Roller Coaster Safety: How to Manage Too Many Trains at Once
Articles, Blog

Roller Coaster Safety: How to Manage Too Many Trains at Once

September 22, 2019

I recently returned from a family trip to
Walt Disney World. Everyone in my family is a bit of a Disney
fanatic, and we’ve made many a trip. Yes it’s an expensive adventure, but it’s
a place that has a special place in my heart, and one that I truly believe has shaped me
into who I am today. Particularly my experiences at Epcot, perhaps
the only theme park dedicated to exploring new technologies and world cultures. What excites and interests me most about Walt
Disney World is their constant innovation and use of technology in novel ways. The technology throughout the resort has always
fascinated me. From what today we would call simple things
like using RFID tags to cue up narration segments on Living with the Land (Narration: Some
of our best ideas have been inspired by nature) not to mention Magic Bands, to the use of
Monorails as an actual transportation solution, oh and why not send it through the atrium
of a hotel and build a station while we’re at it, to the use of linear induction motors
to propel the ride vehicles of the Peoplemover (a system, by the way, which has been in near
constant use since all the way back in nineteen-seventy-freaking-five. (60Hz hum from propulsion system) Love that
sound! To the increasingly complex and impressive
Animatronic figures, with this new Na’Vi figure being remarkably fluid and believable. But this video isn’t about those things,
it’s about ride safety and capacity. Yeah. I’m a nerd. Deal with it. Because of Disney’s extensive use of theming,
they are able to hide certain ride control elements to make their attractions accommodate
more people while still remaining safe. What I’m talking about here are roller coasters. Roller coasters generally receive all the
energy they need at the beginning of the ride. Whether it’s a launch or a more traditional
lift hill, a roller coaster train starts the course with the maximum amount of energy at
the beginning, and then navigates the track with an overall downward slope from its highest
point. With rare exceptions, roller coaster trains
are entirely passive vehicles, requiring elements in the track to both provide them with energy
(such as a chain lift) and to stop or slow them through the use of brakes. Because the control elements are located in
the track, the capacity of a roller coaster is limited. When in operation, two trains cannot navigate
the course at the same time or a collision would be possible should one train encounter
a problem, such as a dislodged wheel, and come to an unexpected stop. In many roller coasters, this is managed with
large trains capable of handling many people. When one train is dispatched, another takes
its place in the station to be unloaded and reloaded. But that train cannot be dispatched until
the train in front of it returns to the station, at which point it is certain a collision cannot
occur as the first train has returned and is now stopped. This means that trains can only be dispatched
about as frequently as the ride is long. A roller coaster with a two minute ride time
can therefore only dispatch one train every two minutes, so its capacity is limited to
30 train loads per hour. This necessitates long trains with many seats,
or an acceptance of lower ride capacity. Now, if you’ve ever ridden Space Mountain,
you’ll know that each train holds a whopping 6 people. This is needed because the ride is enclosed
in a building and doesn’t have a lot of space. Which is odd given the name. Anyway, the tiny trains are able to navigate
really tight corners and sudden changes of direction, which allows for the ride to be
very thrilling even though it’s so compact. But with only six people per train, the ride’s
capacity would be pretty awful if only one train was allowed on the course at once. With a ride time of 2 and a half minutes,
only 144 people could ride per hour. So, there must be some tricks up their sleeves. The first and most obvious trick is that there
are two mirrored copies of the same roller coaster inside the mountain at Walt Disney
World. So now we’ve got 288 people per hour. Whoop-a-de-freaking doo-da. But if you pay attention while in line, you’ll
see that they send a train about every 20 seconds. With two sides running, that’s like sending
6 people every 10 seconds. That’s a much more impressive 2,160 people
per hour. But how can they do that and still be safe? Dispatching a train that frequently means
there are about 7 trains running about at once. Well, the fact that the ride is in nearly
complete darkness means that Disney can hide a lot of safety elements. What are they hiding? Lots and lots of brake runs. Incidentally, it’s not that hard to see
