Analysis of the Julianabrug Crane Accident in Alphen
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- Опубликовано: 8 авг 2015
- Two cranes collapsed when lifting a heavy load bridge part in Alphen an den Rijn, Netherlands.
They were mounted on two vessels, and were intended to get moved to the place, where the bridge part should get placed.
Lifting up the load, the smaler crane turned and fell into the houses next to the channel. The other one was torn by the load, which also landed on the roof of the houses.
IMHO a very challenging task, and for civil engineers for sure bearing high risks. We are trying to make an analysis in this clip.
Two different mobile cranes on two pontoons on two different positions.
I think also the wind was a factor. It was 3 a 4 beaufort directly on the bridge.
The section is in the state of an "open bridge" and I think it was the planned way to insert it into the rotation joint.
But I am curious, whether the maneuver of bringing the bridge section to the other side of the vessels would have worked without difficulties. It would had to pass inbetween those two cranes, avoiding any excentricity.
Ex rigger,crane worker here.......sometimes it just dont look right....this was one of those times...even if the calculations had been done...too many pivot points and in water...mmmmm glad no-one was killed.....get the vacuum cleaner out though!
The crane to the rear is far to close to the edge of barge where it pushes the barge down and dips to far carrying the weight over with it to low and of course this was already a dangerous idea on a liquid boiyant medium
Looking at the basic video footage, the problem appears to be an inherent lack of stability in the pontoon/barges; a secondary issue with the smaller crane appearing to slew too fast; and a further issue that neither crane appears to have been lashed to the barge.Once the weight of the load is taken by the hook, there is a virtual shift in the combined centre of gravity from within the barge (and an initially stable equilibrium) and the centre of gravity (CoG) moves towards the jib-end of the crane. This virtual shift may well have reduced the metacentric height to zero (effectively, zero stability) and once the slewing of the load commenced it would have been sufficient to destabilise the whole rig. The resultant loss of stability of the smaller crane/barge rig has caused the initial collapse - which, in turn, has directly affected the larger crane.There may have been some slack ballast tanks (part-filled) whose free surface moment may not have been allowed for in any stability calculations by the engineers.Obviously, we do not know what the initial state of stability is/was, nor what presumptions were made by the engineers, if any, of the weight transfer.There may also have been problems with the ballasting of the barge tank systems, and any unaccounted free surface effect would detrimentally affect the stability of the barge.Sadly, it does not look good from a professional point of view, and there appears to hae been many fundamental errors.
In other words don't put a mobile crane on a moving surface. It will end badly.
I was there that day. and it was pretty wind. and the ponton was a bad place to start from anyway.
Why were the cranes closer to the edge of the barge and towards the opposite end of barge? They could have used the tug boat as anchor/counter weight if they would have situated them closer to the front or like high rise cranes .. they should have place counter weights on the opposite side of the barge to counter the weight and movement - I agree having 2 mismatched cranes was not a good idea- soo many mistakes on this one. I can't believe someone signed off on this. This is what happens when you hire like minded people or relatives.
The crane driver obviously wasn't really aware of what the challenge of this job was, but you should put more emphasis on the fact that in the moment the smaller crane started rotating with most of the load hooked on, its pontoon also inevitably bends over due to the shift of the center of gravity. This is what makes the whole situation fatal.
A tandem lift is always something one should prepare with painstaking care, but NEVER based on the edge of two pontoons floating freely in the water without any ground suspension.
I wonder how such a serious mistake could happen in a country with so much experience in offshore construction.
I’m an ex rigger with large cranes. A quick look before the accident sends warning bells…it LOOKS wrong and experience tells me it usually is. Crane positioning and size difference stands out. The pontoon is very unstable….anyway my comments mean nothing to anyone. All I know is I hope the chief engineer on this job ran to the dole queue after that almighty balls up!!
De windbelasting was best hoog die dag en de windkracht grijpt aan op het hoogste punt van de kraan resulterend in maximaal moment op de pontonvloer die vervolgens gaat kantelen om nog meer hefboom/doorzwaaieffect te leveren... patsboem!
everybody seems to have a idea about this failure
If they came and ask me if that would work before they attempted it i could have told them it's a fail... im really curious are the people responsible for the operation really that stupid to think two cranes on a narrow boat are not going to fall and destroy shit... im losing faith in humanity...
