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justagrrl
09-12-2003, 09:14 AM
I was just reading Al's latest update. I was troubled by this:

"And when California Screamin' developed its usual problems on Sunday and had three separate break downs totaling over six hours of combined closure in one day, the DCA Guest Relations office was also hit with lots of attraction closure complaints."

It worries me to think that regular problems on a coaster like BTMRR might have led to an accident. Then I hear about regular problems on another Disney coaster and can't help but question safety.

With all the info about the cutbacks in maintenance, problems that shut down rides that are considered regular, the difficulty CM's have in just getting someone out there to take a look at problems, it's down right alarming.

No wonder numbers were down at Disneyland over the weekend.

merlinjones
09-12-2003, 09:19 AM
I don't go to DCA much, so I haven't noticed myself, but I often read complaints online about Screamin' going 101 a few times a day.

For those who track such things, what is the general cause of these shutdowns? Poor design issues?

Bruce Bergman
09-12-2003, 10:34 AM
Originally posted by merlinjones
I don't go to DCA much, so I haven't noticed myself, but I often read complaints online about Screamin' going 101 a few times a day.

For those who track such things, what is the general cause of these shutdowns? Poor design issues?

From what I understand, Screamin' has normal shutdowns at least once a day for something. You can't really call them hazardous conditions, just something odd happens and the overly-sensitive computer freaks out for your safety. :fez:

A lot of times all it is, the computer expects the train to get from Sensor A to Sensor B in 20 seconds. If it gets there in less than 15 seconds or longer than 30 seconds, the computer stops the ride.

And like the 'Block System' on a commercial railroad, with a Yellow light to show there is a train a few blocks away and a Red light to "Stop: the next block is occupied" there has to be a buffer of space between trains. An Emergency Stop braking and evacuation point on a coaster can only stop one train at a time, the first train has to get all the way through the block (plus a time cushion) before the next one can be allowed to enter it.

If one train is loaded very lightly and goes slower than expected, and the next is very heavy and goes faster than normal, the fast train could catch up. And if they called for an E-stop with both trains occupying the same block, the first train would get stopped by the brakes and the second train would crash into the back of the first. This would be bad, very very bad. :eek:

For lack of information otherwise, that is what stopped Big Thunder, not a ride operator watching a non-existant video monitor - the computer saw that the (derailed/crashed) train was overdue to clear the block and timed it out to trigger the E-stop, and/or that train didn't time out but another train was about to enter that block and the computer had to E-stop the trains to prevent a block intrusion.

The computers did exactly what they should have done, otherwise you would have had a second train crash into the first one stopped in the tunnel. And the resulting disaster of two trains crashing would have been much worse.

They could also trigger an E-stop if a block sensor is triggered and there isn't supposed to be a train in the area at the time. Supposedly, this happened several times at Big Thunder when all the wild ducks from the drained River moved in over the winter.

California Screamin' has some problems unique to the design, the main one being the Linear Induction Motors (LIM) used to propel the trains. The ones on the launch point overheat and can't get enough cooling from the water spray system between trains, especially if they are running all the trains.

The LIMs also have to be triggered by another computer in sequence as the cars go over them during launch (and another set of LIM's on the lift hill do the same thing, only slower), so if that control computer gets the hiccups the ride stops. And if the LIMs don't get the cars moving fast enough up the launch hill the ride E-stops to keep them from back-sliding uncontrolled.

--<< Bruce >>--

YellowMan
09-12-2003, 01:38 PM
^It's so good to see someone who knows what he's talking about. Everything you said seems like the logical explanation.

justagrrl
09-12-2003, 02:51 PM
Originally posted by Bruce Bergman

A lot of times all it is, the computer expects the train to get from Sensor A to Sensor B in 20 seconds. If it gets there in less than 15 seconds or longer than 30 seconds, the computer stops the ride.



That happens everyday? Up to 3 times a day?

Has it always been that way?

Bruce Bergman
09-12-2003, 05:18 PM
Originally posted by justagrrl
That happens everyday? Up to 3 times a day?

Has it always been that way?

They have had problems keeping it open and running all day without at least one glitch since California Screamin' was built and the park was opened. When they were still in the Test and Adjust phase they had some serious problems with the LIM's and some of the car sensor systems that had to be fixed, but since the park has opened and they worked the bugs out it is almost reliable. :rolleyes:

Nothing unsafe that I've seen, but your odds of the computers tripping an E-Stop of the ride for some odd glitch while you are riding are higher than the average ride.

I will gladly ride California Screamin', and I've never personally been E-stopped while riding it - but I also try to remember to be in a proper position (sitting upright, head forward, arms braced and at the ready) as I go through all the E-stop brake zones, so if the ride suddenly decides to E-stop I don't get slammed around. From what I've seen from standing there watching as the ride stops, those brake zones aren't gentle. It's like a panic stop in your car - they have 50 to 60 feet to get you stopped. :fez: (Imagine that the fez is a crash helmet...)

