Curves of constant radius required to connect two straights set out on the ground.
The curves are designed and built to connect the straight lines with circular curves
The curves are designed and made to join two different straight slope.
CURVES - DEFINITONHorizontal curves Horizontal curves Vertical curvesVertical curves Transition curvesTransition curves
For the convenience of road usersTo connect the straight lines with a horizontal curve
To avoid the situation where a sudden change in the vehicle entering the curve from a straight round
To avoid the situation where a sudden change in the vehicle when it starts down the road after climbing a hill or otherwise.
CURVES - PURPOSE
Horizontal curves Horizontal curves Vertical curvesVertical curves Transition curvesTransition curves
CURVES - TYPES
-Circular curves-Transition curves-Compound curves-Reverse curves
None Crest curvesSag curves
Horizontal curves Horizontal curves Vertical curvesVertical curves Transition curvesTransition curves
The parabola has the desirable The parabola has the desirable characteristics ofcharacteristics of
(1)(1)a constant rate of change of a constant rate of change of slope, which contributes to slope, which contributes to smooth alignment transition,smooth alignment transition,(2)(2)ease of computation of ease of computation of vertical offsets, which permits vertical offsets, which permits easily computed curve easily computed curve elevationselevations
T1 T2T1 T2Crest curvesCrest curves
T1 T2T1 T2Sag curvesSag curves
TT11 TT22
δδ
θθ
II
OO
PP RR
CURVES - GEOMETRYHorizontal curves Horizontal curves Vertical curvesVertical curves Transition curvesTransition curves
Offset From The Tangent line
Offset From The Long chords line
Deflection angle method
Sub chords line method
Wacky turnSetting out the transition curves from T1 to T2 Setting out the transition curves from T4 to T3Setting out the circular curves from T2 to T3
None
CURVES – SETTING OUT METHOD
Horizontal curves Horizontal curves Vertical curvesVertical curves Transition curvesTransition curves
Circular curves - types
R2
R2
RR
R1
R1
R1
R2
End of sub -topic•Continued….