what Space Mountain looks like with the lights on, just ride the peoplemover while it’s
broken down and you’ll get a good view. There’s oodles of mechanical equipment everywhere,
and among the wires, girders, and gobbledygook are frequent, regular intervals of straight
ride track containing brakes just like you see in the station, but stronger. These are called brake runs, and they are
capable of bringing the train to a complete stop with a moment’s notice. Let’s build a mini-roller coaster using
marbleworks. Yes, marbleworks. When a marble is placed on the course, it
can’t be stopped until it reaches the bottom. If these marbles were vehicles containing
fragile and litigious human beings, the only way to prevent collisions would be to only
allow only one marble on the track at once. But let’s imagine that at each connection
to the next piece there is a brake run that can stop the marble. Now we can send more than one marble at a
time because there are multiple places that we can stop them if necessary. To prevent collisions in a rollercoaster,
the ride’s computer system is constantly monitoring sensors in each of these brake
runs which tell it if a train is there and how fast it is going. The computer’s goal is to ensure there is
always a brake run between trains. It will not allow a train to pass through
a brake run unless the following brake run has already had a train go through it and
is now clear. If the train in front of you hasn’t made
it out of its own brake run, the computer will immediately apply the brakes ahead of
you to stop your train and prevent a possible collision. These intervals on the track are called block
sections, as any Roller Coaster Tycoon aficionado would know. Also of note is that the type of brakes used
in roller coasters generally require power, often in the form of air pressure, in order
to be released, with a spring providing the actual braking force. A sudden loss of pressure will cause them
to immediately engage. Now, with trains being sent every 20 seconds
in Space Mountain, there needs to be a brake run at least that frequently throughout the
ride. But sticking to that interval for brake runs
would require that each train go through the course at precisely the same speed. If the train in front of you were to slow
down even just a little bit, your train would need to be stopped at the next brake run to
eliminate the risk of a crash. This would happen because the computer didn’t
see the lead train go through the brake run and can’t be sure a collusion won’t happen. This would also require all trains behind
you to be stopped. Additionally, if your train got ahead of where
it should be, there would be no way to prevent a collision with the next train should it
stop unexpectedly. There should therefore be a brake run about
twice as often as the trains are dispatched. This allows wiggle room for inconsistent train
speed, and ensures there is always at least one brake run between every train. And in fact, if you pay attention while riding
Space Mountain, you’ll notice an odd regularity in the ride. Space Mountain as a ride is very twisty, turny,
droppy, and fun. Kinda like marbleworks. But about every ten seconds, you spend a moment
going perfectly straight. Then you resume the shenanigans, and after
another 10 seconds, you go perfectly straight for a brief moment. After which point you again spend roughly
10 seconds careening through the galaxy, before going perfectly straight. Each of these straight sections is a brake
run. Brake runs have to be straight as the brake
fins below the train need to be lined up between the squeezy bits here. And though you can’t see it, there’s also
a platform and walkway beside you along the brake run in case of a ride evacuation. With frequent brake runs, the computer controlling
the ride can also adjust the speed of trains. Because train detection sensors can determine
the speed of each train in addition to simple presence, the computer can compensate for
a train going too fast by lightly applying the brakes to slow it down. In this case, the brakes would be referred
to as trim brakes, and you might notice your train being slowed down in these straight
sections from time to time. Likewise, it can slow trains if a train up
ahead is going slower than usual. The brakes and computer system work together
to allow perhaps as many as 7 trains on each track to traverse the course at once. But sometimes errors do occur. If the computer tries to slow down a train
and slows it too much, it may not clear the following brake run before the train behind
it catches up. Or perhaps the brakes failed to act well enough,
allowing the train to get too close to the following train. Or even simpler, a sensor may be acting up
and reports something weird to the computer, making it think a ride vehicle is present
when it actually isn’t. In these cases, the computer will need to
