What is the relationship between speed, turning radius, and track cant? What are the cant excess / deficiencies specifications for IR tracks?
Super-elevation, or cant, is provided to counteract the centrifugal tendency of trains on curves. On a canted curve (where the outer rail is higher than the inner one of the curve), the weight of the vehicle provides a component that counteracts the centrifugal tendency. Cant excess refers to the condition where the cant or superelevation is too much for the permitted speeds on the curve, while cant deficiency refers to the condition where the track is not canted enough for the speed of the trains. On BG track, cant excess and cant deficiency tolerances are 75mm. In special cases, cant deficiency can be as high as 100mm on sections with speeds of over 100km/h on ‘A’ and ‘B’ category routes. Maximum cant is 165mm on ‘A’ and ‘B’ routes, and 140mm on ‘D’ and ‘E’ routes. The formula relating the maximum speed on a curve with the cant and cant deficiency is: Max. speed = 0.27 * sqrt((cant + cant deficiency) * radius) where the cant and cant deficiency are in mm, the radius of the curve is i
