Spectacularly dumb idea to hang that much weight (6 Tons!?) from the top of those walls. Those walls are clearly meant for vertical loads. And a much better option (if you feel you have to do this) was available so I really don't understand what made them choose this particular setup. Anybody with an ounce of structural engineering knowledge would have looped the cables through the drainage ports.
Right now this looks like a Darwin award candidate. They're very lucky that those walls contained enough rebar vertically to withstand this load, it's at the worst possible attachment point and at the worst possible angle (especially for the inner wall).
Edit: looking more closely at the picture it seems as though the cables under tension are actually running through the drainage ports of the back wall, the ropes at the top seem slack or loaded both top and bottom of the opposite so there is in fact mostly compressive load on the front wall and about 50% of sideways load on the opposing wall. Still, that structure was definitely not meant to be loaded like this.
This image best shows how they did it - http://jaccuzzi.ch/photos/700/1758_264_seb_11_.jpg - they looped the ropes over the top of the sides on both sides, suspending the platform directly under the bridge so there shouldn't have been any sideways force.
Still seems a bit stupid to put that much additional load on a 70 year old pedestrian bridge though.
This bridge was most likely not constructed as a pedestrian bridge. What you see in the back probably is the bridge that replaced this one when a one way bridge did not provide enough capacity anymore and the old bridge was re-purposed as a passenger and probably cyclist bridge.
Based on that it was definitely built for higher load than just a few pedestrians.
Edit: The German language Wikipedia article actually confirms this [1]. It states that the bridge was built for a traffic load of 13 tons and that the new bridge was built in 1993 to increase capacity. The old bridge was thoroughly renovated after the new bridge had been constructed. The bridge actually is well documented and is under protection as an architectural landmark. It was exhibited in the MoMA for a long time.
Based on the amount of prep these guys put into this and the available documentation I don't see why they should not have checked if what they wanted to do is possible.
That's weird. It definitely looks like it is the same bridge but that page says it has been removed.
The construction clearly shows a concrete bridge in the making (lots of concrete forms visible) whereas the heading of the page is 'Swiss timber bridges'.
as far as i understand it the timber bridge was the temporary bridge used to support the construction and then torn down after the concrete bridge was completed.
> ...platform directly under the bridge so there shouldn't have been any sideways force.
No net sideways force. Any +X force on the left wall will have a -X force on the right wall. If there's a tension T in the ropes across the top they'll be pulling the walls inward with a force of T causing a torque of T*height.
> If there's a tension T in the ropes across the top they'll be pulling the walls inward with a force of T causing a torque of T*height.
Almost, you'd still have to subtract the friction component across the 90 degree angle where the cable hangs down from the edge near the porthole but that's probably relatively small compared to the total (depends on cable material and any kind of padding they put in between the cable and the concrete).
It would have been a lot better to sling those cables through the portholes on both sides and to make it loop the bridge, one person would have to rappel down to get that started but you'd have zero load on the walls.
The longer I think about this the more I think those guys and girls were extremely lucky and I hope that this will not inspire any copycats to try this with other bridges or even the same one. It's a long way down.
I prefer to live in a frictionless world :) It looks like it was rope on metal (http://jaccuzzi.ch/photos/700/1722_264_03.jpg) with a coef. of friction of 0.2. My gut says the friction force will be at most half horizontal. That puts friction an order of magnitude lower than T, though that is more than I expected. (edit: damn, it rounds the corner from vertical to past horizontal so my symmetry argument doesn't quite hold.)
Why they went over the top of the walls I don't know, I think they wanted to measure the ropes exactly instead of adjusting it the day of. Like, that was where they drew the line of "unacceptable risk"? I agree a loop through the drain holes would have made their lives easier in a bunch of ways, except the tripping hazard would have made it a very risky project...
The bridge is 168.36m long and (I guess) about 2m wide. If there was 1" deep water all the way along that'd be about 10 tons of loading. But that'd be distributed along the entire length of the bridge, not concentrated at a point in the middle...
To be fair those walls were designed to take horizontal wind loads, too. 100mph wind translates to 0.17psi[0] which is ~220 lbs/square yard (of course you assume the force happens halfway up, not at the top of the wall!) If the ropes were spread out over 5 yards then that span should hold ~1500lbs against the face of the wall.
If that thing weighed 6 tons they may have made it out of the "designed to handle" range and into the "safety factor" range of inward forces on those walls. Surely those drainage ports weren't designed to handle upward loads?
I really can't believe some of them took their harnesses off while in the pool.
No, but they are designed to take a lateral load from a vehicle impacting them. In the US currently that load is about 4.5 tons at any one point. In a bridge like this where the parapet walls are an integral part of the structure, that would likely not be the limiting case and the walls would be even stronger than that.
