Interface - The Journal of Wheel/Rail Interaction

CURVE SUPERELEVATION

Curve Superelevation: Problems and Solutions (continued)

Curve speed restrictions and siding entrance/exit locations might create situations where trains can’t make timetable speed due to operating conditions. Which speed do you use in the formula?

Determining the correct amount of “super” is not as easy as it seems at first blush. And in today’s world of 286,000-pound cars, and high-center-of-gravity cars, the consequences of improper elevations are severe. These consequences can range from low rail spalling, increased curve elevation, rail cant, and at its worse, an increased risk of derailment (see figures 1, 2, and 3). In the past several years, Rail Sciences has investigated numerous derailments where curve elevation was a significant, if not primary, factor in the derailment causation. One particular problem that we have noticed is the cascading of medium-tonnage secondary lines to short line operators. The original “Big” railroad might have operated the line as class 3, where the new shortline operator decides to downgrade to Class 2, or even Class 1 speeds. Thus, the shortline operator is saddled with numerous curves elevated for 40 mph when unit coal trains struggle down the track at 10 mph.

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