Raising the outside rail tilts the train into the curve so gravity balances part of the outward force, letting trains run faster with less wear on the high rail. Track engineers pick an elevation that suits the speeds of the line's traffic, which is a compromise when fast intermodals and slow coal trains share the same curves. Too much elevation for the actual speeds makes slow, heavy trains grind away the low rail.
There's 4 inches of superelevation in that curve, so the slow coal drags are eating up the low rail.
Also heard as
- elevation
- cant
- super
Related terms
Gauge
The distance between the inside faces of the two rails, 4 feet 8.5 inches on standard-gauge track.
Ballast
The bed of crushed rock under and around the ties that holds the track in line and drains water away.
Drag
A slow, heavy, low-priority freight train, often of bulk loads or empties.
Stack train
An intermodal train carrying shipping containers stacked two high in well cars.