2024-01-12 20:23:30
Three months of downtime, at least, for line B of the Rennes metro. The second outage in the space of a few weeks. The infrastructure had already remained out of service between November 18 and December 22, 2023. Another incident, which occurred on January 3, again led to the shutdown of operations, this time for at least one quarter. What if it was all the fault of a single nut? This is what a decree from the prefecture, published this Friday, seems to indicate. And this is confirmed by a source close to the matter at Télégramme.
In the decree, we learn in particular that Keolis, the operator of the metro, will not relaunch line B without a lasting solution to prevent the loosening of a nut, located at the level of the bogie, these trolleys which allow the trains to move forward. For its part, the competent State service* also considers that the axle fixing system could require “potential design changes”.
Failures linked to “loosening” of a nut?
Contacted, a source close to the matter confirms this information. And provides further explanations. “The fact that there is a need to change parts on a metro is completely normal,” she emphasizes. Moreover, the trains had reached 200,000 km and were due for an extensive overhaul. On the other hand, what those involved in the case would not have anticipated, the same source details, is that this nut in particular shows fragilities so quickly. And only several months of operation could reveal them. As a precautionary measure, the decision was made to stop traffic and change them on all trains. But, we are told, this would not be a serious problem in itself.
Still according to our information, the first incident on November 18 also had the origin of the unexpected loosening of this nut. A metal element located under a train, held by this sort of large bolt, would have in fact come loose before coming into contact with an electrical bar, fixed to the floor of the tunnel. This is what would have triggered a short circuit then a fire in an electrical room, immobilizing line B for a month.
A “disguisement”?
Regarding the incident of November 18, the decree also mentions the “disguising” of the train which experienced this incident. The word is enough to make you jump: it necessarily brings to mind the term “derail”. “We have to be reasonable,” says an interlocutor familiar with the ongoing investigations. The abnormal vibrations caused by the damage (to which two students testify, editor’s note) were actually recognized as a deguidance by the alert system. But the train did not leave its track, so it is not a derailment in the sense in which we understand it.”
Asked about this term on Tuesday, Siemens Mobility, designer of line B, also refuted it. “On November 18, the system went into security, that’s what’s important,” declared its representative. He also mentioned the defective part, the size of a fist, but without naming it directly. The company could not be reached for comment.
Does the nut have a design flaw, even a minor one? In this scenario, liability – and therefore the bill for repairs – would fall to Siemens. Is it more of a maintenance problem, normal after 200,000 km but not anticipated? In this case, Keolis, network manager and therefore responsible for maintaining the trains, may have to take out the checkbook. This is the challenge of expertise, still ongoing. Hence, undoubtedly, the great caution of those involved in the matter.
* The Technical Service for Ski Lifts and Guided Transport (STRMTG)
1705104843
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