Cable car disaster in Italy 3

[LittleInch]

Not a huge amount of detail at the moment but a dreadful tragedy and difficult to understand how this could happen. The factor of safety on a cable car cable must be huge as it is so vital.

https://www.theguardian.com/world/2021/may/23/at-least-eight-dead-in-italian-cable-car-accident

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[Tomfh]

Other than self weight there doesn't look to be a whole heap holding the cable car to the wire though?

It's always a trade off between passing the towers and keeping the car attached to the wire.

If the car ran away freely after tow line failure it's difficult to imagine a good outcome, regardless of whether it was looped around the main line.

 

[itsmoked]

I agree Tom. I'd expect the cable to saw thru the safety loop quickly or for the gondola to hit bottom at slightly subsonic speeds with predictable results.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[davidbeach]

I'm just glad all worked well one fine day in June of 2018. I was on that car going down; don't have photos to show which car I was in going up, but definitely in the car on the south cable going down. Looking at the photos, it's actually three rides to the top. Starts with FacEngrPE's images from 24 May 21. Then part way up that one ends and you walk, no more than about 50m, to second of that type; the one that failed. That second one gets you nearly to the top and the last bit is on a ski lift type of system. That ski lift system also covers the course of an alpine slide, so it could get a lot more total riders than the two gondola lifts.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[Alistair_Heaton]

You have to remember that most of these cable car systems are decades old.

If you look at the modern ones they are completely different beasts.

In fact the old ones are very country dependant on the safety systems if they have any at all. And you really don't want to see the ones in the old Soviet nation's. The cable car in Barcelona looks decidedly dodgy as well.

 

[1503-44]

This one here on Tenerife is looking pretty skinny today. They had to rescue 70 people, 35/gondola in December. The cars stopped 400m from the top and 400m from the bottom.

(Dutch)

https://www.tenerifevakantie.com/teleferico-del-teide-defect/

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[Alistair_Heaton]

Wonder what's in that white box?

Maybe a drag anchor of some form

 

[LittleInch]

I was thinking the same thing - if you open the image in a new tab and zoom in it looks like two sets of grippers / brake pads for the cable - I can only presume this is the system that didn't work on one of the cars in Italy.

Now you start to wonder how often they test it....

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[dik]

test?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

At intermediate supports, are the cables supported from 'little chairs' from the bottom? to allow the 'wheel system' to travel over?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[LittleInch]

It's not easy to see but I think they get gripped by a number of thin half shell clamps which are only a little bigger diameter than the cable and feathered.

So the car does vibrate a bit as it goes over the cable mounts. Basically the reverse of what happens on a gondola system where the gondola / seat clamp goes over the moving rollers.

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[FacEngrPE]

Some news with more technical content. It seems inspections and regular maintenance occur. The technical information is a bit jumbled on translation, perhaps someone fluent in Italian can make sense of the article in it's original language.

Cable car crashed, the spectrum of Morandi: last revision in 2016. VIDEO

From the controls to the cable: the enigmas on the tragedy of Mottarone

https://www.italy24news.com/local/65055.html[/URL]]Meanwhile, the South Tyrolean company Leitner, responsible for the maintenance Stresa-Mottarone cableway plant, after yesterday’s tragedy, declares himself available to the judiciary, specifying that “the daily and weekly checks required by the operating regulations and the use and maintenance manual are the responsibility of the operator“. In a note, the company announces the list of checks and maintenance in recent months, “according to the requirements of current legislation, on the basis of the maintenance contract signed with the management company Ferrovie del Mottarone“.

On May 3, 2021, maintenance and control of vehicle hydraulic braking units; the non-destructive tests on all the mechanical safety components of the plant envisaged by the five-year review, expiring in August 2021, were brought forward from March 29 to April 1 2021; on 18 March 2021 operational tests of the entire drive system; on 4 and 5 March lubrication and checks of the rollers and pulleys of the stations; on 1 December 2020 ‘fake cuts’ (test which involves a simulation of the breaking of the hauling cable and consequent activation of the emergency brake); on November 5, 2020 periodic magnetic inductive check of the hauling ropes and all the ropes of the plant with positive results.

