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La Plagne english summary

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publié le 26 février 2020

The accident concerns the "Télémétro" cable car which connects the two resort villages of Plagne Centre and Aime 2000 on the skiable area of la Plagne.
On Thursday 12 January 2017 at 21:04, it was snowing heavily. While the cabin descending from the cable car went to the right of the pylon P2, the carrier cable escaped from its support at the head of the pylon. It became stuck in the traction cable’s support wheels, located underneath. The cab derailed and stayed balanced on the cable. The installation stopped automatically by triggering an overlapping safety alarm for the traction and carrier cables.
The driver didn’t realise that the cab and the cable had derailed. He tried to restart several times to take the two cabins back to the station, and shunted all of the installation’s security measures to do so. It was not until more than an hour later, following the arrival of the on-call electrician, and after further unsuccessful attempts at movement, that the line was recognised and that the derailment was identified.
They decided to evacuate the five passengers present in the cabs. This evacuation was completed at 0:55. The passengers suffered no injuries.
The Télémétro was then stopped for five weeks to repair the damaged parts of the cab and the pylon. It was up and running again on the 21 February 2017. The operator then took several measures to reinforce safety concerning the monitoring and the operating conditions of the installation. They also initiated a call for projects to modify the design of the cable car.

The immediate cause of the derailment is the attachment of a part of the car carriage to a part of the pylon P2. The movement in these two parts becoming attached laterally drove the carrier cable from its support.
The original cause of the attachment of the two parts was the lateral offset of the suspension cable at the entrance of the pylon, made possible by the presence of ice in the bearing housing of the cable, as well as by the geometric misalignment of the support casing.
Several factors contributed to this accident :

  • design of the vehicle and pylon presenting a risk of derailment in case of ice accumulation ;
  • the fact that on that evening, the de-icing instructions for the suspension cable support at the top of the pylon hadn’t been applied to avoid this risk ;
  • the slightly angled positioning of the cable supports on the pylon with respect to the axis of the cable car.

Immediately after the derailment, the driver made several attempts to restart without any precaution, shunting all the security systems, thus running the risk of doing more damage, the consequences of which could have been serious. He didn’t identify the causes of the emergency stop before restarting the installation.
The organisational and human factors explaining this risky behaviour relate to the lack of training, already observed on other cable cars, and the lack of instructions detailing the checks to be performed for rigorous safety management of this type of incident.

The BEA-TT issued two recommendations relating to the derailing. They concerned :

  • handling the Telemétro derailment risk by redesigning the cable car on the cabins and pylons ;
  • checking how the derailment risk for all cableways with similar design to Télémétro is handled, by ensuring the sturdiness of the suspension cable support safety on the pylon heads.

The BEA-TT issued a recommendation and an invitation relating to the organisational and human factors regarding the post-derailment operations : They relate to :

  • the provision of a formal safety instruction to Télémétro operators specifying the checks to be made before and after shunting a security system ;
  • carrying out an assessment of the effects produced by the new regulations applicable on 1 October 2017, on the training of drivers and, in the event of a deficit, the evolution towards the requirement of a driving clearance for cable car drivers.