True, this is why it happend.
It was also mine opinion one month ago.
seams everyone's a crane operations special here. ... LOL
Heb nog nooit kraan machinisten zo snel zien draaien met zware lasten. Dan kun je niet meer terug en evalueren en/of bijsturen. Ver voordat het verkeerd ging kon je al zien dat de boot scheef ging hangen. Er was een probleem met een kabel en ook dan ga je terug. Te weinig toezicht en communicatie ... mensen liepen gewoon weg tijdens het draaien.
The operator was not swing too fast, the barge began to turn and he had no chance to stop that progress. Are you a crane professional? I guess you don't...
Rene Fermer no, I am a civil engineer for steel constructions.
In the video I did not blame the crane operator. IMHO some facts weren't calculated correctly - or the smaller crane had a technical problem.
Those cranes have a lot of intelligent security mechanism, bt those pontons, they were placed on, are just stupid tins :-)
I agree that there has been a technical problem, but I don't think that it concerned one of the cranes.
+Peter Randeler From what I've read on the website of company they where hired from, these pontoons do have separate ballast tanks.
When you look at the video, it looks like there were movable pumps installeled on the decks.But maybe the didn't use the ballastwater in the right way...
Crane experts believe that the second crane was too small for the job and it went into safety mode. The operator didn't have enough time to disengage the safety mode and stop the crane from failing.
You should look closer to the video. They start by lifting the load, then both cranes tilt the booms up and the load starts to move sideways. A few seconds later the right smaller crane turns left, this is the point things start to go wrong and people panic. The load starts to move faster toward the cranes and the pontoon starts to tilt moving the boom top leading up to the collapse.The big question is why only the smaller crane turns left just after the boom tilt maneuver of both cranes. Was it the driver, or the crane's computer responding to the load shift and/or tilting of the base (level of the pontoon) Also the smaller crane was closer to the load making it more sensitive to load center stability which made things worse in my opinion.
+Michel de Groot Michel - it is an visual illusion, that the smaller crane is turning. If you take a closer look to the top of the boom with the pulleys, you can see, that the shape stays the same.
IMHO the boom is forced into that position - the hydraulic lift is getting traction forces, or too less pressure.
I agrree, that the cranes were placed in different distances to the load - and if you watch my other video, the different placement on the pontoons made it even less calculable.
+Peter Randeler No, look at the cabin of the smaller crane and do an overlay or shade cancelation and you will see the shade change. You cannot see this turn from the boom top as the viewing angle is perpendiculair to the boom. The top of the boom starts to shift to the left after this turning as the load starts to move towards the crane in reaction to this turning.
+Michel de Groot I tried to evaluate that - and IMHO it is just the shadow of the deck, which is moving between sun and the cabin. At first I also thought, that the crane was turning. But as the boom has a rectangular shape, this should have been visible there.
There were people on the roof next to the cranes. It was in hope, that they also made some videos, to get another view of the scene.
+Peter Randeler I,ve made another video montage withe
static reference points.
And I thought : should I put it on RUclips ?
I threw my project away(maybe I should have uploaded it)
,but i came to
the following conclusions:
The cranes didn't turn at all
The cranes were not defect.
The tugboat behind the smaller pontoon was making a correction manoeuvre causing extra instability.
The biggest crane was out of horizontal balance.
And.. It seems that the wind is probably the main cause of it all.
The wind was rather sure coming from the west,force 3,
exactly from the direction where you except it to come from ,
in the case it has blown the bridge and the pontoons in the
direction they have fallen.
Almost nobody is thinking about that.
Almost all what you see from the camera point of view is optical
illusion, because it's so far away,what makes it look if the cranes
were turning.
+AM I agree with you: The cranes did not turn and I don't think that one of them was defect.
The manoevre of the tugboat, is caused by the pontoon in the background. When the pontoon is listing more, it is suddenly getting free and turns into upright position.
But I am not sure, whether the wind was playing a role. If the wind is causing the bridge deck to move, the bigger crane should also move, not just the smaller one.
