Room for improvement in the maintenance of railway support structures

The Safety In­ves­ti­ga­tion Au­thor­ity, Fin­land, has com­pleted the in­ves­ti­ga­tion into the ac­ci­dent in Vesanka on 3 July 2021, in which six wag­ons of a freight train were de­railed. The ac­ci­dent did not cause any per­sonal in­juries or en­vi­ron­men­tal dam­age.

On 19 November 2021, the Safety Investigation Authority issued a notification on the threat of an accident in the section of track between Jyväskylä and Petäjävesi. Structural deficiencies in the support layers and rails of the track that caused a significant risk of an accident were discovered during technical surveys carried out on the section of track.

The accident in Vesanka was caused by a lateral movement of the rails under the train, which resulted in the wagons being derailed.

“In practice, the derailment of the train was caused by a track buckle. It means the thermal expansion of steel when the rail expands due to heat and tries to force the rail loose from its fixture and move it sideways. On the section of track in which the accident occurred, basic renovation work had been done in the summer of 2021, which had weakened the stability of the support layer of the track. The temperatures should have been monitored more carefully during the renovation work than what was done in this case. The support layer did not provide enough support for the rails, especially when several track buckles were found during the summer of 2021,” says Investigator-in-Charge Lasse Laatta.

Laatta further adds: “On tracks with a weakened support layer, the risk of a track buckle is likely to increase in the future due to the climate change, because according to the forecasts, the periods of hot weather will be longer and the amount of rainfall will be larger. The challenges of track maintenance will definitely increase further.”

As a result of the investigation, the Safety Investigation Authority has issued four recommendations for improving the safety of railway traffic and preventing accidents due to track buckles. They are targeted at the Finnish Transport Infrastructure Agency as well as the Finnish Transport and Communications Agency.

“The Finnish Transport Infrastructure Agency has already taken measures regarding the safety deviations discovered during the investigation,” Laatta says.