Dreamworld becomes Nightmareworld

[raptor1956]

I just saw an article about a theme park ride accident near Brisbane that claimed the lives of four people but that two teenage girls somehow managed to survive.  They did not do into the gruesome details beyond saying the dead were killed by a conveyor belt.

http://www.cnn.com/2016/10/25/world/queensland-theme-park-fatalities/index.html


Brian

[TerraHertz]

It's one of those 'best not to google it' things.

[raptor1956]

Yeah, I'm not interested in seeing gore and the stuff you might see on LiveLeaks etc -- just reported what I read about an event taking place in the home of EEVblog.


Brian

[EEVblog]

It's one of those 'best not to google it' things.

AFAIK there is no gore to be seen.
Yes, 4 people were killed and two kids survived (the raft holds 6 people). Sadly the kids of one of the women killed were watching as it happened (the conveyor belt is right near the public viewing platform)
The raft got hit by another raft and flipped, two people trapped under and two people flipped out, all 4 of whom were killed. Unknown how the two kids survived.

What I find remarkable is how it happened. This is a fairly sedate rafting ride you can take 2yo's on (I took Sagan on it last year) and has been operating for decades. So seems remarkable that an incident like this only occurs now.

[EEVblog]

It's the worst theme park accident since the Luna Park fire in 1979
https://en.wikipedia.org/wiki/1979_Sydney_Ghost_Train_fire

[aargee]

Actually they were all adults killed. Looks like one jammed on the start of the conveyor and another came up on the rear and overturned it.
The ride has been there since the mid 80s. Been on it with our two when they were munchkins many years ago.

Stuff happens, wrong place at the wrong time. 

[EEVblog]

Stuff happens, wrong place at the wrong time. 

Yep, freakish conditions. Surely these boats have bumped into each other at that spotted many times in the past?

[zl2wrw]

Yeah, I'm not interested in seeing gore and the stuff you might see on LiveLeaks etc [SNIP]

Yep, I second that.

However, I am interested in the cold hard details of what went wrong, and what mistakes were made - I'd rather learn from other's mistakes instead of making the same mistakes myself...

[StuUK]

wow, 9 posts in and off topic already 

[EEVblog]

wow, 9 posts in and off topic already 

Post deleted.

[EEVblog]

However, I am interested in the cold hard details of what went wrong, and what mistakes were made - I'd rather learn from other's mistakes instead of making the same mistakes myself...

I'd be a bit surprised if mistakes were made here. I'm guessing the finding will be freak unforeseen accident.
These boats are designed to bump into each other, although IIRC that's not the normal mode of operation, but not unusual and would have happened countless times before. Might just be a case of bumping into each other at the wrong point and the wrong angles etc.

[Brumby]

From what I have seen on tonight's news, the accident occurred between two sections of the conveyor system.

The conveyor section at the front (conveyor A) failed and the raft (call it Raft 1) on that one rolled back.  The conveyor section behind (conveyor B) was still operating and tried to push the raft (call it Raft 2) that was on it into Raft 1.  Raft 1 didn't move and the front of Raft 2 then lifted up over the back of Raft 1. 

This is when the problem got serious.

There was a gap between the two conveyor sections (about 40cm, I believe).  Normally a raft will get moved by Conveyor B which will then cross the gap and Conveyor A will take over and continue to move the raft.  When rafts pass over this in normal operation, the gap is quite insignificant - but what was happening was not normal.....

As the front of Raft 2 rose up, the rear dropped down and slipped into the gap.  The front of Conveyor B caught the rear of the raft and dragged it into the gap.

I'll say no more....

[Jeroen3]

I couldn't believe people were killed in such ride at first. But it looks like there are large gaps in the conveyor. I can unfortunately imagine that you can get stuck in those gaps.
There is a similar ride in the Netherlands, but the gaps on the conveyor are smaller.

[TerraHertz]

Yeah, I'm not interested in seeing gore and the stuff you might see on LiveLeaks etc -- just reported what I read about an event taking place in the home of EEVblog.

I wasn't referring to visual gore, there's none.
It's the engineer's visualization of the accident process, once you learn the mechanism, that would best be skipped.
Probably OK for those without vivid imagination.

[raptor1956]

It's pretty hard to envision every possible failure mechanism and provide controls to prevent it.  And, even when you can envision it it may be impractical to develop a control to prevent it.  We don't live in rubber lined rooms and thankfully so.

