Curve is a line of which no part is straight and which changes direction without angles
• Necessarily evil
• Positive impediments for higher speeds
• Necessity arises due to physical and geographical features.
Curve Designation
• Curves are designated by their radii except on IR and US rail roads
• On IR degree of curve for designation
• Radii for calculation
Degree of Curve
Degree of curve is the angle subtended by 30.5 m chord
On IR the curves are measured by versines-which is mid chord offset on 20 m chord
CURVE EFFECT
• Vehicle running at a speed of V in a curve of radius R experiences a
centrifugal force = MV²/R
• Undesirable effects
– Possible passenger discomfort
– Possible displacement of loads
– Risk of vehicle overturning
– Risk of derailment
– High lateral force resulting in
• Curve resistance
• Wear of rail and wheel flange
• Lateral force on track
