A major district road with thin bitumenous pavement surface in a low rainfall area has horizontal curve of radius 1400m if desige speed 65kmph
Answers
Answer:
A major district road with thin bituminous pavement surface in low rainfall area has horizontal curve of radius 1400 m. if the design speed is 65 kmph, what should be the superelevation. Solution e where, v=65/3.6
=18.05 m/sec2
g=9.81 m/sec2
R=1400 m e
e= 183.37/13734=0.013 the superelevation required in this case is very small even less than the normal camber of 2% provided for thin bituminous surfacing. The radius beyond which no super elevation is required can be calculated from 0.02
Where e should be taken as the slope of camber which is 2% in this case R=935 m
v So this means that the radius beyond 935 m for the design speed of 65 kmph does not require a superelevation. However, check for safety against centrifugal force at design speed along with the negative superelevation at the outer half of the pavement due to normal camber.
Net transverse skid resistance=-e+f=-0.02+0.15=0.13
Centrifugal ration=v2/gR=0.024
Since the frictional force is grater than the centrifugal force there is no requirement of super elevation at this curve.
Explanation: