Whistler Blackcomb Gondola collapse

A snowHead

The Globe and Mail is reporting 'ice-jacking' as the cause of the lift tower's rupture:

http://www.theglobeandmail.com/servlet/story/RTGAM.20081217.wgondola1217/BNStory/National/?page=rss&id=RTGAM.20081217.wgondola1217

A snowHead

Now that really should not have occured, usually the joint should be either welded solid (so no water an penetrate) or if it's bolted then it should be beded down on some form of sealant, damage due to freeze/thaw action is well known and I'd be very surprised if Dopplemeyer had not allowed for this, the only other alternative is that poor maintenance had resulted in a larger than normal gap fror water to get in

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The UK press are now addressing the story. The Times (by Sean Newsom, who's just returned from the launch of the Peak 2 Peak gondola in Whistler):

Whistler will have to convince the world its lifts are safe

The Daily Mail has good photos:

Cable car crash leaves more than 50 passengers dangling in mid-air

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It's on the BBC 6pm news (at 18:26....)

streaming water underneath some of the gondola's thank goodness they didn't drop into that Shocked

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Yesss I remember admiring that freezing river from said bubbles earlier this year! One of those rare things seeing something like that, knowing I was on there in January

Good that it wasn't a complete disaster though.

"official" reports from Intrawest on their website http://www.whistlerblackcomb.com/excalibur/index.htm

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Other thing to mention - the tower that collapsed was part of the lower section of the gondola, between the Whistler base and mid station. From memory its fairly short and the terrain on the whole, not tooo steep. The upper section is on a seperate cable.
God forbid one of the steep sections on the upper part have failed - that really could have been very nasty indeed.

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Presumably the disaster will also be subject to a public engineers' enquiry, independent of Intrawest.

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In the German skiing forum, there is a report (in German), http://www.alpinforum.com/forum/viewtopic.php?f=35&t=29344 from LiftFreak (who is in Whistler), which explains that the tower filled up somehow with water and then suffered the "burst pipe syndrome" when the water froze, ripping it apart with out breaking at the flange. There is also a photo which seems to show the lower part of the tower filled with ice.

Ooops, see now that this was already mentioned above - hadn't seen the second page Embarassed

Seemingly Graham Bell was in one of the lifts that plunketed to the ground. Fortunately he got out unhurt. Would be quite cool if he had a cameraman in there with him . Could add some interest to SkiSunday.

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espri, Looking at the pictures I think that the reports are slightly incorrect, what you have with the towers are a pair of sealed tubes with a plate on the top of the lower tube and the bottom of the upper which have a series of bolt holes going arround them, it would appear that water managed to penetrate between these two plates and when it froze it exerted sufficient pressure to either break the bolts or pull them through the bolt holes (pictures don't have enough detail or correct angles to work out which) now as an engineer I would expect ther to have been some sort of seal between the two plates to prevent this from occuring, so either the design was bad and no seal was provided (but why did this not happen in the previous 14 years) or the seal failed recently or during regular maintenance someone failed to replace the seal, I've done a fair bit of structual steel design work in recent years and even in the uk you design teh joints so as to prevent water ingress for just this reason, where you cannot prevent ingress you design drains into the system, but from preference you seal joints against the water

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D G Orf You may well be right, though SkiFreak, the chap who is there reports:
"Irgendwie hat sich die stütze mit wasser gefüllt (wie genau ist noch unklar), dieses ist gefrohren (haben seit letztem freitag so im durchschitt -12 grad im tal und -25 am berg) und hat den Flansch der am oberen teil des unteren stützenteils angeschweißt ist bei der schweißnaht abgerissen. Sprich es haben nicht die bolzen am flansch selber nachgegeben, der flansch ist immer noch zusammen, jedoch beide teile jetzt am unteren ende des oberen Stützenteils und nichts mehr am oberen teil des unteren stützenteils."

My translation:
"The tower had filled with water somehow (just how is still unclear), this had frozen (we've had around -12°C in the valley and -25°C up the hill since last Friday) and that had torn off the flange at the weld where it is welded at the top of the lower section of the tower. That's to say, it wasn't the bolts on the flange itself that failed: the flange is still bolted together but both parts (of the flange) are now on the lower end of the upper section of the tower and there's nothing at the upper end of the lower section."