take over. Though I can’t confirm it as I’ve never
worked on a roller coaster or studied its operating minutia, it’s likely any of these
scenarios will trigger a complete stop of the ride, with every brake run instantly engaging
to stop all motion on the track as soon as possible. This safety measure is probably the cause
of many a lengthy breakdown, as the ride will have to be manually reset after these emergency
stops. In fact, there’s a great video here on YouTube
of the Disneyland space mountain, that’s Disneyland in California, going through just
that. Disneyland’s space mountain is slightly
different in that there’s a single track with each train holding 12 people. In the video, you can see that there are trains
scattered throughout the mountain, with each of those brake runs holding a train. The cast members then go backwards through
the mountain, starting at the bottom, releasing trains one at a time through the rest of the
ride. Once all the trains have returned, they can
begin the process of restarting the ride. The unfortunate thing about Space Mountain
is that’s it’s pretty much impossible to show you any of this. Disney went the easy route and relied on the
cover of darkness to hide what’s going on. But at Big Thunder Mountain Railroad, I can. Remember how I said “Because of Disney’s
extensive use of theming, they are able to hide certain ride control elements to make
their attractions accommodate more people while still remaining safe” earlier in the
video? Well, at this attraction, they use a different
method. Big Thunder has an immense capacity, with
each train consisting of 15 rows that can accommodate two adults with a child. AND, Big Thunder’s station uses two loading
platforms with track switches, which allows for sending trains twice as fast as they can
be loaded. Sending trains so frequently means that multiple
trains occupy the track at once, which requires the use of block sections to prevent collisions. But rather than use frequent brake runs which
are obvious without Space Mountain’s shotgun approach of complete darkness, Big Thunder
Mountain Railroad contains three separate lift hills. A lift hill can be a type of block section
as the train can be stopped simply by stopping the lift. Lift hills also offer more flexibility, because
the train travels along it for a large number of seconds and therefore is in complete computer
control for longer. The computer has all this time to decide if
it needs to stop the train, allowing for a large amount of slop and inconsistency between
trains. Also, because each lift hill moves the train
as part of its normal operation, the ride can recover from minor trouble by restarting
a train’s movement after a stop was required, so long as it’s safe to do so. This is in contrast to Space Mountain, where
the block brakes are simply providing a last-minute means of stopping the ride altogether in emergencies. This merging of theming and mechanics is one
of those things that I consider genius on Disney’s part. The extra lift hills on Big Thunder seem,
from the rider’s perspective, to simply be theming elements or perhaps just a fun
addition to the ride, but they are more than that. They are an integral part of the ride’s
safety systems, allowing for a huge boost in ride capacity all the while protecting
you from injury (and the company from lawsuits). Expedition Everest at Animal Kingdom takes
this one step further. I don’t have footage of the ride so I’ll
be brief, but this ride contains two lift hills, and two reversing sections. All of these elements allow the train to be
stopped if need be, with the reversing sections stopping the train as part of a normal ride
experience. By building a stop into the ride’s theme,
there is yet another added point of flexibility. In this case, if a train in front of you is
occupying the next block section, the ride system simply holds your train longer than
usual. Once it’s clear to go, the train is released. If you’d like to see this ride in action,
check out the link below or through the card on your screen. And please, fix the Yeti. I’ve often felt that Disney has shaped the
kind of person I am in more ways than one. I’d say a large part of my interest in technology
comes from this technological mecca of entertainment. It was always fun to try and figure out how
they did what they did, and let me tell you, I’m still having fun doing that today. Thanks for watching, I hope you enjoyed the
video! And if you did, please consider subscribing. I’d also like to thank all of my supporters
on Patreon. You can also support this channel through
a totally voluntary contribution by visiting the link below or on your screen. Your support can help me make videos like
this more frequently, and your consideration is much appreciated. I’ll see you next time.


