This video is brought to you by NordVPN.
Keep yourself protected online by going to NordVPN.com/ArtofEngineering to get 75% off
a 3-year plan.
Link below.
The Twilight Zone Tower of Terror at Disney’s Hollywood Studios is often regarded as the
best thrill ride to ever come out of Disney Imagineering.
The attraction seamlessly combines a 13-storey drop tower with immersive dark ride elements,
all tied together with detailed storytelling.
The ride was considered to be an engineering marvel when it opened in the summer of 1994,
and although it may not have some of the advanced technologies that are common on rides built
more recently, it is still an impressive achievement even by today’s standards.
The Tower of Terror was such a success for Disney that it was replicated on three separate
occasions, at California Adventure in 2004, Tokyo DisneySea in 2006, and Walt Disney Studios
Park in Paris in 2007.
The Tokyo version utilized a different theme and storyline compared to the other 3 towers,
and I personally find it to be the most aesthetically pleasing of the 4 attractions.
In 2017, the California version was re-themed to the Guardians of the Galaxy film series,
which included the addition of animatronics and large screens for the show scenes, however
the overall mechanics of the ride remained unchanged.
The first Tower of Terror in Orlando and the most recent installation at Disneyland Paris
both maintain the Twilight Zone theme which is based on the classic tv series that aired
from 1958 to 1964.
The four Tower of Terror attractions are all similar in concept, however the original Hollywood
Studios version features a unique ride system that is far more complex than the others,
and it offers an experience that can’t be found anywhere else.
The tower portion of the ride building is 60.7 m in height, and it houses two 48 m tall
elevator shafts where the drop sequences take place, along with a large mechanical room
above the shafts for the elevator motors.
The rear portion of the building is about half of the overall height at 32.0 m tall,
and it contains the dark ride component of the attraction along with the queue, load
and unload areas, maintenance and control rooms, and the gift shop.
There are 4 elevator shafts located at the back of the ride, and these connect to the
main drop shafts through horizontal passageways at the 1st and 5th show floors.
After guests go through the hotel lobby, library pre-show, and boiler room scene, they then
board one of the 4 rear elevators at the second floor.
At this point, it appears that the elevator car is the ride vehicle itself, but guests
are actually boarding a semi-autonomous vehicle that is positioned inside the elevator car.
The ride vehicles are loaded onto the elevators on the 1st floor below the passenger loading
area, and they are held in place by a locking mechanism on the floor of the elevator car
so they don’t shift as the elevator moves.
Once the passengers have boarded, the ride starts by lifting the elevator to the first
show scene.
For the two inner shafts, the show scene is located on the 3rd floor, and for the two
outer shafts, the scene is located on the 4th floor.
All four show scenes are identical, but they are offset like this to conserve floor space.
When the elevator doors open, the passengers see a long corridor where 5 hotel guests seemingly
appear out of thin air.
The figures then disappear in a burst of electricity as the hallway goes dark to reveal a single
window in a field of stars.
This scene is accomplished with two primary techniques that Disney uses quite often: forced
perspective and an optical illusion known as Pepper’s ghost.
The opening of the corridor is life-size, but the walls, floor, and ceiling all slope
inwards so that the height at the very end is only about 1.2 m.
This makes it appear much longer than it really is when viewed from the inside.
The wall at the end of the corridor is a rear-projection screen with a projector placed on the opposite
side.
At the beginning of the scene, a normal wall with a window is projected onto the screen,
but the wall fades out of the image as the lights go out to give the illusion of a window
floating in space.
At the front of the corridor just behind the first arch, there is a large pane of glass
oriented at a 45-degree angle that spans the entire width and height of the hallway.
This aligns with a second perpendicular hallway where another rear-projection screen is hidden
out of view.
The 5 hotel guests are projected onto this screen, and the image is reflected in the
pane of glass making them appear in the middle of the corridor.
This illusion is known as Pepper’s ghost, and it is the same effect that was famously
used for the ballroom scene in the Haunted Mansion.
After the ghostly figures disappear, the projection screen slides out of the hallway to reveal
fiber optic cables that are used to create the star field.
Many of the walls in the corridor are scrims made out of fabric, and fiber optic cables
are actually hidden all over the show scene behind the walls, as well as inside the elevator
car.
When the set goes dark, the light from the cables shines through the scrims, and the
cables in the perpendicular hallway are reflected in the glass to make the star field appear
three-dimensional.
After the corridor scene is complete, the elevator is then lifted to the 5th floor where
the ride vehicle exits into the 5th dimension show scene.
This scene features a number of visual effects, including a second star field that is achieved
by two large mirrors with fiber optic cables hidden behind them.
The mirrors are oriented at an angle to each other in a v-shape, and as the ride vehicle
approaches, they slide apart to allow it to pass through.
Although there are 4 loading elevators and 4 corridor show scenes in the ride building,
there are only two 5th dimension scenes on the 5th floor.
The four loading elevators are arranged in pairs, and each pair connects to one of the
main drop shafts through a single show scene.