I'm assuming he has seen pretty closely what happened. Of course, it may all just be an assumption on his part. The question is certainly justified, why it hadn't happened before (or elsewhere in the world). But I suppose there could be some explanation why the seal failed in this particular case.

"Edit" Looking at the report in the 'globeandmail' link above, it does seem more to suggest that the flange failed. However, in the German forum there's a link to pictures at Spiegel Online,
http://www.spiegel.de/fotostrecke/fotostrecke-38115.html#backToArticle=596915, which do seem to show that there is no flange left on the lower section of the tower.

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Hi Snowheads,
This one hits close to home for me, as my lovely girlfriend Rebecca was one of the 53 people stranded. I'm currently in Serbia on business, but my coworkers had heard that she was MIA, and low and behold she answered my mobile call. At that time she had been waiting an hour- she was alone in her cabin, above the base 2 parking lot, and my call was very much welcomed. She had seen the gondolas bouncing wildly behind her-her cabin only swayed moderately, and so she was under the impression that a cabin had fallen off. (which was later revealed as incorrect). She kept in good spirits, they eventually evacuated her using a hydraulic "cherry picker", after 2.5 hours. By that time she was uncomfortably cold, as she wasn't dressed in ski gear- she had simply been using the gondola to commute to work.

Also- kudos to all emergency response crews- it was a joint effort that was coordinated very smoothly. My roommate Norm is the firefighter with the red hat, seen evacuating the 6 passengers from the gondola over fitz creek. There's been some talk about the fire dept replacing that very large fire truck "ladder"- but I hope this event causes them to reconsider, as it was the only machine in the valley capable of reaching that gondola.

Doppelmayr is an excellent ropeway manufacturer- in this case it was a tower failure-I do not know which company was subcontracted on the tower installation in 1994. The lower portion of the tower is filled with concrete- this is not normal practice, but was done due to the fact that a roadway is adjacent to the tower location, so the tower was filled with concrete to have more mass & to be able to survive a horizontal impact from a vehicle. All that means is that it would have taken much less water volume for the ice to reach the underside of the connection flange.

All in all, the systems worked correctly in failure mode- having the grips of all cabins stay on the line under large loading conditions validates the grips design.

Anyway, glad to hear that everything went smoothly. I rode one of the first P2P cabins last week, and plan on riding them, and any other lift on the mountain , as soon as I'm back home.

Anybody want to hazard a guess at how many resorts are checking their towers very very carefully this morning? For me the real likely impact of this may be on other lifts elsewhere.

You know it makes sense.

stoatsbrother, and reviewing their maintenance and inspection policies, including training and supervision - I hope.

Otherwise you'll just go on seeing the one name:

From comments:

A snowHead

Lifts are as safe as commercial flying if you consider the the numbers of passengers. poo-poo happens now & again.

Two of the biggest accidents that made the news that i can remember were not even lift faults just freak third party accidents. i.e

Italian Cable car hit by US Airforce Jet
Solden Gondola hit by flying concrete from a Helicopter.

I doubt the lift can operate again this season, the investigation & conclusions will have to be done before any repair or rebuild

Anyway, its not good for the Olympic image.

Rendlbahn (Gondola) in St Anton opens tomorrow & thats not without preious incidents !

A snowHead

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stanton,

David can speak for hiimself and normally does but I think he was just pointing out the fact that you didn't type "poo poo happens" but "s h i t happens". Goldsmith is the Frank Spencer of the ski world. From what I understand he has been involved with many ski accident investigations in the past although I think others actually chased the ambulance.

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Having been involved in airworthiness, I do wonder if, as stanton says so authoritatively, that the safety of major ski lift apparatus, though high (and acceptable to me) is as good per passenger trip as a passenger aircraft subject to the aviation authority of a major Western nation . For a relatively small number of lifts there does seem to be a surprisingly high number of accidents. Moreover, this thread suggested that the quality control of materials might not be tight.

