What three elements are required to determine proper elevation in a curve?

To determine the proper elevation in a curve, it is essential to consider actual elevation, cant deficiency, and degree of curvature.

Actual elevation refers to the height of the track at the curve compared to the adjacent straight track. Proper elevation helps in counteracting the lateral forces that act on a train when going through a curve.

Cant deficiency is the amount of cant (or bank) that needs to be applied to the track to balance the lateral acceleration experienced by the train. It is important to consider cant deficiency when determining how much elevation is required, especially in cases where the track cannot be fully elevated due to design constraints or other engineering factors.

The degree of curvature gives an indication of how sharp the curve is. This is crucial because more sharp curves necessitate more elevation to ensure trains can navigate them safely and comfortably without excessive lateral forces that could lead to derailment or discomfort for passengers.

These three elements are therefore integral in ensuring that the elevation on a curve is adequate for safe and efficient train operation, making this the correct choice.