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….