Length of Transition Curve (Ls) | Horizontal Transition Curves
Length of Transition Curve (Ls) | Horizontal Transition Curves
INTRODUCTION :
Horizontal Transition Curves:
Transition curve is a curve in plan which is provided to change the horizontal alignment from straight to circular curve gradually means the radius of transition curve varies between infinity to R or R to infinity.
Length of Transition Curve (Ls)
The radius of a transition curve varies from infinity to the design radius or vice verse. The length of the transition curve must fulfil some requirements. It is designed to fulfil the following three conditions.
A. Rate of
Change of Centrifugal Acceleration
B.
Rate of
Introduction of Superelevation
 |
 |
Lc = EN = e(W + We)N wℎen eavenent is rotated about centrel ine 2 2
Lc = EN = e(W + We)N wℎen eavenent is rotated about inner edge
C. Empirical formula
|
v |
= |
Design speed (m/s) |
|
C |
= |
Rate of change of centrifugal acceleration (m/s3) |
|
R |
= |
Radius of horizontal curve (m) |
|
V∗ N |
=
= |
Design speed (km/h) Rate at which superelevation is
introduced (150 – Normal, 100 – Built up areas and 60 – Hill
roads) |
|
E |
= |
Amount of Superelevation or Total raising
of pavement (m) |
|
e |
= |
Rate of superelevation |
|
W |
= |
Width of pavement (m) |
|
We |
= |
Extra width of pavement (m) |
Note:
Shift of
transition curve is given by =
COMMENTS