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Les enquêtes techniques

Les Menuires english summary

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publié le 26 février 2020

The event relates to the Granges chairlift located on the skiable part of Menuires.
At 12:21 on 4 April 2016, in overcast and windy conditions in which the anemometers of the Granges chairlift triggered several “strong wind” alerts during the morning, an empty chair swinging in a gust of wind caught the walkway on pylon P10 and fell to the ground.
The chairlift stopped after the cable derailment detector on the pylon was triggered.
After ascertaining that the cable was not derailed and that damage to the cable and pylon balance was limited, a visual surveillance was set up and the lift was restarted at a reduced speed to transport the passengers who were in the other seats to the station. The immobilisation then the recovery of the customers required a total of about one hour.
Operation of the facility was subsequently halted pending the conclusion of the immediate investigations and checks.
It resumed on 9 April up until the end of the season with the agreement of the STRMTG, the State Technical Service in charge of the safety control of ski lifts, with restrictions in relation to wind speed and subject to weekly checks of the condition of the cable.

The investigation showed that the fall of seat no. 13 was due to the impact and the seat becoming attached to the end of the support beam of the steps of pylon P10. The impact was due to the shakiness of the seat under the effect of a strong wind and its protective bubble inadvertently opening. The attachment was due to the absence of an anti-engagement guide at the end of the pylon beam.

This analysis led BEA-TT to make four recommendations on the following matters :

  • the rules relating to the use of the installation when it is very windy ;
  • the information on the strength and direction of the wind provided to the driver ;
  • maintenance of the bubble locking system ;
  • the risk linked to the seats wobbling due to the wind being acknowledged in the gauge rules and standards.