Method 1. Superelevation and side friction are directly proportional to the degree
of curve or the inverse of the radius.
Method 2. Side friction is used to offset centrifugal force in direct proportion to
the degree of curve, for curves up to the point where fmax is required. For sharper
curves, fmax remains constant and e is increased in direct proportion to the increasing
degree of curvature until emax is reached.
Method 3. Superelevation is used to offset centrifugal force in direct proportion
to the degree of curve for curves up to the point where emax is required. For sharper
curves, emax remains constant and f is increased in direct proportion to the increasing
degree of curvature until fmax is reached.
Method 4. Method 4 is similar to method 3, except that it is based on average
running speed instead of design speed.
Method 5. Superelevation and side friction are in a curvilinear relationship with
the degree of curve (inverse of radius), with resulting values between those of
method 1 and method 3.