Private Swiss train operator BLS says it is putting in place immediate measures after the Swiss Transportation Safety Investigation Board (STSB) discovered unusual braking behaviour in the MUTZ trains.
After receiving this information, BLS implemented several measures to ensure the trains can operate safely. It is working with the vehicle manufacturer, Stadler, and the STSB to determine the cause of the problem.
On 31 December 2020 a MUTZ EMU collided with a second MUTZ (Stadler KISS) at a speed of 23km/h. The two trains were to be coupled together. Both vehicles sustained damage costing around 365,000 euros each. As is required, BLS reported the incident to the Federal Office of Transport and the Swiss Transportation Safety Investigation Board. It has also established a task force to examine the event.
During the investigation, the STSB discovered an unusual braking behaviour during poor rail conditions. This occurred during test trips with a MUTZ vehicle in early February 2021. A comparison was also made with a few similar events between 2013 and 2020, which did not cause any damage and which were also reported by BLS to the FOT and / or STSB. Based on these investigations, the STSB will publish an interim report with safety recommendations today.
BLS started introducing preventive measures in January: train drivers have been instructed to reduce their speed sooner and to a greater extent when approaching signals and other stopping points. The routine brake checks in the maintenance depots have also been intensified. The MUTZ will be replaced by a different vehicle for the S6 service between Bern and Schwarzenburg from 1 March 2021. The reason for that is that these immediate measures cannot be implemented in full on this route. BLS has informed the Federal Office of Transport of these measures.
BLS reported the unusual braking finding from 31 December to Stadler right away. All parties (BLS, Stadler, STSB) are performing an in-depth analysis of the findings to date to get to an understanding as to the cause as soon as possible.
The unusual braking behaviour has always occurred under the following conditions: when the trains are travelling very slowly, when the weather is wet and temperatures are close to freezing – the poor wheel-rail contact has led to insufficient braking under these conditions, causing a longer braking distance.
Stadler currently believes that this sub-optimal braking is caused by one of the train’s three braking systems. The remaining two are working as they should. This means the fast braking systems can be deployed at any point so that braking distances can be adhered to in wet and dry track conditions. Stadler therefore believes it has fulfilled its requirements and has deemed the vehicles safe.
BLS currently has 39 MUTZ trains. They have been in service since 2012. Every MUTZ electric multiple unit performs more than 500 braking events every day.
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