The Swiss Safety Investigation Board (SUST) confirmed its findings this week, confirming its initial suspicion that a broken wheel had led to the derailment of a train in the Gotthard Base Tunnel in mid-August 2023. The wheel failed due to metal fatigue caused by vibrations and started with the cracks in the rim.
The defective wheel was on a carriage belonging to the company Transwaggon AB, a Swedish subsidiary of the Zug-based Transwaggon company.
The affected wheel was manufactured in 2008 and the cracks in it grew over a period of time. However, there is no technology to systematically check for wheel cracks. SUST therefore recommends better visual inspection of all train wheels before trains depart in order to prevent further similar accidents.
SUST also recommends Europe-wide measures related to the defective BA 390 wheel that fractured. Swiss Rail announced that it does not own any wagons with this wheel.
SUST investigation reports (in German)