Where-
Vmax = Maximum allowable posted timetable operating speed (km/h).
Ea = Actual elevation of the outside rail (mm). Actual elevation, Ea, for each 50-meter track segment in the body of the curve is determined by averaging the elevation for 11 points through the segment at 5-meter spacing. If the curve length is less than 50-meters, average the points through the full length of the body of the curve.
Eu = Qualified cant deficiency (mm) of the vehicle type.
R = Radius of curve (m). Radius of curve, R, is determined by averaging the radius of the curve over the same track segment as the elevation.
Note 1 to paragraph (e)(2): The test procedure may be conducted whereby all the wheels on one side (right or left) of the vehicle are raised to the proposed cant deficiency and lowered, and then the vertical wheel loads under each wheel are measured and a level is used to record the angle through which the floor of the vehicle has been rotated.
49 C.F.R. §299.315