__Minimum horizontal curve radius is
calculated based on the following formula
:__

Where,

= radius defined to the vehicle’s travel path in ft
(m),

= coefficient of side friction, typical 0.13

*V* =
vehicle speed in ft/s (m/s),

*g* is the gravitational constant, 32.3 ft/s/s (9.807
m/s/s), and

*e**
*= number of vertical ft (m) of rise per 100 ft
(m) of horizontal distance.