Oh by the way:

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CTVBC has pretty extensive coverage of the incident, including several videos, http://www.ctvbc.ctv.ca/servlet/an/local/CTVNews/20081217/gondola_follow_081217?hub=BritishColumbiaHome.

The accident is being put down to "ice jacking", i.e. expanding ice in the lower section of the tower breaking off the upper section near the join. Doppelmayr is said to be issuing a related warning to lift operators.

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espri, hmm.

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Couldn't agree more. But there is inevitably a commercial imperative to nip a PR disaster in the bud and blame a natural factor (ice) as the primary cause.

I think DGO's initial instincts as an engineer on p.1 were correct, and the questions that must be addressed are obvious: to look at the metal, the welding and the jointing.

The column was full of water?

This is the latest report from a Canadian media [CBC in this case] that doesn't appear to be asking many questions:

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Canada has a competent safety organisation, the Transportation Safety Board of Canada, http://www.tsb.gc.ca/, so I'm sure that this potentially catastrophic accident will be fully investigated. Looking at their web site, I don't see any indication that the TSB handles cases related to cable cars but I assume that there is some appropriate authority to look at this case.

More developments. It appeared (I thought) from the earlier reports that Whistler and Doppelmayr had reached the "ice-jacking" conclusion. This report from the Globe and Mail suggests that it is endorsed by the public authority:

You know it makes sense.

This additional detail from news1130.com

Otherwise you'll just go on seeing the one name:

http://www.ltci.co.uk/LTC_Technical_Bulletins/DOPPELMAYR_SKY_RIDE.pdf - page 38-40 provides the details of the water intrusion problem, the recommended inspection regime to detect it, and details of the use of drain holes to correct the problem.

The list of safety bulletins might look long, but to me it is reassuring that they seem to be on top of safety - anyone who has worked on specialist vehicles or aircraft will be familiar with this sort of stuff, but in far greater volume.

A snowHead

Intrestingly the document makes the same comment that I made earlier in this thread, that the bases should be sealed with mastic or similar material to prevent water ingress, my guess and it's only that is that at some point perhaps during the last year the towers were serviced and someone forgot to put the mastic into the joint, the other alternative might be that after 14 years whatever material they used to seal the joint had decayed and no one noticed, I suspect an awful lot of lift companies will be double checking their towers in the coming week

A snowHead

I guess the other question which will be exercising a few minds is whether the concrete fill poured into 4 towers, including the one which failed, added to the problem by raising the base of the water table up to the flange, rather than starting it at ground level. No doubt the maintenance records will also be under some scrutiny, and the recommended check interval of 1 year might be modified as a result of this failure, since checking for water levels during June might not detect a problem which only occurs between late autumn and late spring.

The engineer in me wonders what the cost would be to put a stress gauge on each tower...

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David Goldsmith, & D G Orf,

Interesting thread- Hopefully my explantions below shed some more light on the matter.

The lower column of tower 4 was (is) full of concrete, most certainly a small amount of airspace was left between the top of the concrete, and the underside of the top flange of the lower section of the tower.
Both flanges and their bolts remained intact, i've heard no reports of fatigue or corrosion. The ice pressure appears to have broken the weld between the bottom section of the tower and it's flange, from the photos my colleague reviewed online it appears as though the weld remained on the column, and separated from the flange.

So the real question is how did the water get into the tower? I think the answer will be found after they establish how the concrete poured into the lower section. The lower tower top-flange is typically solid -it's not just a ring of steel, welded to the end of the tower. As discussed above, Doppelmayr constructs "air tight" towers - the top of the tower is sealed by the solid flange. The top of the upper section of tower is also sealed- the cross bar is bolted onto a flange as well, but all holes are on the outside of the tower assembly.
In the case of this tower, the installers likely cut a hole in the center of the top flange of the lower tower section onsite, large enough to pour concrete in, once the lower section of the tower was upright. This hole must have allowed water into the lower section of the tower via a non-water tight seal- perhaps it took 14 years for enough water to fill up the bottom section of the tower. (probably only a few litres of water or even less due to the fact that the concrete had filled the void, as surmissed by Ousekjarr)

W/B has excellent maintenance procedures- I suspect that what will be found is that the typical & recommended method of testing for water / ice just isn't adequate for towers that have been filled with concrete. This is because typical maintenance checks use a "sounding method", where the worker's hit the towers to hear if water or ice is present inside. Because the tower was 99% (assumed) full of concrete- hitting it with a mallet wouldn't tell the maintenance people much. They probably would have only struck the upper section by climbing up the inspection ladders until they were above the join. So, the small airgap which filled with water and then broke the flange weld would have been almost impossible to detect using the recommended procedure.

