Angle of attack and distance-based criteria for flange climb derailment

New flange climb derailment criteria are proposed, which include both a single wheel lateral to vertical (L/V) force ratio limit and a L/V distance limit. Results presented here indicate that both the single wheel L/V ratio limit and the L/V distance limit are strongly dependent on wheelset angle of attack. The existing L/V time duration criterion of 50 millisecond, which is currently used during track worthiness tests in North America, is evaluated against the proposed new L/V distance limit and is shown to be unsafe for large angles of attack and higher speeds. The influence of parameters such as wheel/rail friction coefficient and longitudinal force on the proposed derailment criteria is discussed in the paper.