This centrifugal force can be
counteracted by the application of
superelevation (or banking), which
effectively raises the outside rail in the
curve by rotating the track structure
about the inside rail. (See Figure 6-6)
The point, at which this elevation of the
outer rail relative to the inner rail is such
that the weight is again equally
distributed on both rails, is considered
the equilibrium elevation. Track is
rarely superelevated to the equilibrium
elevation. The difference between the
equilibrium elevation and the actual
superelevation is termed underbalance