The correct answer is: C. higher of (A) and (B).
The length of a transition curve is determined by the allowable rate of change of centrifugal acceleration and the rate of change of super elevation. The allowable rate of change of centrifugal acceleration is the maximum rate at which the centripetal force can change without causing discomfort to the driver. The rate of change of super elevation is the rate at which the road surface is raised on the outside of the curve to counteract the centrifugal force.
The higher of (A) and (B) should be taken because it will provide a smoother transition for the driver and reduce the risk of accidents.
Option A: based on allowable rate of change of centrifugal acceleration.
The allowable rate of change of centrifugal acceleration is the maximum rate at which the centripetal force can change without causing discomfort to the driver. The centripetal force is the force that pulls the driver towards the center of the curve. The allowable rate of change of centrifugal acceleration is determined by the driver’s comfort level and the type of vehicle.
Option B: based on rate of change of super elevation.
The rate of change of super elevation is the rate at which the road surface is raised on the outside of the curve to counteract the centrifugal force. The super elevation is designed to keep the driver’s tires in contact with the road surface and prevent them from sliding. The rate of change of super elevation is determined by the radius of the curve and the speed of the vehicle.
Option C: higher of (A) and (B).
The higher of (A) and (B) should be taken because it will provide a smoother transition for the driver and reduce the risk of accidents. A smoother transition will reduce the risk of the driver losing control of the vehicle. A reduced risk of accidents will improve safety.