  • Reply Diaval June 26, 2019 at 1:49 am

    Yes, Please. Fix the Yeti!

  • Reply casanova419 June 26, 2019 at 2:00 am

    How can you tell who is a nerd? By the loud shirts they wear.

  • Reply Yuri Sá June 26, 2019 at 10:17 pm

    Disney’s technological Mecca… ok, no more YouTube tonight

  • Reply Dana Danarosana June 27, 2019 at 7:22 am

    I remember on a trip to Disneyland (CA) when I was a little kid, we rode the Matterhorn. When we were released, the attendant said there were a couple bobsleds stuck in there… and "this one should break them loose"… Years later I realized he was kidding… but a little scary when I was 6!

  • Reply Jason June 27, 2019 at 10:52 am

    The shape you are today is because of too many Mickey Mouse pancakes

  • Reply SandpiperN121PP June 27, 2019 at 8:18 pm

    I got to go on Space Mountain with the lights on and it was fantastic! It looks so cool inside!

  • Reply Fred Stiening June 28, 2019 at 8:23 am

    Another consideration is that each stopping point, the train must be able to return using only the potential energy from the elevation, not the kinetic energy, since it is starting from a dead stop. This means on an inverted loop, it needs to build up enough speed to have enough momentum to complete the loop or a mid track lift hill to add back more potential energy. Friction will also vary by temperature, and if the ride is outdoors, wind and humidity in the air – so it needs a lot of safety buffer

  • Reply Jay Brooks June 29, 2019 at 11:00 am

    6 per train?!? It’s 12 side by side with a lap bar I thought?!? Or was it 24?… I remember the trains being longer than 2 units.

  • Reply BMO22 Filmmaker June 29, 2019 at 9:02 pm

    OMG I've been looking for a vid like this for a loong tiime 🙂 this is the nerdy content i neeedd

  • Reply Haunter Mansion July 1, 2019 at 8:50 pm

    I remember timing Rocket Trains at SM while opening the ride. As you alluded to after an Emergency Stop and during the reset having to manually release the trains from the unload area back up the track to the Main Lift. I recall this occurring one night and the Lead in charge (since we are at WDW let’s just call him Mickey) first removed all of the guest and then starting at Brake 10 started releasing trains. The trains were stopped at 10, 8, 6, and so on. After Mickey released 10, they then proceeded to 6 (Brake 8 is in the RED Re-Entry Tunnel and only visible if you look inside) and yes, a HUGE crash inside the tunnel when train at 6 met train stopped and forgotten about in Brake 8. This and many more Interesting Stories locked inside my Mouse Brain.

  • Reply Amaury Garcia-Cumming July 2, 2019 at 6:08 am

    You should do this for Incredicoaster, formerly California Screamin'.

  • Reply joe suwalski July 3, 2019 at 8:56 am

    Epcot isn't my favorite park but I always spend the most money there LOL.

  • Reply Brian Driscoll July 3, 2019 at 3:29 pm

    Maximum amount of potential energy

  • Reply MrAwesomedude808 July 3, 2019 at 7:06 pm

    Doesn’t Peoplemover actually use LSM rather than LIM?

  • Reply Brian Sevintin July 5, 2019 at 11:35 am

    What excites me is the evil scary things they do to people to fool. The amount of descusting sexual things they hide yet show in plain site. The mysterious 33 stuff and his not spoken about but spoken a lot about inapropiate interest in small children. Brainwash scary institute.

  • Reply iron 13 July 5, 2019 at 7:13 pm

    I feel like the tech behind the Disney Attractions is enough to make an Epcot attraction out of

  • Reply AeonAxis July 6, 2019 at 5:12 pm


  • Reply -.- Cat July 7, 2019 at 7:16 am

    As a human being i attest that i am indeed fragile and letigious

  • Reply Jordan Miles July 9, 2019 at 12:41 am

    Just wanna chime in on Expedition Everest, at the reverse point with the yeti footage I’ve had my car sit there for about a minute, so can confirm it’s a control point.

  • Reply DudeBro Chill July 10, 2019 at 7:40 am

    Have you not ever heard of block sections? Lol you can absolutely run more than one train on a coaster track… every theme park win roller coasters every single day.

  • Reply DadGeek UK July 10, 2019 at 10:20 am

    For how 'not' to manage too many trains, Google "Alton Towers Smiler Ride Crash".

