Cal/OSHA blames both Knott's Berry Farm and Intamin for Xcelerator accident

Posted Wednesday, April 28, 2010 1:23 PM | Contributed by Jeff

A state investigation found that a 2009 roller coaster accident that injured two riders at Knott's Berry Farm could have been prevented with proper maintenance, casting blame on both the theme park and the ride manufacturer.

Read more from The LA Times.

For video of the accident, go to YouTube.

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Wednesday, April 28, 2010 1:33 PM

If Cal/OSHA is to be believed, this sounds like a Three Stooges level of ineptness on both the parts of Intamin and Knotts. For this kind of snafu to happen, the powers that be at the park must not even have bothered to go over the operating and maintenance instructions with the manufacturer. And the manufacturer must not have cared whether its customer was properly informed about correct usage of its product.

This certainly doesn't give me a warm, fuzzy feeling about riding Intamin attractions at Cedar Fair parks.


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Wednesday, April 28, 2010 1:52 PM

What this tells me is that the State concluded that it just broke, and the only real issue they could come up with in a six month investigation was that Knotts was 19 days late with a biannual inspection. And knowing the reliability of that ride, Knotts probably justified the delay by noting that the ride had probably been out of service at least 20 days in the six months leading up to the incident: I'll bet they have their own service schedule based on operating hours or total number of launches.

But what kind of instructions do you expect the manufacturer to provide on the maintenance of a first-of-its-kind prototype system? Cedar Fair, and Knotts in particular, probably knows more about the operating characteristics of that ride than Intamin does.

There is plenty of blame to go around, but the news article makes it sound like the State is treating Xcelerator, and the relationship between Knotts and Intamin, as if this is a Tilt-A-Whirl where there are thousands of rides out there dating back more than 80 years and the manufacturer therefore knows all about it. This is a one-of-a-kind ride that was the first of its design and probably the only one built with some of its launch characteristics.

My conclusion is that it took the State six months to reach a conclusion that they could have probably reached in about four days. Absent a more detailed analysis of the incident, I've got to wonder what they have been doing all of this time. I don't dispute their findings, but I don't really see how this is a 'win' for ride safety, either.

--Dave Althoff, Jr.

    /X\        _      *** Respect rides. They do not respect you. ***
/XXX\ /X\ /X\_ _ /X\__ _ _ _____

Wednesday, April 28, 2010 2:00 PM
Lord Gonchar's avatar

RideMan said:
What this tells me is that the State concluded that it just broke...

Some of us came to that conclusion the day it happened.

Stuff happens. This qualifies as stuff.

Wednesday, April 28, 2010 3:10 PM

That's my point. Why did it take Cal/OSHA six months to conclude what most of us figured out in a few hours? When Cedar Point had a comparable incident on Dragster (albeit with a lot less damage to the train) I think they had the ride running just a few days later. What did Cal/OSHA come up with that the ODA did not?

Or are we supposed to believe that the longer an investigation takes, the more comprehensive it is?

--Dave Althoff, Jr.

    /X\        _      *** Respect rides. They do not respect you. ***
/XXX\ /X\ /X\_ _ /X\__ _ _ _____

Wednesday, April 28, 2010 3:46 PM

What DOSH was doing was billing Cedar Fair $125/hr for the investigation. Probalby covered the Anaheim's office expenses for the next year.

Wednesday, April 28, 2010 3:46 PM

That's because before they could release the report it had to be signed in triplicate, sent in, sent back, lost, found, queried, subjected to public inquiry, lost again, and finally buried in soft peat for three months and recycled as firelighter.

Wednesday, April 28, 2010 4:31 PM

These rides still scare the crap out of me simply due to the complex launching systems involved. So far, only Storm Runner has made it though incedent free. That doesn't give me a great feeling for Intamin Rockets.

Wednesday, April 28, 2010 8:20 PM
Jeff's avatar

Cal/OSHA is run by Vogons?

