# What will be ruling minimum radius for horizontal curve of NH (National Highway) in plain terrain? (Assume ruling design speed = 127 km/h, minimum design speed = 80 km/h, rate of super elevation e = 0.05 and coefficient of friction = 0.05)

What will be the ruling minimum radius for horizontal curve of NH (National Highway) in plain terrain? (Assume ruling design speed = 127 km/h, minimum design speed = 80 km/h, rate of super elevation e = 0.05 and coefficient of friction = 0.05)

### Right Answer is:

1270 m

#### SOLUTION

If velocity is in KMPH then Super Elevation formula:-.

**e + f = V ^{2}/ 127R**

Where,

e = rate of Super elevation = 0.05

V = velocity = 127 km/h

f = lateral friction factor = 0.05

R = radius of circular curve in meters.

0.05 + 0.05 = (127)^{2}/127R

**R = 1270 m**