Risk assessment must be improved and the instructions and maintenance of equipment used in transfers must be ensured in special transports in rail traffic

The Safety In­ves­ti­ga­tion Au­thor­ity, Fin­land, has com­pleted the in­ves­ti­ga­tion into the de­rail­ment of a train trans­fer­ring a metro in Oulunkylä on 2 De­cem­ber 2021. The ac­ci­dent oc­curred when a metro that had un­der­gone an over­haul was be­ing towed back to the metro de­pot. The trans­port was car­ried out as rail trans­port. The train set up for tow­ing con­sisted of three units: the lo­co­mo­tive, the metro and a mea­sure­ment car­riage that acted as the brak­ing unit.

A towing adapter as well as a temporary brake pipe installed on the chassis of the metro were used for transferring the metro. In the accident, a malfunction occurred simultaneously in both the towing adapter as well as the coupling of the metro, which resulted in the train breaking up and the locomotive becoming separated from the rest of the combination. The characteristics and installation method of the temporary brake pipe prevented the brakes of the measurement carriage from working, and as a result, the combination of the metro and the measurement carriage collided with the locomotive and the metro axle became derailed. The accident did not cause any personal injuries or environmental damage, but the metro was badly damaged due to the collision and derailment.

A risk assessment had already been made on the transport during the planning stage. When transfer was eventually carried out, it deviated from the original plan. However, the risk assessment was not updated at this stage, and the risks caused by the technical solutions were not identified.

Special transports have not been previously handled as critical to safety, and for instance, the adapters used in transfers have not been included in maintenance programmes and special instructions have not been created for them.

“The same importance should be given to special transports on railways as for normal traffic. The risk assessment of and instructions for these special transports should be emphasised, because they often involve different methods and technical solutions from the traditional transports,” says Chief Rail Safety Investigator Lasse Laatta. “The recommendations we have issued based on this investigation are focused on not only the maintenance and instructions on the technical side, but also the operating methods and practices,” he adds.

The Safety Investigation Authority Finland issues three safety recommendations as a result of the investigation; they are targeted at the Finnish Transport and Communications Agency as well as railway operators. The risk assessment procedures in safety management systems in particular should be addressed during audits. In addition, railway operators should ensure that towing adapters and other auxiliary devices used for coupling are maintained and create instructions for their use.