  • Reply K Lamb July 12, 2019 at 7:32 pm

    It’s hard to stay engaged with a video when when the person talking about the topic doesn’t seem engaged or excited. And as far as the “yeah i’m a nerd” comment: I clicked on this video to learn facts about train management. I’m fully aware that you’re a nerd and I’m fully aware that I’m a nerd. Breaking the flow of information to dryly draw attention to it isn’t clever or funny it’s distracting just hit me with the train facts

  • Reply macronencer July 13, 2019 at 6:58 pm

    I LOVE rollercoasters! I used to be a paid-up member of two coaster clubs, I've done charity marathon rides, and I was even on the naked Nemesis ride at Alton Towers (which was an absolute hoot). I love this video! Excellent explanations of blocking and trim. I rode Expedition Everest in 2007, and I brought a souvenir woollen hat back to the UK. It's still my favourite winter hat. Happy times 🙂
    Dammit, you've made me want to start riding again…

  • Reply hugtrain July 14, 2019 at 2:50 pm

    hello my fellow saftey nerd

  • Reply TheJakeman789 July 17, 2019 at 5:00 am

    Honest question. Is this guy gay?

  • Reply Cody Brumbaugh July 20, 2019 at 2:33 am

    I do work and operate roller coasters. You are correct if the computer since an error it’s stops everything immediately locks up all brake stops any chain left what Have you. And in that case unless the issue can be corrected by maintenance and that the guest can safely be transport on the ride then there will be an evacuation. And a lot of times the rides being stuck is not the ride being broken but simply an error to ensure the safety of the guests.

  • Reply Toasty Volvo July 21, 2019 at 2:09 am

    don’t raise your hands on Space Mountain. I almost got mine severed.

  • Reply Ian Lehman July 26, 2019 at 11:57 pm

    I don't know if anyone recalls, but at king's dominion, there's a coaster named "ricochet" that works with multiple small trains running at a time, and multiple brake runs, along with all the computerized control equipment, which was all on the ground below the very elevated and compact circuit, as to accommodate said equipment.

    This ride is/was Infamous for working poorly, even less reliable than Volcano. It was such a short track that the ride was never synchronized between the number of trains and their speed. (This lack of synchronization was likely made worse by poor ride attendance. Also, Trains were very small, single-car 4-person, IIRC) Often, a train would return too early for another to leave the station to allow for the offloading of passengers. This could have been ENTIRELY prevented by removing a number of trains from the ride, as there were more than twice as many would usually be needed. Instead, it was decided for the rollercoaster to run constantly regardless of attendance, and if any immediate issue or hazard arose, all brake runs would be engaged, Stopping the ride until the issue could be resolved. Remember how I mentioned the entire ride was elevated to accommodate the control systems? Because of this elevation, ride evacuation was impractical, and instead of evacuating passengers to allow them to go somewhere else, the passengers would have to wait until the computers could be persuaded that it was safe to release the brakes.

    Even if this wasn't an issue, but especially because it was, the Peanuts rollercoaster was far more fun, as that one was smoother, had more comfortable turns, and better acceleration, and far better elevation changes, along with some entertaining track features (needless to say, it also took up less space). The only feature the Ricochet boasted was uncomfortably tight, consecutive lateral switchbacks between brake runs. I rode the Peanuts rollercoaster three times and never tried of it, despite its rather simple course.

    Moral of the story: A ride can only be as fun as it is safe/reliable.

  • Reply nachosNapples July 27, 2019 at 1:37 am

    Avatar was a disney movie?

  • Reply Wallywutsizface July 29, 2019 at 12:52 pm

    Huh, I’ve always wondered why the stopping section of Everest seemed to vary in the way of time stopped. Thanks!

  • Reply Dennis McIntyre July 30, 2019 at 7:59 am

    Brake runs are found on most roller coasters these days. These can be used to fine tune the roller coaster's speed in response to rider feedback and testing. If a certain section of the track is too rough or subject to too many g's, the computer can be programmed to reduce the speed to compensate for it.

  • Reply Noah Beeri July 30, 2019 at 4:12 pm

    Good video, nothing technical I would disagree with, but you made it sound a little bit like it's Disney alone who does it and invented, while it's just industry standard and can be found in pretty much any theme park.
    Next to lift hills, launches are also a way to separate blocks, as it can be seen on Taron for example.

