 On 21 February 2007 , a Class 73 derailed after hitting an avalanche between Hallingskeid and Myrdal on the Bergen Line . The accident raised questions about the class 's abilities to handle hard snow , such as in avalanches . In particular , a DNV report from 1999 had shown that the train could act as a sled , lose contact with the tracks and slide on top of the snow . A former NSB employee who worked with route planning , stated that a locomotive @-@ hauled train would be better suitable for such situations , because more of the weight is located at the front of the train , and it will therefore plow instead of slide . The National Rail Administration said that they took extra precautions for the Class 73 trains and that during snowfall they would run a snow @-@ clearing unit ahead of all Class 73 runs . NSB stated that they would consider the possibility of reverting to conventional trains , but that unless new information could shed light on the situation , they would retain use of the Class 73 trains . 