With what little we know at this point it's safe to say the conveyors played a role though just exactly what and how has yet  to be detailed.  I wonder if they have torque monitoring on the motors driving the conveyor and if so what the torque profile looked like before, during and after.

Ultimately four people lost there lives and the two children that survived witnessed something you would not want a child to endure.  Keep them in you thoughts...


Brian

[Jeroen3]

It's the dark side of engineering. Some things have to fail for us to learn and improve.
We've lost many planes to get to current standards.

[Cyberdragon]

It's pretty hard to envision every possible failure mechanism and provide controls to prevent it.  And, even when you can envision it it may be impractical to develop a control to prevent it.  We don't live in rubber lined rooms and thankfully so.

With what little we know at this point it's safe to say the conveyors played a role though just exactly what and how has yet  to be detailed.  I wonder if they have torque monitoring on the motors driving the conveyor and if so what the torque profile looked like before, during and after.

Ultimately four people lost there lives and the two children that survived witnessed something you would not want a child to endure.  Keep them in you thoughts...


Brian

Torque sensing might work, but it's finicky (how much torque is dangerous?). A better system would be proximity sensors of some sort (lidar, sonic, radar) on the end of each conveyor and a little way before the end of the back conveyer to monitor the passing rafts and check for obstructions.

[Brumby]

Rather than getting fancy about sensing if something might be falling down the hole - why not just block the hole?

I would think a better system would have been to fill the gap with a simple bit of framework.  It could be an inch below the normal path of the rafts, so it wouldn't interfere with the exiting operation and mounted with a few bolts that could easily be removed for maintenance.

[dmills]

Thats the fix I would instinctively try for, passive safety is almost always better then active systems.

Apart from anything else some poorly trained operator is less likely to override a passive safety system (Poured concrete also trumps bolted on metal here if you can manage it).

See the accident at Alton towers in the UK where a rollercoaster had multiple cars in movement at the same time (Well it increases numbers of riders per hour) with railway style block interlocking for safety. While fixing an issue someone overrode the interlocking with a stopped car part way around the track).

The automation know there was a problem and was holding the next car waiting for the block ahead to clear, but the maintenance "Engineer" (Who had not read the O&M manual, and had not actually been out to eyeball the blocked section) 'knew' better.

Result of the coming together, several teenagers with leg amputations and a £5M fine for the operating company plus civil settlements to come.   

The sort of thing that any engineer is both shaking their head at and quietly thinking "There but for the grace... go I".

Regards, Dan.

[jonovid]

a final word from Me . looking at the role of electronics in amusement park rides.
situational awareness of passenger unit separation and some type of automated alarm system may of saved lives here. and is probability is true of all amusement park rides. that use independently moving Passenger unit's on the same shared Line. be it gravity propulsion and or motorized.

[nctnico]

Rather than getting fancy about sensing if something might be falling down the hole - why not just block the hole?

I would think a better system would have been to fill the gap with a simple bit of framework.  It could be an inch below the normal path of the rafts, so it wouldn't interfere with the exiting operation and mounted with a few bolts that could easily be removed for maintenance.

I agree. Something like that is simple to make and prevents a raft from being pulled down. It still doesn't prevent a raft from flipping over. IMHO the conveyor belt should be fully closed so people can't fall through it. As Jeroen3 noted there is a similar ride in the Netherlands and IIRC the conveyor belt is fully closed (*). You could walk on it if necessary. There are European safety regulations for conveyor belts and I'm quite sure these also apply to amusement park rides.

Edit: * The belt is closed:

[StuUK]

If wonder if Disney are reviewing their similar rides?

https://youtu.be/Jdp_YAFcqtU?t=370

[@rt]

In my 20's I bashed my face on whatever surface was in front of me on the log ride as it hit the water at the end of its last drop. It hurt, but I didn't know I had blood all over my face. The way out after the ride is over leads you straight past the que of people waiting to get on next. They all looked at me in horror, and the staff were eager to shuffle me on out of view. Not once did any staff ask if I was ok, or offer any first aid. I was fine, but no one observing could have known that.

[Shock]

Was reminded of this

[StuUK]

BIG Difference, the guy was in control of his ride (or not if you get my meaning) and was just being a wanker and clearly not obeying the signs or maybe couldn't read German but still a wanker either way...