ABSTRACT
Three derailment accidents occurred on the Esashi Line in 2012–2014 and in order to find the causes of these accidents JTSB carried out train running tests and numerical simulations by SIMPACK. The results of the tests and the simulations showed the series of accidents were caused by multiple factors, such as “insufficient damping of bolster dampers of freight wagons”, “partly large track irregularities for freight train running” and “unbalance mass and rather high gravity center of freight loading”. These factors are common, but the contribution of each factor is different in each accident. And by additional analyses it is found that “medium loading” condition of wagons increases the rolling resonance due to insufficient damping of bolster dampers in such region, and the rolling angle of the 3rd wheelset is increased due to the torsional flexibility of the wagon body compared with the 1st wheelset of the freight wagon.
