Blackcomb Gondola accident - Page 4

The probable reasoning for not having drain holes is that they're supposed to be a sealed system - no water in, no water out. The failures I was talking about aren't so much the weld failure once ice got in there as the failure that initially let water in. Again, this is a risk that could have been mitigated through variuos methods mentioned here, but they all have their downsides.

My guess is the reasoning behind no "drainage holes" is to prevent moisture and chemicals from entering the pipe at all, which could cause difficult to see (and nearly impossible to repair) corrosion on the internal faces of the post.
I'll be very interested to see how water got in in the first place, if they ever release that information.

What happens when the drain holes freeze?

In other engineering disasters this week:
Atlanta Bridge Collapse at Botanical Garden; One Dead

http://www.myfoxspokane.com/myfox/pa...Y&pageId=3.3.1

Correctly designed drain holes shouldn't freeze completely over. They may not move all the water out, but they will move enough water to prevent the whole tower base from filling up.

Any rain making it's way into the tower is not going to be entering the tower at such high flow rates that the drains will be overwhelmed..

Design it so it breaks safely?

Not sure what you mean here...

Notice how the cables didn't snap?
Notice how the gondolas didn't fall off?
Notice how the remaining gondolas hardly moved?
Or how the towers above and below didn't fail?
Or how, despite a single cable appearing to support the weight of half a tower, it didn't even come off the pulleys?

This was a catastrophic failure. And it failed 'safe'.

Excellent job by the engineers if you ask me. (Not so sure about maintenance/monitoring - that would be even more speculative than just looking at the pics.)

Clearly they need to address ice jacking but I agree that some kind of foam filling would be a superb idea to prevent catastrophic failure - not by keeping water out but by absorbing a lot of water->ice expansion potential.

Personally I think drain holes sounds like a naff solution prone to blockages of all sorts.

However, if they are designed to be dry, known to occasionally leak and are prone to catastrophic failure from an 'extreme' leak then the dryness should be monitored.

Thank the designers that no-one was killed.

Plenty of "sealed" systems have drain holes even when it seems odd (ski goggle lenses, boats, airplane wings, etc). In reality, if an object is not a pressure vessel, I think facilitating some sort of ventilation/drainage makes sense. As soon as you try to make something airtight or watertight and then "rely" on that for design function and safety, it opens up a world of possible failure scenarios. Many of them oddball and unexpected. This is a perfect example. I'd rather not rely on air/water-tight properties for a load bearing structure if I can help it.

This is a perfect example where the design philosophy failed. No drains were present because the design was based on the notion that the tower was watertight and no water could get in. When that assumption failed, the lack of drains became a major flaw.

On thing's for sure, this definitely makes open truss-type towers look a little more appealing.

As for the failure in this case, I think it was dumb luck that this was a rather benign failure and nobody got seriously hurt or killed. It could easily have been a lot worse. I'd be surprised if this sort of failure scenario is accounted for in any of their design rules.

The way I see it (and its usually cross-eyed), the concrete filled lower tower section had a considerable thermal mass which created a thermal gradient at the tower connection where the unfilled top tower pipe and solid plate flange would be much cooler than the lower section under the right conditions. This would have created a condensing surface (the bottom of the steel plate) for moisture as the upper section cooled relative to the lower concrete filled section. The concrete appeared to be closely capped by the steel plates so, we aren't talking about a tube filled with water, but a fraction of an inch of liquid water forming on the steel plate that was prone to freezing as the upper tube section cooled. Expansion against the non-compressible concrete immediately below would do the rest to lift the steel plate and break the whole connection. All that was needed was a compressible material or air gap below the steel plate. A drain plug may not be the answer.

This is purely speculative, in keeping with most of this thread.

From a discussion yesterday with someone who had some background in lift testing (not entirely clear on what it was, but more than just a casual observer), condensation can be the more likely source of water than actual water leaking in.

An article I read today suggested that the reason Doppelmayr doesn't install drainage holes is to prevent corrosion on the inside of the towers, but that most other manufacturers do have drainage holes by spec, so it seems like something in need of rethinking on Doppelmayr's part.

I think its more likely to be a standard that prohibits the use of concrete to within a minimum distance of a solid flange. It occurs to me that if that bottom tower section was filled with concrete, the flange was welded after the tower was set and filled. Who knows if Doppelmayr ever even contemplated their tower supports would be filled with concrete.

