Tignes english summary
On Saturday 3 December 2011, at 15.49 at Tignes, in Savoie, the first seven downline wheels of the trolley on car 2 of the Grande Motte cable-car derailed. After hearing an abnormal noise as the car passed the intermediate pylon, the car operator – who was taking five passengers down to the lower station – stopped the cable-car. Car 2 came to a halt 116 metres after this pylon, whereas car 1 – which was going up on the other cable at the same time with 40 passengers on-board – stopped 418 metres after the lower station.
After having determined that car 2, which had derailed, could not be moved, the operator decided at 16.25 to evacuate the passengers from the two cars. These evacuations were completed some four hours later for car 2 and nearly seven and a half hours later for car 1.
The derailment of the trolley of car 2 of the Grande Motte cable-car was caused by the separation of the scraper attached to the front of the downline inner sheave train of this trolley in order to remove any ice that may form on the carrier cable. This scraper, which had become separated about 3.55 metres upline of the intermediate pylon, slipped under the first wheel of the sheave train, shifting it to the left while forcing it off the carrier cable. Six other wheels downline of the trolley then derailed shortly afterwards, particularly owing to the effect of the friction and shocks that occurred when the car passed the intermediate pylon.
The difficulties that the operator then had evacuating the passengers from the two cars were, in part, due to the implementation – as stipulated in the rescue plan – of the RG10 descender systems, the limits of use of which had not been identified and which became blocked owing to the ice and frost resulting from the weather conditions that were difficult but, nonetheless, reasonably foreseeable in winter at an altitude of more than 3,000 metres.
In view of the above, BEA-TT made three recommendations concerning :
- for the first one, the design, maintenance and monitoring of the scrapers equipping the trolleys of cable-cars ;
- for the other two, the reliability of the ski-lift evacuation plans.
Furthermore, BEA-TT invites the operators of ski-lifts that function without a car operator and that are not equipped with an automatic shutdown device in the event of derailment of one of the cars to fit them with an alarm system such as, for example, the display of an emergency phone number or an alarm signal that can be activated by passengers in the event of an operating problem.
It also emphasised that ski-lifts can only be kept in operation when the weather conditions are difficult if, under those conditions, the passengers can be evacuated in complete safety in the event of an incident, particularly regarding the risk of hypothermia