A big part of the heat problems with the "Launch Start" LIMs I mentioned earlier was they originally planned to supplement the cooling water spray with a few drenches from the wave machine under Paradise Pier between each train - but if they made a big enough wave to splash over the rocks and cool the LIM magnets, the waves also drenched all the people standing there to watch the launches. :eek: So much for that idea...

I have no access to insider information, I'm just an astute observer that also happens to fix stuff like that for a living. (Complex systems, but nowhere near that level of complexity.) :D

--<< Bruce >>--

gr8onesgir1
09-13-2003, 07:41 AM
Wow, Bruce from reading everything you said, it sure sounds like you work the ride. I won't agree with what you were saying but I can tell you that California Screamin, is totally a safe ride. If we notice anything on any of our trains, we do pull it off immediately. Oh the downtimes, good times.

efoxx
09-13-2003, 12:04 PM
as I recall they have had this problem for years over at SM as well. that is why cars are weighed before launch. excessivly over or under weight cars are actually pulled off the track. cars have something like 20 seconds per stop and MUST move on at the end or the ride will cascade. (I said all that as if the ride was still operating :crying: )

MonorailMan
09-13-2003, 12:24 PM
I've stopped on the CS main hill. The "WOW" factor got lost after about 10 minutes up there.... :D

DisneyFan25863
09-13-2003, 02:03 PM
I would be scared that you might fall back down the lift hill.....there isn't anything holding you except magnets, right?

tikiboy
09-13-2003, 03:04 PM
Does the Rock'n Roller Coaster break down as much as Screamin'?
I believe it uses induction motors also, and doesn't have the luxury of a water spray to cool it off.

Cadaverous Pallor
09-13-2003, 04:09 PM
What Bruce said is right on.

Superman, a ride at Six Flags Magic Mountain that also uses the LIM system, has always had lots of problems with breakdowns. I can't rightly say why. But suffice it to say that such a complex computer controlled system has a million diagnosic/sensor checks every time a car is prepped to go, and there are many reasons for problems (and phantom problems).


Originally posted by DisneyFan25863
I would be scared that you might fall back down the lift hill.....there isn't anything holding you except magnets, right? I'm 99% sure that both lift hills use the standard backward locks that prevent the train from going backwards on all lift hills. That's the repetitive "clickclick" noise you hear on all lift hills - the locks clanking into place as the train ratchets up the hill.

MonorailMan
09-13-2003, 04:19 PM
Originally posted by DisneyFan25863
I would be scared that you might fall back down the lift hill.....there isn't anything holding you except magnets, right?

How it works, is that all the cars are let's say positive. All the magnets are negative. Electrical charge must be sent through these magnets to make them positive, to propel the train. Therefore, if there's no power, the train is stuck to the magnets. ;)

lazyboy97O
09-13-2003, 05:32 PM
If Superman the Escape also has LIM problems then I doubt CS's LIM porblems are Disney's fault. This is probably a flaw with Intamin AG's LIM system.

Cadaverous Pallor
09-13-2003, 06:42 PM
Originally posted by lazyboy97O
If Superman the Escape also has LIM problems then I doubt CS's LIM porblems are Disney's fault. This is probably a flaw with Intamin AG's LIM system.

I would have to disagree.


Originally posted by Cadaverous Pallor just now
But suffice it to say that such a complex computer controlled system has a million diagnosic/sensor checks every time a car is prepped to go, and there are many reasons for problems (and phantom problems).
Also, please reread everything that Bruce just said about the ways computers prevent accidents.

CoasterMatt
09-13-2003, 06:49 PM
Actually, not to be a complete coaster geek on this,
but Rock N Roller Coaster at Disney-MGM doesn't use LIMS for launch, It uses a pusher car that is driven by LSMs. The car engages towards the rear of the train, then accelerates down it's own seperate little track. A magnetic brake system stops the pusher at the end, the it is sent back to launch position nearly as quickly as it goes out.

Superman the Escape at Six Flags Magic Mountain, also uses LSM technology, which is much more sensitive to timing issues than LIMs. With LSMs, the car itself contains rare earth magnets, and the stators have to turn off and on with remarkable precision. The stators in front of the vehicle pull on the vehicle, while the stators behind push; the inability to properly sequence this was the major reason S:tE opened to the public 9 months late.

California Screamin' is as safe as any other attraction built by Intamin AG, it is in Disney's hands as to whether or not it will stay that way. Disney made the design decision to not integrate better cooling into the launch system, and now everybody pays for it with increased downtime.

tikiboy
09-13-2003, 07:57 PM
Actually, not to be a complete coaster geek on this

Don't let that stop you from telling us all the good stuff! The fact that Rockn Roller coaster doesn't use the same launch system as Screamin' is very interesting.