The horizontal motion for this part of the ride uses a trackless system where the semi-autonomous
ride vehicles navigate across the 5th floor from one elevator shaft to the other.
The vehicles are known as wire-guided AGV’s, or automated guided vehicles, and they are
equipped with sensors that ride close to the floor surface.
There are wires installed in the floor that are used to transmit radio signals to the
vehicle, and the vehicle is programmed to follow the wires in a similar fashion to a
line-following robot.
The signals can also be used to control the speed, direction, and orientation of the ride
vehicle as it travels along the pre-determined path.
If the ride loses power and the radio signals are cut off, or if something falls onto the
floor and covers a wire, then the vehicle will come to a stop automatically.
The wire guidance system can be quite sensitive, and it is one of the primary causes of downtime
for the ride.
Once the ride vehicle exits the 5th dimension scene, it then boards an elevator car in the
drop shaft for the main drop sequence.
The elevator cars here are similar to the ones used in the 4 loading shafts, and they
also have a locking mechanism to secure the ride vehicles in place.
The ride has 4 pre-programmed drop sequences that it can execute, and the computer selects
one at random for each ride.
Each sequence consists of a number of varying drops and launches up the tower, with one
full drop from a height of 39.6 m, or about 13 storeys.
At the top of the ride, elevator doors on the front of the tower are opened, giving
guests a birds-eye view of Hollywood Studios.
The two drop shafts actually extend about 8 m above this point inside the tower, but
the top portion is not utilized during the drop sequences.
A certain distance is also required to safely bring the elevator car and ride vehicle to
a stop at the bottom of the tower, and so the maximum drop height that passengers experience
before braking is only about 27.4 m.
The ride system that is used for the drop sequences is based on the traditional traction
elevator, and it is not that different from an elevator that you might find in a normal
high-rise building.
The system was designed by the Otis Elevator Company, and it uses two giant induction motors
to accelerate riders up and down, reaching a maximum speed of about 63 km/h.
One motor is positioned above each elevator shaft in a mechanical room at the top of the
tower, and each one weighs nearly 60 metric tonnes and can generate 2,000 HP.
Each motor is connected to two cable drums in series, and there is 1 solenoid brake on
the end of each drum for a total of 4 brakes per elevator.
Two steel cables are wound onto the first drum, and these extend down through the floor
where they connect to the top of the elevator car, which travels along rails that are fixed
to the walls of the shaft.
A single cable is more than strong enough to support the full weight of a car along
with a fully loaded vehicle, but two cables are used for redundancy.
Two additional steel cables are wound onto the second drum in the opposite direction,
and they are attached to a counterweight that is used to offset the weight of the elevator
car.
The counterweight travels along its own set of rails inside the shaft, and it weighs about
as much as a single elevator car with an empty ride vehicle so that the motor only needs
to supply enough power to raise and lower the weight of the passengers.
Two more cables extend off the bottom of the counterweight, and they run around a compensation
pulley at the bottom of the shaft before connecting to the bottom of the elevator car.
This closed loop allows the motor to pull the elevator car downwards, resulting in acceleration
that is faster than a freefall.
When the motor spins in one direction, the car is pulled up from above, and when it spins
in the opposite direction, the car is pulled down from below.
The result is an intense experience unlike any other elevator where riders experience
complete weightlessness one moment and are pushed into their seats the next.
But just like any regular elevator, the Tower of Terror features a number of redundant safety
systems that keep guests safe.
First, there are the 4 solenoid brakes on the cable drums that are used to control the
speed of the elevator.
Each brake has 2 arms with friction pads that are clamped against the drum by a pre-loaded
spring.
There is a solenoid at the top of the brake, and when electricity flows through it, the
resulting electromagnetic force pushes a plunger outward which separates the pads from the
drum.
When the flow of electricity is cut off, the electromagnetic force is stopped, and the
spring pushes the pads back against the drum.
The friction between the drum and the pads slows the drum down and brings the elevator
car to a stop.
This design is fail-safe because the brakes are always active in their default state when
the solenoid is powered off, and they will stop the ride automatically in the event of
a power failure.
If the brakes were to fail, then a mechanical speed governing system on the elevator car
would activate emergency friction brakes that clamp onto the elevator guide rails.
There is a similar speed governing system on the counterweight as well, so both the
counterweight and the elevator car can be brought to a stop by the emergency brakes.
In the unlikely event that both steel cables supporting the elevator car were to snap,
this would also activate a set of emergency brakes to prevent the car from falling down
the shaft.
If all of these safety mechanisms were to fail simultaneously, which is extraordinarily
unlikely, then the falling elevator car would create a cushion of compressed air in the
bottom of the shaft which would help to slow the fall.
There are shock absorbers installed at the bottom of each shaft that would help to break
the fall as well, however these are not designed to catch an elevator car in a freefall.
Fortunately, this has never occurred on any of the Tower of Terror attractions, thanks
to an over-engineered design and redundant safety systems.
While we’re on the topic of safety, I want to take a moment to tell you about today’s
sponsor, NordVPN.
Just like thrill rides have layered safety systems to keep you protected at the theme
park, NordVPN gives you an extra layer of safety to keep you protected online.