Yep, user-proofing is hard.

There hasn't been any mention (unless I missed it) of the fact that tower 4 is on the edge of Fitzsimmons Creek, which is fast moving water that always kicks up a lot of moisture. It wouldn't surprise me if the humidity level standing at that tower were to be above 80% every minute of every day. Having said that, wouldn't that result in condensation forming on the inside of the tower, then below freezing air temps would result in the ice-jacking?

Corrosion? Guess they never heard of paint or zinc plating. There are ships that have sunk and now sit at the bottom of the ocean for decades and still have much of the paint that was originally applied, so there is a solution and it isn't rocket science.

So, is the upper portion running?

The snap was on the lower portion of the lift, in the short section before the "midstation". The portion above this is independant (I didn't know that until reading the linked-to story). Does anyone know if the upper portion is running?

If it is, it might be a opportune time to rent a condo in the upper area, where you can walk to the midstation... everyone else will have to get onto the hill via the P2P, so my guess is that Black will be pretty devoid of people.

Of course, there's the snow issue too...

Maury

Sounds like the upper portion reopened today.

http://www.whistlerblackcomb.com/med...-09/081219.htm

Don't think Blackcomb will be devoid of people - Wizard can move up a bunch of people.

I'll be on first chair at the Wizard tomorrow morning... then zip across the P2P for a few runs on Whistler, then ski out (downloading no longer necessary) to the village and work at 2...
Any other Bears gonna be there??

Condensation would only result in an accumulation of water if (a) there is an opening for moisture-laden air to enter, and (b) if there is no drain for accumulating water to drain out.

The though that comes to mind is a void in a weld or other unintended entrance for moisture. It may have taken years for that much water to accumulate.

Coatings are excellent if the right ones are applied, but you do not want to depend on anything that cannot be inspected and repaired.

Could be, but the concrete itself is porous to air and moisture, and the column would act as a chimney to convey moisture laden air if there was any void up high.

As I said before, it speculative, but may merit consideration as part of a root cause analysis.

It sems odd that moisture would collect inside a lift tower halfway up the tower or that anyone would construct a hollow steel tower with such a water trap without providing a few weep holes. Moisture could collect inside from condensation alone if there were no exit fot the moisture but halfway up the tower? Thats a huge amount of water. I would supect a faulty weld and or understrength materials. I understand counterfit components like fake high strength bolts is a real problem for the airline industry, for example. A steel pipe like that should be much much stronger that any loads it would normally be subjected to. I didn't notice any evidence of deformation in the photograph which you might expect to see if column buckling had occurred.

The failure was at the weld that bonded the connecting flange to the lower tower section. The tower "tube" was filled with concrete, so when moisture froze at the flange interface, it lifted off the concrete, breaking the weld.

That didn't take long:

EXCALIBUR GONDOLA WILL FULLY RE-OPEN DECEMBER 24

BC Safety Authority and Doppelmayr testing protocol complete

WHISTLER BC, December 23, 2008 - The BC Safety Authority has reinstated
the operating permit for the lower line of Blackcomb Mountain's
Excalibur Gondola following inspections Tuesday. Repair work on tower 4
was completed Monday and testing took place throughout Tuesday in
accordance with BC Safety Authority and Doppelmayr test protocol. The
Excalibur Gondola will be in full operation December 24.

"We are extremely pleased with the efficiency in which we have been able
to return this lift to operation," says Wayne Wiltse, Whistler
Blackcomb's lift maintenance manager. "The tower has been rebuilt, and the
cable has been inspected. They have both been non-destructively tested to
ensure they meet all code requirements. A thorough inspection, as outlined
in Whistler Blackcomb's Safety Management Plan, and
following procedures recommended by the lift manufacturer, has been
undertaken to ensure the safety of our guests. In addition, the BC Safety
Authority has been on-site Tuesday doing its own inspection before
reinstating our operating certificate."