Some more evidence that they had considered these things would have been nice, but civil structures are quite a bit stronger than people here seem to be giving them credit for. For example, the vertical design load from people walking on a bridge like this is something like 100 lb/ft^2. Meaning the bridge is designed to hold one jacuzzi every 10 or 15 feet, depending on how wide it is.
It seems like it would have been a better idea to bring the cables/ropes in through the hole at the bottom of the wall, rather than over the top. The lateral compressive load would then have been taken up by the bridge itself, rather than the walls.
I noticed the other people hanging about on the summit of Mont Blanc looking slightly miffed - not sure if this is because they are unhappy at finding a party on what they were expecting to be a peaceful mountain top or disappointed that they aren't getting an invite to join in!
> not sure if this is because they are unhappy at finding a party on what they were expecting to be a peaceful mountain top o
I may sound like a hater, but I would certainly understand the frustration of those having climbed Mont Blanc only to find a bunch of party-people in there (if that really was the case for their looks).
And a serious question: How do these people have money and especially free time for this?
Later edit: Before people start down-voting me, I found this comment of a guy who was among the "other" people on the top of Mont Blanc (meaning he was not invited to the jacuzzi party). He pretty much disapproves of it all, with quite good reasons (text is in French):
> Me trouvant avec mes deux clients au sommet du Mt Blanc ce 13 septembre, je ne peut que vous faire part de notre consternation devant la débauche de bruit et d'agitation ridicule qui polluait l'endroit ce jour-là. Est-ce paraître pisse froid que de ne pas partager votre enthousiasme pour cette réalisation qui contribue à rabaisser un sommet majeur au rang d'exutoire de nos névroses et théatre de nos délires les plus vains ? En a t-il subi, ce pauvre Mont Blanc, des idées absurdes : la tentative de descente en voiture, celle en poële à paella, une autre en VTT et j'en passe. Victime d'égos surdimmensionnés, les sommets phares sont chaque jour dévoyés par des personnes donnant de l'alpinisme une image aberrante (CF la tentative de l'ascension de l'Everest...en short ! Vous y verra-t-on bientôt en mailot de bain ?).Promotion dont nous nous passerions bien à l'heure ou nos effort tendent à rendre à ces montagnes leur véritable statut. Mes clients n'avaient-ils pas le droit de jouir au terme d'un effort que vous avez vécu, d'un sommet conforme ou presque à leur idéal ? Il me semble que cette façon de s'approprier un lieu au mépris des nuissances causées à l'égard des autres personnes qui le fréquente, celà sans autre objectif que de s'offrir un délire de potaches se situe à la limite del'incivilité. Salutations. Denis Crabieres, guide de montagne, secrétaire du syndicat national des guides de montagne
I understand the feeling, but I can't help seeing an undercurrent of "please don't make the mountain look easy/fun/silly or all the macho sunday-mountaineer stockbrokers who pay me won't want to climb anymore"
We got the same flack from the guides (and the police, but that was fair TBH) when we did the massive paragliding group landing summer 2012
Oh god don't get me started on the ESF... That's a classic cartel if there is one. Did you know that they don't let you keep the wages you own? All the money is pooled and then split at the end of the season according to seniority and number of hours. What a scam.
Not that I don't agree with the higher standards required - in other alpine countries you see a lot of anglo-saxon "instructors" who clearly wouldn't be able to pass the tests.
Well, personally I'm miffed about the banning of ski hosting - where they are very careful not to give instruction but it's great to have someone take you round and book restaurants etc.
Having said that, I know of one large French ski area that seems OK with it but I won't say which one it is... :-)
Here's the Google Translate to save others the trip:
Finding myself with my two clients to the summit of Mont Blanc on September 13, I can only share with you our dismay at the sound of debauchery and ridiculous agitation that was polluting the place that day. Is it seem colder than piss do not share your enthusiasm for this achievement that contributes to belittle a major summit to the rank of outlet for our neuroses and theater of our most vain delusions? As he suffered, the poor Mont Blanc, absurd ideas: the attempt to drive down, the stove in paella, another mountain bike and so on. Victim of egos surdimmensionnés, headlights summits every day misguided by people giving mountaineering aberrant image (CF attempt to climb Everest in shorts ...! You will soon do we see bathing Mailot?). Promotion which we would move us well on time or our efforts tend to make their true status in these mountains. My clients had they not entitled to enjoy after a strain that you experienced, a consistent top or near their ideal? It seems to me that this way of taking a place in defiance of nuisances caused against others who frequent it, it no other purpose than to provide a delirium of schoolboys del'incivilité is at the limit. Greetings. Denis CRABIERES, mountain guide, secretary of the National Union of Mountain Guides
So basically......damn those people who make this look easy and make our super macho profession look silly? I honestly don't think these are good reasons.