When you connect to the internet with a VPN, all of your traffic passes through an encrypted
tunnel which prevents your internet service provider and other third parties from watching
and tracking your online activities.
NordVPN uses military grade encryption protocols with no data logging, so all of your personal
information stays private and secure.
If you’re not using a VPN, then you may be leaving yourself vulnerable to identity
theft and data loss, including stolen files, passwords, and banking information.
Of course, in addition to online protection, it can also be a useful tool for accessing
geo-restricted webpages simply by connecting to a server in another region.
There are thousands of servers available in over 60 countries, and it only takes a few
seconds to get connected.
Internet security is an issue that really needs to be taken seriously in today’s online
space, and I highly recommend that you keep yourself protected with NordVPN.
You can save 75% on a 3-year plan by going to NordVPN.com/ArtofEngineering, or by using
the link in the description.
That works out to less than $3 per month to keep all of your data safe, and for a limited
time, you can also use promo code ArtofEngineering to get an additional month for free.
I personally use NordVPN to keep myself protected online, and they really helped me out by sponsoring
this video, so please check them out by going to the link and consider signing up for a
3-year plan.
It helps to support me and this channel, but more importantly, it helps to keep you and
your data safe online.
Thanks for listening, and now let’s jump back into Tower of Terror.
After the ride has completed its drop sequence in the drop shaft, the elevator then moves
to the first floor where the ride vehicle reverses out of the elevator.
The vehicle moves backwards to the unloading area, and it rotates 90 degrees for the guests
to exit onto the unloading platform.
While the vehicle is in this position, an inductive charging system in the floor is
used to charge the onboard battery in the same way that you might charge a cell phone
on a wireless charging pad.
This is the only time during the entire ride cycle when the vehicle is stationary on the
ground, and so its also the only time when the battery can be charged.
The battery provides the vehicle with just enough power for its self-driving and communication
functions, and this is one of the reasons why there is no audio or lighting onboard
any of the ride vehicles.
Instead, all of the ride’s audio and lighting systems are located within the show scenes
and inside the elevator cars.
Once all of the guests have unloaded, the ride vehicle then moves to the rear of the
building where it boards one of the 2 loading elevators on its half of the ride, and it
is lifted up to the loading platform for the next group of passengers.
Since there are 2 loading elevators paired with each drop shaft, each half of the ride
can accommodate 4 ride vehicles operating at any given time: 1 at the loading platform,
1 in the show scenes, 1 in the drop shaft, and 1 at the unloading platform.
This means that a total of 8 vehicles can be cycling through the attraction at once,
giving a total ride capacity of nearly 2,000 guests per hour.
And since the two halves of the ride are independent from each other, one side can often operate
by itself when attendance is low or when the other side is down for maintenance.
This ride system makes the Tower of Terror very efficient, however Disney decided to
make changes to the design for the California, Tokyo, and Paris versions to increase the
capacity further and reduce downtime.
Since the wire-guided AGV’s were a common source of reliability issues, they eliminated
the need for self-driving vehicles by removing the 5th dimension scene and the 4 loading
elevators.
The corridor scenes that were previously attached to the loading elevators were moved over to
the drop shafts, and a second show scene was added at the 5th floor.
The scenes vary quite a bit between attractions, especially with the recent conversion of the
California tower to Mission: Breakout, however they all originally featured similar effects
like forced perspective and Pepper’s ghost, as well as other mirror tricks.
Since the new ride layout does not utilize AGV’s, the loading platforms had to be relocated
to the drop shafts, but here the ride vehicles are loaded and unloaded outside of the elevators.
Once passengers have boarded a vehicle, it is pushed into the elevator car by a mechanical
grab that travels along a track, and after the ride is finished, the grab pulls the vehicle
back out of the elevator for unloading.
A second loading area was also added one level below the first, which allows one vehicle
to be loaded while a second one is going through the ride cycle.
The elevator system itself is essentially identical to the original one used in Orlando,
but here it is used for the main drop sequence as well as moving between the show scenes.
Since each drop shaft can only accommodate 2 ride vehicles in this configuration, a third
shaft was added so that a total of 6 vehicles can cycle through the attraction at a time.
This greatly increased the overall capacity of the ride, and it also allows two shafts
to remain open when one is down for maintenance.
There’s no arguing that the second iteration of Disney’s Tower of Terror is a far more
optimized design compared to the original Hollywood Studios version, however it doesn’t
quite offer the same immersive experience that you can only find in Orlando.
While Tokyo may have the best aesthetics, and California may have the most engaging
storyline, there’s still something special about the journey through the Hollywood Tower
Hotel and crossing over into the 5th dimension that Imagineers simply haven’t been able
to reproduce.
Hey everyone, I hope you enjoyed today’s video about Disney’s Tower of Terror.
Let me know what your favourite Disney attraction is in the comments, and I’ll try to make
a future video about the engineering behind it.
Please subscribe if you want to see more content from this channel, and don’t forget to hit
the bell to get notified as soon as new video comes out.
Thanks for watching, and I’ll see you in the next one.