If they're really only inspecting the cable once every six months, that would be shocking to me. I'm not suggesting that they need to inspect every single inch, but you'd think that they would at least check the connection points maybe even ever day. They've had enough rides with cables break (chain-wide) at this point that I would think they'd know where to look.

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Wednesday, April 28, 2010 11:07 PM

This is a bi-directional system that always stops in the same locations. Half an hour examining the system and a reasonably competent person could predict the likely failure points. Heck, *I* could probably do that, and in this area I would not consider myself a reasonably competent person. But Cedar Fair has had a lot of experience with wire rope failures which means they are beyond reasonable competence. They know exactly where these ropes are going to fail, and I have every expectation that they do know what to look for and where to look for it. I have to think they are looking in those places, at least informally, regardless of what the service manual says.

The trouble is, an inspection only tells you what the part is doing at the time of inspection. That does not necessarily tell you when the part is about to fail. It only tells you it hasn't failed yet. Depending on the precise failure mode, it could be possible to look right at the failure point right before the critical launch, and not see anything out of the ordinary. The bottom line...stuff still breaks.

That's my opinion based on what little I know of the way that company works.

--Dave Althoff, Jr.

    /X\        _      *** Respect rides. They do not respect you. ***
/XXX\ /X\ /X\_ _ /X\__ _ _ _____

Thursday, April 29, 2010 7:31 AM

How about that, the ODA outperforms a larger regulatory agency!! I agree with everything said and am still trying to figure out why other materials haven't been tried/tested yet on Intamin's part. Or why they didn't re-invent LIM/LSM technology to fit the bill. In my opinion no one should ever feel good about Rocket Coasters!
Having to work with the EPA on a monthly basis I can tell you the way these regulatory agencies are structured is not efficient. Based on my experience, the person "doing"the investigations isn't the person responsible for determining end result. This delays the process as investigators gather data, forward the data to college interns who then sort it and process it. Then it goes to a panel and they determine cause/failure and retribution. This is where the timing goes out the window. The more data the investigators collect just implicates results.
Maybe ODA took the Occam's Razor approach as opposed to the village cop!
A machine is only as strong as it's weakest component, essentially you have the worlds most expensive cable around $20 million...That's a record CF should advertise!
I'm curious to know if Intamin had consultants involved with Cal/OSHA during this process.

Ride one of the most sophisticated roller coasters on the planet built by the lowest bidder. Hey it worked for NASA

Last edited by JoshuaTBell, Thursday, April 29, 2010 8:30 AM
Thursday, April 29, 2010 7:54 AM

Jeff said:
Cal/OSHA is run by Vogons?

At least one that I've met did have that look.

This "new" inspection method isn't really new. It's been used on aerial tramways and ski lifts for years. It does find breaks inside the rope, that you can't see with your eye.

The problem is, it uses a set of coils, and it can't see up to and inside connections. It works best for spliced ropes, where you can run the whole rope through the system.

So now you have to guard against the technicians trusting the magic box to tell them the rope is bad, and missing a failure where the magic box can't see.

Last edited by Power&Control, Thursday, April 29, 2010 8:29 AM
Thursday, April 29, 2010 8:01 AM

Count me with Jeff on this, Yes its per Manufacturer Recomendations but.

Every six months on high tension cable? WTH?????? Lets not forget that MF has had the cable snap twice as well as TTD's inccident.

I really am confused as to if CF launched investigations *The first time it ever happened?*

I guess its always possible for it to break on its first launch or hundred thousandth *Stuff happens* But the fact that its happened multiple times concerns me. I said from the beginning that a cable system was iffy at best. Go to Youtube and watch the cable snaps that happen on flight decks of aircraft carriers. Increased inspections or not. *THIS IS DESTINED TO HAPPEN AGAIN*

Call my concern overkill if you'd like but when the injuries are more severe, I'll say I told you so.

