Flange climb derailments of railway vehicles during the running at a low-speed occur on sharp curved and twisted tracks. We studied the flange climbing mechanism to clarify and quantify the factors that cause derailments. Regarding this subject, running tests of a passenger vehicle were carried out on a test line of RTRI subsidized by the Ministry of Land, Infrastructure and Transport. The derailments actually occurred under the tests, in which wheel/rail contact forces, the force exerted on the wheelsets, and dynamic behaviors of the vehicle were measured. Moreover, bench tests were performed with roller-rigs to investigate the characteristics of creep force. Based on the test results, this paper proposes a method to assess the safety against vehicle derailments on the curved tracks using the ratio of wheel load reduction as obtained by field running test under the low-speed train operations.

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