Bruce Bergman
09-14-2003, 12:13 AM
Originally posted by MonorailMan
How it works, is that all the cars are let's say positive. All the magnets are negative. Electrical charge must be sent through these magnets to make them positive, to propel the train. Therefore, if there's no power, the train is stuck to the magnets. ;)

BZZZZZZT! Wrong! But thanks for playing! :p

The Linear Induction motor works just like an electric motor running a fan or pump at your house - the power pulses make strong magnetic fields in the stator magnets, which attract the rotor to make the motor rotate.

But unlike the regular induction motors at your house that use a fixed mains power frequency (60 Hz) and push the motor at a set nominal rotation speed (1800 RPM for a 4-pole or 3600 RPM 2-pole motor being the most common), the Linear Induction Motor has all those parts spread out in a row - the stator magnets are mounted stationary under the track, and the reactor plates under the car act as the motor's rotor, a magnetic steel surface (not permanent magnets) for the stator magnets to push against and move the train.

Since the coaster cars don't go by at a fixed speed (it picks up speed from a dead stop to terminal velocity) the magnets have to be fed AC modulated at the right frequency by huge transistors, and fired in time with sensors of the cars going by each set of magnets and picking up speed.

And since it wastes energy to energize magnets that the train cars aren't over yet or have already passed, the computer has to turn those magnets off.

If you run DC through the coils, you can slow down the train, but stopping the train from speed will take a bit more than that. Turning off the power means the motor has no effect on the train as it passes over.

Now that it's as clear as mud... :fez:

--<< Bruce >>--

MonorailMan
09-14-2003, 12:17 AM
"SORRY! NOT A WINNER!"

I don't know where my mind is. However, you are correct, and I look like a fool. Open mouth, insert foot. ;) :D :fez:

Bruce Bergman
09-14-2003, 12:23 AM
Originally posted by efoxx
as I recall they have had this problem for years over at SM as well. that is why cars are weighed before launch. excessivly over or under weight cars are actually pulled off the track. cars have something like 20 seconds per stop and MUST move on at the end or the ride will cascade. (I said all that as if the ride was still operating :crying: )

You know, I've never really studied California Screamin', but they could have a weigh track hidden there somewhere...

They have the weigh track at Space Mountain because there are no trim brakes, and the effect of gravity on the car speeds depends on the total weight of the car and passengers. A heavier car will go fast enough to catch up to a lightly loaded car and cause a block violation and an E-stop of the ride.

If you know you have a heavier car, you delay the launch an extra few seconds to leave an extra time buffer between trains. Some of my best SM rides were in overweight cars that they just held us for an extra 15 seconds before sending us out.

--<< Bruce >>--

Bruce Bergman
09-14-2003, 12:30 AM
Originally posted by MonorailMan
"SORRY! NOT A WINNER!"

I don't know where my mind is. However, you are correct, and I look like a fool. Open mouth, insert foot. ;) :D :fez:

S'Okay, everybody has to do that occasionally, just to remind us we aren't perfekt. :D At 01:30 Hours, after doing The Closing Number at Rod's and driving home, I'm surprised that came out as well as it did. I'm checking for stuff that must be answered and going to bed.

(Do we have an animated "nodding off" smiley available? Eyelids droop, fall asleep, and then startled awake again...)

--<< Bruce >>--

Doodle Duck
09-14-2003, 04:19 AM
Is it possible to STOP upsidedown in the loop on CS?

I've noticed this happening on other loopers.

If I'm in the train, just call the coroner.

Icy Bacon
09-14-2003, 02:11 PM
Is it possible to STOP upsidedown in the loop on CS?

I've noticed this happening on other loopers.

If I'm in the train, just call the coroner.As far as I know, that's happened twice. Once on Demon at Six Flags Great America, and once on the shuttle loop at Six Flags Belgium (just like Montezooma's Revenge at Knott's). Each time everyone survived, and in both accidents it was something breaking and stopping the train. It would be pretty tough for Screamin to stop in the loop...

As for the anti-rollback system on Cali Screamin, I'm pretty sure it works just like the brakes at the end do, and when the LIMs are on they stay off, but if there is no power they snap back in to stop the train.

Another interesting thing, is it looks like there is a single LIM at each end of each block in the main course... not sure if they actually do anything, or if the train just slowly coasts out of the block after a stop like on other coasters.

DL4EVER
09-14-2003, 04:57 PM
I'm 99% sure that both lift hills use the standard backward locks that prevent the train from going backwards on all lift hills. That's the repetitive "clickclick" noise you hear on all lift hills - the locks clanking into place as the train ratchets up the hill.

Except for Screamin' has no clickclick sound because the lift hill is NOT a chain lift.

CoasterMatt
09-14-2003, 06:34 PM
Originally posted by Icy Bacon
Another interesting thing, is it looks like there is a single LIM at each end of each block in the main course... not sure if they actually do anything, or if the train just slowly coasts out of the block after a stop like on other coasters.

Those act just like pinch motors, to help push the train out of the block