For the bigger crane's horizontal balance - if you mean, that it was out of balance in the length direction of the pontoon, then that is what I tried to explain in my second videoclip. This balance together with the wind may have caused the horizontal movement of the deck towards the smaller crane.
the news story: www.rt.com/news/311458-crane-collapse-hollande-house/
Everybody in the Netherlands thinks the crane just collaps, but is not the whole truth.
He collaps because it was broken (at 2:27)
yes, it broke because of the weight pulling in a non-down angle
the bridge section got hit by a gust of wind. look at trees in background . it became a huge 200 ton sail . should of had strong guide ropes mmmm
Ian Kenny Guiding mechanismens could prevent the swinging of the section. Although - if the wind caused that movement, IMHO it would have effected both cranes.
one crane smaller it would push that out of way and then the barge tilting with extra weight our sail is really moving now eeee run
They did a similar lift some time ago: ruclips.net/video/jSh8CYSYEAc/видео.html
So there was experience of having large cranes on barges. Makes this even more strange.
+sebofo In contrast to that, one of the cranes was placed on solid ground. And the bridge deck has not the weight of the new one, as the counter weights are not attached to it.
Putting one of the cranes on ground would have lead to more stability.
Nothing strange in this accident. The very first thing you learn on a basic crane operators class, is you NEED a solid foundation for you crane. A floating barge is very far from stable. The ONLY way this would have worked, would be if the barge had outrigger legs pushed into the seabed.
This was doomed before they turned up on site, it was never going to work. Narrow floating pontoons and two different size cranes, in effect competing for the load. Bonkers. I think the planning team must have got bonged up in a "coffee" shop and completely lost their grasp of basic physics.
No job for civil engineers: This is a job for Heavy Lift transporters like Jumbo Shipping.........penny wise pound foolish.........
+Limoncello666 So in your opinion it was the fault of the crane company? They are responsible for that mess?
I don't like and want to point fingers at persons.Always easier for people standing by to judge.But if you have played a bit in your past (I'm not a PS IV generation....)with toys and cranes and what we used to have in EU (Meccano or Fisher Technik) you can see that was meant to go wrong.Like the publisher of this movie already implied,mobile cranes for solid ground used on a movable pontoon is not a great start.Are the pumps be able to"counter" ballast in time when the cranes are swinging?On seagoing ships loading and unloading their cargo you have a ballast and loading computer on board ,calculating from beginning till end giving all strength conditions of the vessel,list,bending moments etc.
Draught of the pontoons,:I have no idea but guess not even 15% of it is in the water compared to what(crane and bridge) is above the water
For me not very clear to see is when or what happened first,breaking or swinging uncontrolled at a speed way too high.
It's not a job very rare in The Netherlands but there are unfortunately a lot of "managers" (bright young graduates) in charge who are able to find the best solution money-wise...cheap CHEAP CHEAP.And who decided to ask a company to do this kind of job and convinced others that these are the correct people to do it should be heard as well and not hide him/herself behind the performing company who said :yes we can do that.
I don't believe that just a mayor of a small town kind decide on his own who will do the job.Director ship of the province has civil engineers and they most probably are responsible of how it will be done.Crane company surely has to do all the calculations and check their possibilities with the equipment and circumstances.Who ever made this performance and showed the "masterplan"to the involved parties will be asked questions no doubt.All parts of the crane etc. will be checked afterwards,material analysis,welding seems,butts and so on.
In any case the old bridge has been removed before as well so that went OK(?)
It will take time to investigate what has happened actually,so very easy to say this and that he did ,she did.I don't know the features of all the used equipment but it is in my opinion just very underestimated.....The cranes on 2 pontoons gave me that first impression.
I cant believe the Crane Operators allowed this ??? I'm no Engineer but that was fucking insanely moronic. about 10 to 12 Million $'s worth of Crane condemned to parts salvage.
The report of the investigations is quite interesting, as it is said there, that due to the high position of the center of gravity the whole construction would have never worked. The collapse was inevitable.
Also the investigation report said that the smaller crane's boom actually bent backward under the stress which was also a factor.
Pourquoi ne pas avoir stabiliser les deux barges? Deux pieux part barge enfoncer jusqu'au fond aurait éviter se carnage !!!
shoulda had american engineers
+Enlighten Beats
For nice swingy bridges
Yoe uuuhh, speake english ferry well