Safety measures against flange-climb derailment in sharp curve-considering friction coefficient between wheel and rail –

To estimate the safety against flange-climb derailments the safety measures based on Nadal's formula have been used in the world. These measures are effective, but the safety margin against flange-climb cannot be estimated quantitively because the actual friction condition between rail and wheel flange cannot be measured by conventional methods. In this paper, the authors propose a new method for the estimation of the friction condition between rail and wheel flange, and using the estimated value of the friction coefficients, a safety measure, the “flange-climb index” (FCI), is proposed. The value of FCI can evaluate the margin for the safety against flange-climb occurrences quantitatively according to the friction conditions.