Mont Blanc gondi cable breaks

TomWhiteTomWhite expert
in NELSAP Forum Posts: 581

This looks like a pulse gondi. When I started the article, I
thought, workers cut the cable rather than waiting for the ice to melt to free
the cable. But no, the storm cut the cable, in two places! The reporter doesn’t
understand the details, there are two cables on this model. At 30mm I’m
guessing it’s the larger stationary/support cable. This is at ropeways.net. [The photo didn't paste. It shows 3 cars close together on a support rope plus a haul rope.]

 

Mont Blanc cable car break threatens summer season

https://www.connexionfrance.com/var/connexion/storage/images/media/images/mont-blanc/590373-1-eng-GB/mont-blanc_articleimage.jpgThe
Panoramic Mont-Blanc télécabine links “egg” cabins between the Aiguille du Midi
and the Pointe Helbronner mountain

The summer
season at Mont Blanc could be threatened after the main cable holding up the
mountain’s télécabines was cut during Storm Eleanor.

The
Panoramic Mont-Blanc télécabine service, which links “egg” cabins
between the Aiguille du Midi peak on the French side of the border and the
Pointe Helbronner mountain on the Italian side (as opposed to the larger télépherique),
is out of action after winds of up to 250kph at an altitude of 3,700m caused
the main cable line to break in two places, reports news source FranceInfo.

Storm
Eleanor ripped through parts of France on January 3.

The high
wind aggravated the situation, in which 70cm of frost and ice had reportedly
built up on 3.8km of the cable, which is 30mm in diameter. This is the first
time it has been broken in adverse weather.

“It’s a
first for me, to see a 30mm carrying cable cut in two,” said Mathieu
Dechavanne, CEO of the Compagnie du Mont-Blanc.

He
explained: “The storm winds probably caused the cable to oscillate, between the
pylons and the cable itself. It must have come out of its runner, before being
cut at both ends, and falling from the pylon it was hanging from."

Now, repair
work will begin to replace the cable, but the télécabine service is
not expected to re-open until at least mid-June, according to Dechavanne,
meaning that the summer season - which begins from late April to early May -
may suffer.

 

Comments

  • mapnutmapnut expert
    Posts: 896
    30 mm? That's only 1.2 inches!
  • joshua_segaljoshua_segal expert
    Posts: 2,136
    Sounds like the wind created a resonant vibration akin to the Tacoma Narrows Bridge.  Lucky no one was on it at the time.
  • TomWhiteTomWhite expert
    Posts: 581
    Oops, "cut in two", not in two places.
  • obienickobienick expert
    Posts: 1,102
    It might not have broken due to the wind, but rather the rime. 70 cm is 27.5 inches. That's a lot of ice on a lift.
  • TomWhiteTomWhite expert
    Posts: 581
    I wonder if 70cm is a misprint. If it is 70mm that's 2.75" of ice on a cable less than 1 1/2", which seems more likely. 
  • patrick_torsellpatrick_torsell intermediate
    Posts: 25
    mapnut said:

    30 mm? That's only 1.2 inches!

    From a quick look at a photo from the FranceInfo link, it looks like a dual cable ropeway, with a small-diameter haul rope, and a larger track rope on which the carriers actually ride. See https://www.francetvinfo.fr/image/75im3a3a8-e103/1200/450/14094795.jpg
  • TomWhiteTomWhite expert
    Posts: 581
    I realized another mistake. While 3 cabins close together is typical for a pulse, obviously this isn't since it has a track and haul rope. Now 30mm does seem small for a single track rope. It sounds like that's what broke. They are replacing the cable. If it was just the haul rope, that probably could be respliced. 
  • patrick_torsellpatrick_torsell intermediate
    edited January 11 Posts: 25
    TomWhite said:

    I realized another mistake. While 3 cabins close together is typical for a pulse, obviously this isn't since it has a track and haul rope. Now 30mm does seem small for a single track rope. It sounds like that's what broke. They are replacing the cable. If it was just the haul rope, that probably could be respliced. 

    I can't find enough pictures to confirm, but it honestly looks like a jig-back.

    I believe the haul rope is the smaller diameter of the two, as it simply provides motive force, while the track rope (probably a Z-lock rope) provides support to the carriers. Assuming that the haul rope is what broke, as I suspect--and correct me if I'm wrong--they would have to do a double splice with a new piece of rope to have enough length for tails. A clean break can't be spliced without huge movement (beyond mechanical limits) of the tension system. With that diameter, you'd need tails of about 25' IIRC. In-tact ropes can be shortened by re-splicing, but this is done at the original splice point. And in this case, given the extent of the damage, there's probably reason to suspect additional damage to the rope (NDT would confirm), hence the preference for replacement over repair. Though, admittedly, this isn't my area of expertise, so take it for what it's worth. Just trying to wrap my head around the scenario.
  • ceoceo intermediate
    Posts: 36
    This thing runs across the summit glacier of Mont Blanc, between the Aguille de Midi peak on the France side and Pointe Heilbronner on the Italy side. It's a bicable pulse gondola, I'm pretty sure, with one tower suspended on cables between two rocky outcrops, which you can see in the background of the article linked above. It also states that it was the track rope that broke, and that it will be replaced over the summer.

    And 70mm of rime won't break a cable, but 70cm sure will. Up there I have no problem believing that could happen. It astonishes me that they leave the cabins on the line over the winter (it only runs in the summer), but probably they have no place to put them.
  • TomWhiteTomWhite expert
    Posts: 581

    A few weeks ago Mike at Tenney had a video of them running
    the Hornet (slowly) during the ice storm. He showed slush dropping off the
    cable at the base terminal. I recall workers going up towers to break ice off
    pulleys on the gondi. Do any resorts have systems to scrap ice off haul ropes?

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