Does anyone have any thoughts on this failure? I’m curious what the typical inspection schedule and process is for a roller coaster like this.
I’m also curious about the root cause of the failure. I have a guess, but it would be interesting to see an actual failure report. I don’t expect to see it in the news, though.
Here is a video of the crack moving as roller coaster cars go by.
Someone also got a photo of the crack a week prior before it had fully propagated through the support.
That looks like a fatigue crack, which makes sense for a roller coaster.
The ride should be closed.
Interesting to see a fatigue crack on a coaster this new.
Yeah, but the ride has been open for years and the left end of the crack seems to be coming from the weld between the vertical and diagonal hollow structural shape in an area that would receive cyclic tension loads.
It could either be a bad weld or bad detailing.
A wise senior engineer once told me, “There’s never only one problem. There are at least two and they work together against you.”
My armchair quarterback take is that there was a stress concentration at the weld, and also that inside corner wasn’t well painted so corrosion was a factor in initiating the crack.
The Wikipedia article for the coaster says the crack started along the weld line, so my current hypothesis is a faulty weld.
I know I’m just an out-of-work aircraft repairman so the next thing I’m going to say is probably insane, but if it were my roller coaster I wouldn’t re-open it to guests until I’d replaced that support column and done some NDT on that section of track as well as all the other support columns. I’d likely have nightmares for years about some weld somewhere failing. See why I don’t work on planes anymore?
You aren’t wrong, but they are also going to need to verify the fatigue design of that detail. That connection detail is rather rigid, so the model they used for the design of that weld may not have accurately modeled the stress at that weld.
This is the kind of issue someone can get a PhD trying to solve.
Not insane at all. I hope an NDT contractor is going to get some business out of this incident.
I don’t see corrosion as a likely issue; there is no staining of the paint in the location of the crack and the crack likely propagated from an area protected from water by the joint to the track.
A stress concentration at the weld would be due to poor craftsmanship, which I mentioned earlier.
Good point about the lack of paint staining.
So the coaster goes around the corner and the load gets transferred to those supports? Looks like. There’s more than one support on the bend but the video shows that that support is basically not a part of the structure anymore and it is at the apex of the bend. The supports on either side are now having to tolerate different stresses that they may not have been designed for, same for the track. I find it highly unlikely that this was signed off on. “That’s a redundant support, we’ll fix it when we can?”
Just looking at the picture
- the crack is open. Meaning the pillar went through traction / compression all the time in use.
- the weld broke due to fatigue then the crack propagated.
I’d guess poor adjustment, possibly due to the pillar sinking, and an issue in the weld. Issues in weld can have so many causes, but supposing the welder knew their job, it’s probably a poor welding procedure, poor NDT (but then 100% radio/UT is expensive for a roller coaster), maybe lack of pre/post heating…
