Guest taken to hospital after metal object falls off TTD

Top Thrill 182 said:

...I suppose it was good guests and operators worked together to stop the ride before the next train was dispatched.

Given the apparent speed the signal flag was travelling, the train presumably failed to check in to or out of Block C, which would have prevented the next train from dispatching.

I wonder if the park suspected this proximate cause as early as Sunday...

Assuming the train would have failed to advance through Block C from the PLC's perspective, and that CP's maintenance crew almost certainly would have noticed what was missing fairly immediately, assuming they were able to inspect the train, and the early confirmation from the park, I imagine they knew within minutes exactly what happened. Obviously the "what" is the easy part, the "why" takes a bit longer to figure out.

EDIT: I give up on trying to fix the broken formatting... only "Block C" should have been linked, not sure why the whole remaining post ended up linked.

MDOmnis said:

I can see the investigation coming to a lot of different conclusions...

1) The wrong bolts were used. Although this isn't a "structural" piece of the train, it's important that it stays attached. Maybe the bolts used could not handle the constant vibration throughout the course of a season and one or both of them failed.

2.) The bolts were not replaced at a high enough cadence - again because they were thought to be less critical since they weren't structural or load bearing.

3.) The tightness/integrity of these bolts was not checked at a short enough interval.

1) You're telling me they used the wrong bolts for 18 years and got away with it the whole time? Not buying that conclusion of yours.

2) Maybe. It's hard to tell from the one picture circulating the internet, however it seems that the holes in the bracket are conical. If they are indeed conical then this could have very well played into the failure. I stumbled upon an interesting read about lug nuts and wheel studs on Facebook last night about causes of failing wheel studs on racecars that actually had good explanation and discussion surrounding this.

Long story short, it's nearly impossible to have the conical faces of the mounting surface and head of the bolt match up perfectly. As you tighten the lug nut, or bolt in this case, it has interference at a point or points in its seat before the whole thing eventually is seated. This causes uneven tension on the stud, or bolt in this case. After a rather small amount cycles, if you will, of loosening and tightening you quickly begin the elongate the threads. And the clamping force drops off alarmingly quickly. In the case I saw reference, after only five cycles of taking a lug nut on and off the clamping force had decreased by around 50%.

Again, hard to tell from the crap picture that's on the internet, but if it is indeed a conical mating surface for those bolts then I would find this to be a plausible part of the investigation.

3) They were checked daily. And once again, it worked for 18 years. Highly unlikely.

MichaelB said:

Again, hard to tell from the crap picture that's on the internet, but if it is indeed a conical mating surface for those bolts then I would find this to be a plausible part of the investigation.

You're telling me they used the wrong mating surface for 18 years and got away with it the whole time? Not buying that conclusion of yours.

Someone earlier in this thread listed the plethora (5 points for using that word) of incidents that happened on TTD. Throughout the years, these incidents have become more severe in nature.

Wouldn't it be a smack in the face to this victim and previous victims of less severe incidents if CP just said, Oh well, we'll fix it and reopen next year?

Again, this isn't just an isolated event with TTD. A cable has snapped, causing minor injuries due to metal shards. A tire went flying off.... and I'm sure there are other incidents I'm missing.

Even if proper grade hardware is used, performance isn't guaranteed per-say. Flaws are possible (voids and other defects) that can jeopardize the hardware.

We have had flight hardware fasteners (highest quality level required with material certs, testing, traceable source, etc...) be defective before upon installation... For example, a few weeks back we were applying the appropriate torque and the head of a fastener sheared completely off. We were not pushing these fasteners to their limit by any means. After investigation, we found the undercut/relief groove between the top of the thread and the fastener head was at too small of a diameter, reducing the strength significantly. I don't remember off the top of my head, but I calculated something like a 40-60% reduction in strength. Even if the fastener torqued up properly, it most certainly would have failed under vibe/shock testing. Which would have been far worse for us, at least. We ended up ordering in all new hardware and discarding that lot and pre-inspecting each for the appropriate diameter of the relief.

