Excerpt from Ensco (self-proclaimed leading provider of railway safety technologies throughout the world) article entitled: "Keeping Your Trains on the Track – Strategies for Preventing Derailments"
Gage Widening and Rail Rollover
The problems that can be encountered with excessive wheel/rail interaction forces are not limited to wheel climb scenarios. For instance, if the lateral force generated by the flange contact between the wheel and the rail is relatively high, this force can cause lateral rail displacement. This rail displacement produces what is known as gage widening and can lead to a wheel/rail separation as shown in Figure 2.
Rail rollover, as shown in the left side of Figure 3, is one of the most common sources of accidents especially when the vehicle travels over the spiral transition between tangent, or straight, track and the full body of a curve.
The critical value of L/V for rail rollover is approximated by the ratio D/H with D and H defined as per the illustration on the right side Figure 3. If the moment generated by the lateral force is higher than the moment generated by the vertical force, the rail can rotate about its corner.
Full article is at http://www.ensco.com/News-Media/pressre ... rticle=128
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