Swiss railways have long taken a leading role among European networks in promoting measures to reduce noise generated by passing trains, especially freight trains. Passenger trains, in contrast, have a significantly lower acoustic impact as they replaced traditional cast-iron brake shoes with disc brakes some time ago, similar to those used in road vehicles. It is particularly during braking that trains generate the most noise disturbance, especially freight trains made up of long compositions of wagons and therefore numerous braked axles. For this reason, cast-iron brake blocks (GG) have been banned from the Swiss rail network since 2020. In their place, alternative solutions such as brake blocks marked with the initials LL (for low-noise-low-friction) have been developed. These LL blocks have seen widespread use in Europe, largely driven by the choices made by Swiss railways.
It may seem paradoxical, but it is now Switzerland that is taking a step back. SBB will gradually discontinue the transport of freight wagons equipped with LL brake blocks, with most of them to be withdrawn from service by the end of 2025. Why such a drastic decision, which almost takes the shape of a plot twist? In truth, the reconsideration is not entirely sudden, as numerous incidents involving LL brake blocks causing overheating of wheel discs and potential damage to the discs have been known for some time.
But the final blow came after the serious accident in August 2023 inside the Gotthard Base Tunnel, when a freight train derailed, causing damage to the infrastructure estimated at no less than 150 million euros and prompting a long closure of the tunnel for repairs. On 2 June 2025, the final report into the causes of the accident was presented by the Swiss Safety Investigation Service (SISI), which identified a broken wheel on one of the wagons involved as the source of the incident. The SISI report confirms the role played by LL brake blocks in what occurred. For this reason, the federal railways have decided to speed up the decommissioning plan for wagons equipped in this way.
Of course, Switzerland alone would have a limited impact, which is why SBB is urging European authorities, such as the EU Agency for Railways (ERA), to take swift action. The federal railways believe that both in Switzerland and across Europe, the use of freight wagons with LL brake blocks should be restricted or even banned. That there were problems with these wagons is also known to other railway administrations.
Does this mean going back to square one, with cast-iron blocks so heavily criticised for their acoustic impact? Not necessarily, as other alternatives exist on the market, although less widespread than the LL blocks. These include composite material brake blocks (K), which now represent the standard in Switzerland, replacing the previous system. K blocks are certainly preferable for their properties, but they come with a less favourable economic profile, as their use requires changes to the entire braking system downstream of the distributor, affecting all components from the cylinder to the linkage and block holders. Nonetheless, this path seems necessary to reconcile reduced noise impact with safety in freight transport.
Piermario Curti Sacchi
