Gotthard Base Tunnel gets derailment detectors
SWITZERLAND: SBB has installed derailment detectors at around ten locations on the approaches to the Gotthard Base Tunnel, lifting a speed restriction that has been in place since the tunnel reopened in September 2024.
The detectors went live on the night of 10–11 May, installed before the portal crossovers where passenger and freight trains pass through high-speed switches at line speed.
SBB says the detectors can limit the consequences of a derailment but cannot prevent one — and that only improved wagon maintenance and a change to liability law can do that.
What detectors do — and what they cannot
The sensors are the only proven infrastructure-side technology for detecting a derailment. Their purpose is to trigger an emergency response fast enough to prevent a collision between trains — not to stop a derailment from happening.
The 2023 derailment, which closed the tunnel for more than a year and cost SBB approximately CHF 150m, was caused by a wheel fracture on a freight wagon. Preventing a repeat requires detecting wheel cracks before they cause a failure — which happens during maintenance, not on the track.
The liability gap SBB wants closed
Under current rules, if a wagon defect causes an accident, the railway undertaking transporting the wagon is liable — not the wagon keeper. SBB argues this gives wagon keepers too little incentive to invest in safety beyond the legal minimum.
Switzerland’s Federal Office of Transport has introduced new maintenance requirements: minimum wheel diameters, more frequent distance-based inspections, and improved wagon checks. Wagon owners and maintenance providers have until 31 December 2026 to comply. The regulations have been widely contested by wagon owners.
SBB is calling for liability legislation to be amended — a structural change that would require action beyond Switzerland’s borders, given that the freight wagons passing through the Gotthard are registered across Europe.
One problem solved, one still open
The detectors are now in place. The speed restriction is lifted. The liability question is not resolved — and until it is, SBB says the incentive structure governing freight wagon safety remains unchanged.