New criteria for flange climb derailment

New flange climb derailment criteria are proposed based on tests and simulation results using the track loading vehicle (TLV) and NUCARS simulation model as performed by Transportation Technology Center, Inc. (TTCI), a subsidiary of the Association of American Railroads (AAR). The proposed criteria include 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 milliseconds, 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.