Things happen... Unless you do NDT on each and every fastener, your hoping redundancy (having two fasteners when only one is required, for example) and FOS in design can prevent critical failure like this. If this was a bad batch of hardware, there is little that could have been done to know ahead of time without testing each and every fastener, which isn't common by any means.

Not knowing really anything else on this one, my bet is on defective fasteners or installation (overloading the fastener with the wrong torque value or a combination of the wrong grade fastener / torque).

djDaemon said:

You're telling me they used the wrong mating surface for 18 years and got away with it the whole time? Not buying that conclusion of yours.

Hurr hurr, you can mock me. Do you want to have an actual technical discussion about what I'm referring to or not?

The short answer is no. The long answer depends on your response to my aforementioned question.

I'm mocking your snarky assumption that Matt was suggesting they've been using incorrect bolts since the ride opened. It seemed to me he was implying an incorrect grade bolt was used during the train's most recent seasonal rebuild. Of course I could be wrong.

But anyway, why in the World would they use a conical mating surface on what appears to be a very simple part whose function does not require complex machining? This is not a component that requires precise mounting.

Edited to add... I suppose clearance would be a reason for a countersink, but is this thing mounted in such a way that they need that much clearance?

Why are we analyzing this so much and arguing! It's a mechanical device they all fail at some point, it just happens. I read an article a few minutes ago that stated that parts come off rides more often than we think, this poor women was in the wrong place at the wrong time. It is sad, but it's not a matter of if a part will fail it's really when.

^With. all due respect, I'd call it analyzing and debating. That's what these forums are about. And if you can find a forum where it's all Kum ba yah and Barney songs, then have at it.

2020TpForSale said:

Wouldn't it be a smack in the face to this victim and previous victims of less severe incidents if CP just said, Oh well, we'll fix it and reopen next year?

I don't think so, no. I assume this person will likely be compensated for damages, and the park is doing its due diligence to understand what happened and eliminate the failure mode. While it may seem frustrating, it seems like this is simply a tragically unfortunate accident. I don't think re-opening the ride after completing a thorough investigation and resolution is insensitive.

Last time I checked Big Thunder Mountain Railroad is still operating at Disneyland, and what happened on that ride was...well...worse.

I also don't think it would be a "slap in the face". The ride is complicated, and it has a complicated history.

That said, I would not be surprised either way with regards to its future, but that's a different debate altogether once the puzzle becomes more clear.

^I feel so small in my world of knowledge regarding coasters compared to some of you! I've learned a lot. But unfortunately, for various reasons, it usually goes in one ear and out the other!

2020TpForSale said:

Someone earlier in this thread listed the plethora (5 points for using that word) of incidents that happened on TTD. Throughout the years, these incidents have become more severe in nature.

Wouldn't it be a smack in the face to this victim and previous victims of less severe incidents if CP just said, Oh well, we'll fix it and reopen next year?

Again, this isn't just an isolated event with TTD. A cable has snapped, causing minor injuries due to metal shards. A tire went flying off.... and I'm sure there are other incidents I'm missing.

Raptor beheaded someone and it's still running.

That was human error, though, and nothing to do with the ride itself. It's different when something on the ride itself breaks that leads to human suffering.

If you jump out of a log flume and almost drown, it's not scary. If a flume ride flips over and traps multiple riders under the water, it's scary.

Shoot the Rapids opened right back up after that as well. For a little bit.

It's not wrong to say "this isn't the first time" for Dragster, because it's not, and in one instance (the wheel) the park dodged an enormous bullet.

Well, to be fair, that person trespassed into a low zone. The guest in this case was in the queue.

EDIT: What he said.

^^^Apples and oranges. That was NOT raptor's fault.

Do we all agree that it wasn't Raptor's fault?

;)

Fun trivia: That guy was a teacher at my daughter's school. No, I didn't know him, but it made the experience even more surreal.

^Do we all agree that we all agree that it wasn't raptor's fault?

I find it hard to believe they'd get ride of TTD. It's just so iconic

I doubt they close it for good unless they find something inherently wrong that they cannot confidently fix. Would imagine there are some significant changes to the adjacent queue and midway though. Addition of fencing, walls, canopies etc...