 

[dik]

Thanks...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[MartinLe]

I've seen this in german media:

https://www.sueddeutsche.de/panorama/seilbahn-lago-maggiore-festnahme-1.5304195

To paraphrase:
three arrested for manupilating the brake system
There where issues with the brake system that would have to be repaired with a lengthy procedure,
instead they deactivted the brake by installing a fork like thing ("Vorlegegabel" would be a serving fork), to avoid downtime and loss of income
Still unclear why the cable broke

 

[LittleInch]

That link by MartinLe is pretty damning.

I didn't know it had nearly reached the top before the pull cable snapped, but, from the reports, jamming open the brake pads so that the cable car would work is most definitely criminal behavior.

Being in something out of control and hurtling down the mountain must have been truly terrifying. Really doesn't bear thinking about.

Similar report here.

https://clippers.com.pl/gondola-accident-in-italy-suspects-testify-due-to-possible-tampering/

Key phrase - they made the decision on the basis that "the cable will never break".

There be a lesson to us all on low probability high consequence events. Nothing is perfect and failures do happen. This system had been there 50 years so possibly approaching a million operations. Then the one in a million event happens. And you've disabled your safety system.

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[1503-44]

There is that fallacy in the low probability - high consequence events mathametics. Right now nobody can say for sure if its a 1 in a MM or 1 in 50yr event. There is so little data on low probability events, all we can do many times is to make a WAG that the sum of all the probabilities involved will be inconsequential. Then there are those times that we do the math right, but somebody forgot there is a >0 probability of defeating some protection system that is many orders of magnitude higher than the sum of all the other numbers on the spreadsheet. The probability of defeating the safety system now looks like it is 1:50yrs, but someone will also come along and take that one occurrence as over the total time of all cable car oprations in the whole world and find, no it really is 1:100 MM. Here its 1:50, but everywhere its 1:100 MM. Its the one I'm riding that's worrying. Would you not have to ride every cable car in the world for the statistics to directly apply to you?

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[MartinLe]

Now I'm speculating but: The problem with the brake turns up shortly after the cable car was closed due to Covid. Did they do the normal maintenance on the braking sytem during that time?
Is there a specific maintenance schedule forthe calbes? Quality check, lubrication - and was that followed?

My thinking with redundancies is - what could be a common cause for two, in themselves unlikely, failures. The one thing I come up with is maintenance.

Other possibility: Did the cable break near the faulty car? Could the repair attempts or the problem have damaged the cable?

According to the link I posted there's a legal fight over ownership of the cable car - communal or regional? Noone wants it. Did this legal bullshit (onoing since 1997) in any way affect maintenance and operation?

 

[LittleInch]

From the reports it looks like they discovered the fault which sounds like it was clamping on when it shouldn't as they were dusting the cars off and doing some trial runs after the long covid hiatus.

https://www.theguardian.com/world/2021/may/26/italian-cable-car-brakes-tampered-with-say-prosecutors

This is equally bad as if the car stops whilst you're dangling in mid air you need helicopters and people need to climb onto the roof to escape etc etc. Not as bad as failing to work when its needed but you can see how the pressure of needing to get the cars working so that they can get revenue after xx months of no operation can cloud the mind.

I wasn't trying to say with the statistics that if this was a one in a million event then it happens after the millionth time, but give some context to those numbers.

Failure rates on equipment I design is in this order of magnitude but incidents still happen.

And that's the point I'm trying to make. just because something is a very low probability doesn't mean it can't happen and you rarely get any idea of when it could happen. So maintain all the safety devices you have and don't rely on the "it won't break / fail / leak / explode" thoughts to justify operating without them.

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[thebard3]

Most companies that I have been dealing with used Covid shutdown time to perform maintenance and upgrades. Airlines have many passenger jets that have been sitting around unused for months. I'd expect a robust checkout on all systems before they're returned to service. Disabling a safety system is never an acceptable practice.

Brad Waybright

The more you know, the more you know you don't know.

 

[IRstuff]

If the cable could never break, there wouldn't have been a need to design a braking system. These guys are screwed; their only saving grace is that the EU doesn't have a death penalty.

TTFN (ta ta for now)
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[MartinLe]

"Leitner di Vipiteno said on Monday that a series of checks had been carried out over the past seven months, starting with the yearly magnetic inspections on the primary cables of the lift in November 2020 and followed by further checks on safety components and braking systems between late March and early May."

You never cease to learn. This is the first I've heard of magnetic steel cable inspections:

https://www.ndt.net/article/v04n08/zawada/zawada.htm

I still want to know how exactly they jammend the brakes open.