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.
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