In accordance with the lift manufacturer's test protocol, Whistler
Blackcomb lift maintenance crews perform a "sounding" test on the towers
to check for the presence of water. This test was considered an
effective way to check for the presence of water in towers. Following the
failure of tower 4, all Doppelmayr lift towers across Whistler Blackcomb
were checked for water build-up. This was done first by
Whistler Blackcomb lift maintenance crews on Tuesday night after the
incident. A secondary inspection was undertaken by Whistler Blackcomb in
conjunction with the BC Safety Authority the next morning before
operations commenced for the day. Since then, BC Safety Authority has
issued a Safety Order requiring all BC ski resorts to inspect all lift
towers for water, regardless of manufacturer. In light of the Excalibur
incident, Doppelmayr has revised its test protocol to now include
concrete filled towers.

The investigation into last week's tower failure remains ongoing. The
cause of the tower failure was confirmed by early the next morning,
December 17, and was due to an unusual situation called "ice-jacking."
Water had accumulated within the tower, then transformed to ice to a point
whereby the pressure from the ice created a rupture that separated the two
sections of the tower. The force of the ice expansion and the subsequent
rupture has been estimated at 800 tonnes of pressure. Prior testing had
not revealed this ice build-up due to the tower being
concrete-filled.

"Our commitment to safety at Whistler Blackcomb is uncompromised," says
Doug Forseth, Whistler Blackcomb's senior vice president of operations.
"We have been working around the clock with the authorities and
independent experts to understand what happened here last week. Through
these efforts, a new Safety Order from the BC Safety Authority, and a
safety bulletin from the lift manufacturer has been distributed to ski
resort operators in BC and to the industry, in the wake of this
incident."

Updated information about Tuesday's incident on the lower line of the
Excalibur Gondola will continue to be available for guests and media from
the homepage at www.whistlerblackcomb.com
<http://www.whistlerblackcomb.com/> . The web site also includes further
information about Whistler Blackcomb's operating plan, open lifts, snow
conditions, grooming and open terrain.

-30-

Maybe the same genius figured out what would happen when the drainage holes filled up with ice and snow?? SRSLY??

Actually holes can be configured in such a way such that the icing even if some were present would never be a factor. Additionally, an extremely simple generator could be added to the tower such that the cable spinning it would generate just enough power to operate a heating element wire running from top to bottom of the inside of the tower.....free antifreeze device, green and problem solved.....like I said its not rocket science.

How would any holes, regardless of configuration, help if they were coated with ice, or the tower was filled with snow/ice (that the holes allowed in)?
Heating the holes would seem to be a solution, but I'm not aware that this is ever done.

Anyway, for icing at the flange (as seems to be the case here) I doubt anything like this would've worked.

I there were weep holes located throughout the pole any day that temps were above freezing water would drain out...there simply would never be an opportunity for ice to accumulate.

A heating element and or a good gasket would prevent icing at the flange.

Not. At lest the free and green part. The energy that would be used for this device would come from the lift which would add to its load which means that the motor that runs the thing would need more energy to move the lift. Even if the power for this lift comes from hydro (which it almost certainly does) it still isn't completely green given the problems with dams and fish, etc.

So they'll have to pay more for the non-green power, albeit not much. It's not free, nor is it green.

Again, the heating makes sense, but think about a typical weather scenario--rain, fog, and then snow/ice, followed by a long period of very cold temperature and then humidity at near freezing temperatures. The ice coating the structure would never melt, and snow/ice could easily build up.

Given the large amount of energy required to run the lift, I think the heating element would be virtually free--as in less than .1% of additional load on the lift motor. Probably those tiny weather vane type windmills could power it, too, if placed on top of each tower. A car with running lights on probably has to expend a greater percentage of its energy for the lights than a ski lift would have to for this.

How long had this thing been up? How many others are there in the world that have similar construction? Either this was a fluke occurrence or they'd be falling like dominoes all over the place wouldn't they? From my armchair engineer's seat (no advanced degrees in mechanical engineering here) I'm guessing the concrete absorbed moisture to the point that when it froze it expanded and popped the weld. Assuming that is a freak occurrence and based on the fact that they didn't tear down the other towers and rebuild them differently It is probably safe to say that there wasn't anything inherently wrong with it, just a fluke of fluke things.

P. S. how bout solar powered battery heaters heaters would help?

I think this gondi's been up for six or seven years? Don't remember exactly, but it's been awhile and there seem to be plenty of other Doppelmayr gondolas around.

Pretty sure those would be useless in coastal BC for about half of each winter.

They'd work great in the summer.