I'm sure there's lots lost in translation, but what I got out of it was more in the area of feeling that the sanctity of the mountain (in a religion-of-nature manner) was violated by "heretics".
How about hot tub in the Vatican? Is that inappropriate? It's a fun exercise to list the worst places where you might unexpectedly encounter a tub full of nearly naked drunk Europeans.
or because they'd been training for 6 months to make the big climb and they were suddenly confronted with the fact that for these guys it's so easy they brought a jacuzzi up with them ;)
I like that they're all wearing helmets while in the jacuzzi. Because, you know, it would be completely irresponsible not to. (They're probably more worried about knocking a helmet off the side by accident, if they were taken off, than the utility of wearing a helmet should the cables holding the jacuzzi break.)
The reason is that there are lots of people on the edge of the cliff fiddling around with carabiners and other bits of gear and it's quite easy to drop one by accident. Being hit by a lump of metal is pretty unpleasant. Climbing helmets are designed to divert glancing blows from falling objects, not save you from falling.
Often with sports climbing you'll see the person belaying (at the bottom holding the rope) wearing a helmet, while the person half way up the climb isn't - the risk is the climber will drop something on the person at the bottom.
The real issue is that a jacuzzi full of water weights a lot. The bridge is not designed for holding such a large load on the edge. A helmet won't help you for this, and a harness and rope attached to the bridge at the same point as the jacuzzi may not either.
I assumed 'jaccuzzi' was some sort of new programming language or framework that I missed out on, and that "suspended" was referring to a specific implementation clearly superior to non-suspended jaccuzzi ;)
Well to be honest, even though it is not a programming language, I would argue that this jacuzzi implementation is clearly superior to a non-suspended jacuzzi.
This reminds me of the article on bullshitting the other day. On the one hand this is useless play time that wastes resources. But it's also quite a big project. Everybody who took part in planning and executing it gained a lot of experience in project planning and management, the dynamics of working with people, how to work with their peers.
No matter what random challenge tomorrow brings this group of people is probably better equipped to deal with it than most social groups who have never tackled anything like this together. Of course they may not be great at handling the mundane, and that might be what drives them to hang jacuzzis off bridges.
Those are some high spirited friends, wish you could order them in mail just like that. But anyway, what about the permissions, is everyone going to start doing this now?
With the amount of effort clearly involved in such an operation, I think it is fairly safe to say that no, everyone is not going to start doing this now.
I didn't realise this. However, it would seem that it isn't as clear cut as you suggest:
(From Wikipedia):
The generally accepted highest summit is Mount Elbrus (5,642 m or 18,510 ft) in the Caucasus, appearing on both the Bass and Messner lists. However, because the location of the boundary between Asia and Europe is not universally agreed upon, its inclusion in Europe is disputed: if the Kuma–Manych Depression is used as geological border between Asia and Europe, Caucasus and Elbrus lie wholly in Asia. If the Greater Caucasus watershed is used instead, Elbrus' peaks are wholly in Europe, albeit close to the border with Asia. Mont Blanc (4,810 m or 15,781 ft), lying on the border between France and Italy in the Graian Alps, is seen by some to be the highest mountain in Europe.
The question that keeps running through my head -- how do you get back up onto the bridge, once you've left the jacuzzi?
Pulled up by winch?
Hand over hand climbing (ouch) or manually but assisted by equipment (e.g., I can imagine one-way sliders on the rope that'd let you climb with leg power)?
I did my share of rappelling when I was a teenager, but never had to climb back up the way I'd come with nothing but the rope....
Ascending single or double ropes is most often practiced in rope access, tree climbing, caving or technical climbing. Ascending a single rope will often involve a Jumar [1] and a camming device placed on your foot or chest. Ascending a doubled rope can be done with just the rope using Blake's hitch or some extra material and a Prusik knot.
Such imagined one-way leg powered rope sliders exist[1]!
They work well, but surely would be tiring and—after exiting a jacuzzi into a windy void—I'd have to imagine quite cold.
Very true -I guess the point I was trying to make is that if you find yourself at the bottom of a rope _without_ an ascender to hand, all hope is not lost. (though admittedly, I'd probably need a working internet connection to be able to remember how to tie a prussic ;) )
Good luck lifting 6 tons with a hot air balloon. (That's what this contraption weighs). Even a small one would be out. A four person hot air balloon can lift about 1 ton max, including all the gear, gas, burners etc. That leaves very little room for deadweight such as water, on the plus side you wouldn't have to take any ballast at all.
Are you using Hacker News Enhancement Suite on Chrome? I'm seeing the same thing with that configuration, but not when it's disabled (or on other browsers).
Hey Dan, what kind of problem do you have with the search (we recently fixed the back button + are also working on the small 320px screens support). I would be happy to improve it.
