CPRR.org Header.lbi" --> Early Standard Gauge Track Spirit Level
for Measuring Rail Superelevation on Curves. In order to help
compensate for the undesired effects of centrifugal force on
trains as they follow curves in the track at speed, the outside
rail on such curves is "superelevated" or raised above the level
of the inside rail on access and main running tracks on which,
in general, the speed limit is 20 miles per hour or more. While
the lower or inside rail holds the established grade of the
track, ballast is added under the ties supporting the upper or
outer rail thereby "tilting" or "banking" the track toward the
center of the arc of the curve. The amount of superelevation
employed is derived by the equation E = CDV2 where: = the
superelevation of the outer rail in inches C = 0.0005 (for
curves less than 3 degrees) or C = 0.0004 (for curves of 3
degrees and above) D = the actual curvature of the track in
degrees V = the maximum allowable speed in miles per hour (Click
on the thumbnails to see the ima