Also from the photos- The ice is visible at the top of the tower, so it's not a case of water seeping in at the bottom via a poor mastic bond, wherein the ice jacking lifted the concrete inside the tower, breaking the flange. I strongly suspect that the water seaped in via the outer rim of the flange connection, and then into the lower section of tower via a hole in the flange which would have been required to fill the tower with concrete.

My bet is that the solution will be to drill inspection holes into all towers which have been filled with concreate- one at the bottom, and one just below the upper flange.

As an aside- towers on the infamous Yan lifts were constructed with steel pipes originally fabricated for use in transporting liquid - they had spiral welds, and Yan didn't use flanges / bolts to attach the towers to the concrete foundations. They would just dig a hole, prop up the tower, which had been site fabricated, and fill up the hole with concrete. Just like putting in fence posts in the back yard......

Btw- I work in the industry, and often work with Warren Sparks, who's a very experienced guy- an engineer by trade. And yes, there is an independant body, the transportation board (transport Canada), which is jointly investigating this incident. Finally, an industry source tells me that Doppelmayr Kelowna (where the towers are manufactured for Western Canada), is fabricating a new tower as we type, and will attempt to have the lower section of the gondola working before Dec 27th. That'll be quite a feat if they can pull it off.

Best regards

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Since no one seems to have updated this, I will let you know that it was caused by water inside the tower, which froze, expanded, and burst the weld and bolted flange. How the water got inside the tower is unknown at this stage. The term used to describe this is 'ice-jacking' and it has happened before in Idaho, USA. After that Dopplemayer changed the 'maintenance' procedure for the towers, which Whistler Blackcomb have adhered too. Unfortunately, the new process didn't work for towers which have concrete inside them, which this tower did. Not sure why it had concrete inside, as normally that is done in towers which are in avalanche zones, which this tower is nowhere near.
An independent QA company, which inspects the chairlifts every year, has been over both mountains, and have given the all-clear. The Blackcomb gondola 'Excalibur' is shut down for a while.
Terrible incident, and luckily no one got hurt. I am led to believe, Lift Maintenance were on the scene when it happened, they had noticed it was slightly out of alignment and were trying to work out why. So they had slowed the lift down to minimal speed, which may be a factor into why no serious damage was done, or lives lost.

edit: it seems there were multiple threads, and I was reading a 'dead' one. it had no posts since the 17th

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wbsr, The topic crossed over to page 2 on the 17th, unusual for newsforum topics Wink

Interesting the mention of lift crew being on site. Sounds like they actually are quite well on top of keeping the thing secure.

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I remember the YAN lifts - always seemed to be breaking down. Didn't people used to say it stood for "You're Airborne Now" ?

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espri, if you were to see where the tower is, It is would be very hard to hit it with a vehicle, even if you tried.

achilles, all lifts have 'mis-alignment' sensors on all towers. When they get triggered, it is normal procedure to slow the lift down. It wasn't 'constantly' out of alignment, so why stop it? We are talking about a haul rope mis-alignment, not the whole tower. Cables 'walk' constantly, and are allowed a certain tolerance. In this case it had hit its tolerance, just , a couple of times over a long period of time.

If the cable was to get too-misaligned, then it stops automatically, no problem, if your aircraft was to 'malfunction' it would crash wouldn't it, big difference.

Since it was at the end of the day, I'm sure they decided to just 'run it slow and download everyone' and then try to figure out the problem overnight.

If they were to stop and evacuate a lift, every time it has a mis-alignment or anti-collision fault, you would be never get to upload.

Anyway, that is not confirmed, but I personally know the person who was supposed to have been on the tower 5 minutes before it fell, next time I see them, I will ask for the details.

Help!!

Whistler Blackcomb Gondola collapse

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