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Tencin-Theys english summary

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publié le 11 avril 2008

Technical investigation report on the near-collision between two trains on 28 June 2006 at the station of Tencin-Theys (38)

On 28 June 2006, train 885750 (the TER regional train between Chambéry and Grenoble) was stopped in Tencin‑Theys station on track 2, as it waited for the line to be declared clear by a rail maintenance train dispatched previously. Having passed through the station of Pontcharra-sur-Bréda, train 738584 arrived behind train 885750 on the same track. The driver of train 738584 was surprised by the unexpected presence of the other train, but having already slowed down in accordance with the signalling on the line, he managed to stop his train twenty metres from the back of the stationary train.

This incident demonstrated that two trains were located on the same track section at the same time, a situation that contravenes regulations.

This particular line is equipped with a double-track manual block system that does not allow the track to be declared clear at the previous station until the train has passed the semaphore at the next station and the semaphore is closed. Proof that the train has actually arrived at the next station is provided by a treadle actuated by the train.

Four causes were underlined :

- The main direct cause of the incident was human error. Indeed the line was declared clear inaccurately when the rail maintenance train dispatched towards Grenoble departed from the station. This allowed a second train to enter a section of track that was already occupied, without the driver of this second train being notified of the fact,
- The second direct cause was also linked to human error and involved the failure to protect train 885750, which was stopped at the station. When train 738584 reached the approach to the station, its driver did not encounter the protection signal (disc D2) in the closed position and therefore had not prepared to stop safely behind a stationary train,
- The third cause was a lack of organisation on the part of the employees operating the station that morning. The duty station controller for the previous night had not correctly performed the handover to his successor, that is to say, he failed to coordinate the different tasks relating to the safety of railway traffic,
- The fourth cause, which relates to the installations, was the ineffectiveness of the protection systems designed to ensure that track sections are declared clear safely : the safety systems governing the operation of the block system (actuation of a treadle, closing of the semaphore) were bypassed fortuitously, despite the fact that the track was occupied.

Hence, three recommendations were made :

- two calling for modifications to the installation : changing the location of a treadle and modifying the protection signal’s control circuit,
- a third relating to how a team’s work is coordinated by the duty station controller.