  • Reply Arthur Feitosa July 31, 2019 at 8:57 pm

    Once Walt Disney was for the middle class, today you gotta take a new mortgage in your home to take the wife and kids there.

  • Reply Reverand ZomBre August 9, 2019 at 5:29 pm

    this was so interesting! thanks!

  • Reply Trial N' ERROR August 10, 2019 at 6:54 pm

    I feel the exact same way. I was just as amazed as every other kid was at Disney, but I was amazed at the how and not the wow of what I was looking at.

  • Reply Genshi Media Group August 12, 2019 at 6:53 am

    Very informative video, thanks for that!

  • Reply Jasmine Johnston August 14, 2019 at 3:31 am

    Not all roller coasters use chain lifts. A lot of modern ones use launches instead. There are many ways to launch a roller coaster train up the hill at high speed. There’s the hydraulic launch, which uses a catch car attached to a hydraulic winch that shoots the train up the hill, and there’s also LSMs (linear synchronous motors), which use a magnetic propulsion system like the People Mover uses, only it makes the ride faster

  • Reply Andrew Hill August 14, 2019 at 1:05 pm

    More Disney videos please

  • Reply Buff Barnaby August 15, 2019 at 9:53 am

    can you force them to open WallyWorld ?….I drove my family a long ways and they are down for repairs.

  • Reply Nik August 19, 2019 at 4:13 pm

    Disney World seems so cool. It's my dream destination but completely out of reach for now. Hopefully some day!

  • Reply Arius Da Cat August 21, 2019 at 2:58 am

    This is amazingly fascinating, thank you for going so in depth! I have never been to WDW but frequent Disneyland, if only they would replace the Space Mountains trains with those at WDW it would be much more comfortable.

    Keep up the amazing work!

  • Reply THE DESTRUCTION CHANNEL August 25, 2019 at 10:01 pm

    Thunder mountain is the best!!

  • Reply SkyWolfAlpha August 28, 2019 at 8:11 am

    thank you for pointing out the monorail. I would have missed it otherwise.

  • Reply merriettagirl August 28, 2019 at 10:42 pm

    Another thing, on large coasters with long lift hills, one super safe place to stop a train, unfortunately for riders that might later need to be evacuated, is at the TOP of the lift hill…That's just in case every frikkin set of brakes on the whole ride fails, and the second train slips through the holding brakes AND station brakes, there's a good chance that gravity will still prevent a collision since that train probably can't make it up the stopped lift hill far enough to hit the train at the top. Ok that's my 2 cents. Sorry people at the top, you gotta walk down now.

  • Reply radudeATL August 30, 2019 at 3:44 am

    You are hella cool, man.

  • Reply kittiekat1236 August 30, 2019 at 10:02 am

    Actually hats falling off onto the tracks was usually the reason for a 101

  • Reply James Read August 30, 2019 at 10:21 pm

    This is precisely what Alton towers didnt do in the smiler incident, they accidentally forgot there was a train stopped in one of the blocks, and sent another one, filled with passengers

  • Reply Victor Mandala September 3, 2019 at 5:59 pm

    This video definitely helped led me into the career I’m pursuing. Disney Imagineering or working for some other company designing control systems for amusement rides

  • Reply Teen Conservative September 5, 2019 at 2:51 am

    I love your videos on old tech and power outlets… but when you start talking Disney you’re talking my language! Keep making some Disney videos here and there!

  • Reply Teen Conservative September 5, 2019 at 3:00 am

    FIX THE YETI!! Joe Rhode

  • Reply ISSAI HERNANDEZ September 5, 2019 at 9:58 pm

    1:47 is my local Six Flags

  • Reply Kevin September 16, 2019 at 8:45 pm

    The Bostom MBTA could learn a thing or two from this lol.

  • Reply Gabe Riggs September 18, 2019 at 6:28 pm

    You forgot to talk about the elevator lift. Also, a launch can be used as a "brake run."

  • Reply dish soap September 20, 2019 at 1:03 am

    A few days ago my train on everest stopped on the lift hill

  • Reply Reeta Tassberg September 20, 2019 at 9:23 am

    5:08 this system is used in europe in subway cars

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