The correct answer is: D. no compensation
The percentage compensation in gradient for ruling gradient of 4% and horizontal curve of radius 760 m is 0%. This is because the ruling gradient is the maximum gradient that is allowed on a railway line, and the horizontal curve of radius 760 m is within the limits of the ruling gradient.
The ruling gradient is the maximum gradient that is allowed on a railway line. It is the gradient that is used to calculate the maximum speed that a train can travel on the line. The ruling gradient is determined by the following factors:
- The type of train
- The weight of the train
- The adhesion of the train to the track
- The curvature of the track
The horizontal curve of radius 760 m is within the limits of the ruling gradient. This means that the train can travel at the maximum speed that is allowed on the line. There is no need to compensate for the gradient on this curve.
The other options are incorrect because they do not take into account the ruling gradient and the horizontal curve of radius 760 m.