Summary in English

On 24 February, 2024, a freight train derailed at Vassijaure station on the Malmbanan train route between Narvik in Norway and Kiruna. The train consisted of two locomotives and 62 unloaded wagons. There were no injuries, but damage to infrastructure and vehicles.

There was a strong south-easterly wind from the Norwegian border and further into the Swedish side. The air temperature was above zero, while the ground was below freezing. This caused the wind to move wet snow, which became packed and froze on the ground.

The train had to wait outside Vassijaure for almost an hour because of maintenance work at the station. The driver stopped the train inside two snow galleries, where it was largely protected. During the wait, the driver made several short movements of the train. Because of a hole in the wall of one of the snow galleries, together with the strong wind, it became possible for snow to drift in and become packed on the track underneath the wagons.

As the train continued, the packed snow lifted some wheels and wagons off the rails. The track was in a curve and lateral forces caused the wheel flanges to simultaneously climb over the inner rail and derail. The derailed axles and wagons rolled with the train for 1.2 kilometers into Vassijaure station before the derailment worsened and the train was forced to a stop.

Causes of the accident

The direct cause of the derailment was that packed snow, together with lateral forces, caused wheel axles with low axle load to lift and flanges to climb over the rails.

A contributing factor was that strong winds, in combination with the temperature difference between air and ground, formed snowdrifts of hard and packed snow on the track.

A further contributing factor was a hole in the wall of snow gallery 14, which enabled snow to drift onto the track and underneath the wagons.
The long pause of the train allowed yet more snow to drift underneath the wagons.
At inspections, the hole in the wall of snow gallery 14 had not been noted and repaired.
The south-easterly wind may have contributed to increased drift and formations of snow in gallery 14.

Operational rules and routines had not dealt with the risks of severe snowdrift formation underneath stationary wagons of low axle weight.

Safety recommendations

The Swedish Transport Administration (Trafikverket) is recommended to:
• Review the guidelines and routines for the construction and maintenance of snow galleries in order to protect the track against severe snowdrift formations.

The Swedish Transport Administration (Trafikverket) is recommended to cooperate with the railway undertakings that operate Malmbanan, to:
• Continue to assess how routines can be developed and measures taken with the aim of reducing the risk of train derailment in connection with low axle load and severe snowdrift formations.