The only possible solution to this I see with keeping the cable system is to have the sled connect at the rear of the train, However this probably would create a totally different set of problems

Last edited by Charles Nungester, Thursday, April 29, 2010 8:04 AM
Thursday, April 29, 2010 8:27 AM

Thanks for the link, very informative!
I like pg 10 where it talks about how "rope" failures generally occur at sheaves, pulleys and winch drums. We all know that these rides have a lot of these components. I'm wondering if the cable gets to hot then wrapped around a drum of a rather small diameter, because it goes through a thermal cycle that it's shrinking on the drum then the cable is tightening up. So they use water to cool the cable to minimize this thermal event. Constant contraction/expansion of the cable all day long. This could potentially weaken the tensile strength over time.Water, heat, repetitive stress, and pulleys are all things that are apparently bad for cables. Overall bad design.

For the price of one of these rides and repeated stress of the launch system you would think that one of these EM inspection devices would come standard..

Compressed Air is the propulsion of the future!

Last edited by JoshuaTBell, Thursday, April 29, 2010 8:33 AM
Thursday, April 29, 2010 8:51 AM
Raven-Phile's avatar

Compressed air uses the same type of pulley/winch system, only the means of propulsion is different. The consequences of a pneumatic system's failure can be equally as devastating, if not more so. From what I recall, Ring Racer (the most recently constructed S&S air launch) has suffered not 1, but 2 catastrophic failures in it's relatively short life. The first was an air tank explosion, and the second was involving the cables.

I can't seem to locate the pictures of the cable mess, but it was exactly that.

R.I.P LeRoi Moore 9/7/61 - 8/19/2008
Thursday, April 29, 2010 9:17 AM

Thanks for pointing that out. I realized that after I said it....

Too bad gravity just doesn't cut it anymore...Or does it....

I believe compressed air is propulsion for the future of everything except roller coasters ;)

Last edited by JoshuaTBell, Thursday, April 29, 2010 9:36 AM
Thursday, April 29, 2010 11:25 AM
janfrederick's avatar

When we visited the Midway carrier museum in San Diego, we were told that the arresting cable was replaced after every 100 landings. Not really a fair comparison though because the cable is jerked and dragged all over a very rough surface with each arrest. I didn't catch how often the launch cable was replaced.

"I go out at 3 o' clock for a quart of milk and come home to my son treating his body like an amusement park!" - Estelle Costanza
Thursday, April 29, 2010 12:06 PM

As good luck would have it, I will be at Knott's on Monday. Was hoping it would open this weekend to allow the bugs to be worked out before I got there. Curious to see if the opening creates a bit of a mini local media circus.

Or is it already open? The date on the article is Monday, April 26. So what do they mean by "this Monday"?

Last edited by Shades, Thursday, April 29, 2010 12:09 PM
Thursday, April 29, 2010 12:34 PM

janfrederick said:
When we visited the Midway carrier museum in San Diego, we were told that the arresting cable was replaced after every 100 landings. Not really a fair comparison though because the cable is jerked and dragged all over a very rough surface with each arrest. I didn't catch how often the launch cable was replaced.

I doubt that the cable is wearing out due to rubbing on the deck (friction). I would bet it's stress/strain due to the shock load of catching a multi-ton jet. As someone (an air force pilot) explained to me, they land with engines at high thrust, so they can take off again if they don't catch the cable.

It would be interesting to see strain gauge or stress measurements on the two systems. The intamin system has a tensioning system, so the cable shouldn't go completely unloaded, I don't know if the tail hook does or not.

Either system is going to have the most broken wires where the rope passes over the sheaves and at the connection points when the load hits . With the plane, it's when the hook catches, with the Rocket, it's when the launch starts.

Thursday, April 29, 2010 12:39 PM

On another Intamin ride that uses wire rope, they used a multi-wrap winch drum. Think of the Warn winch on the front of a jeep. The problem was, sometimes the wraps would roll up on each other, and then drop back down. This tended to happen at the same point on the rope, and that was where the breaks tended to concentrate.

The solution to that problem was to go to a single wrap drum on subsequent rides. The park with the prototype gets to replace their rope at least once a year.


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