Roller coasters are complicated.
Usually, they have multiple trains flying through the circuit at once.
Though this is a simple concept to understand,
what keeps these trains from coming into contact with each other?
The more cars on the ride at one time, the more chance of them colliding, right?
Fortunately, roller coasters feature comprehensive systems to prevent this from happening in
the form of block sections, more commonly referred to as blocks.
But what are block sections, how can I spot them, and why does the roller coaster at my
favourite theme park need them?
In essence, blocks serve a single primary purpose; to allow multiple trains to navigate
the roller coasters layout at once.
This means, for example, that one train can be loaded with new guests, while another navigates the circuit.
As a result, the amount of riders that get to experience the attraction every hour increases!
But why do roller coasters need block sections to achieve this?
Can’t a train just be sent around the track if and when guests are secure and ready?
To the surprise of many, modern roller coaster trains don’t feature brakes on-board.
Instead, roller coaster designers have placed brakes at specific places around the track.
These brakes split the ride’s layout into discrete sections; block sections.
The computer system running the ride will only allow one train to be in each section
at once, preventing them from ever coming into contact with each other.
Simply put, If the block section ahead is occupied, the train will not progress from one section to the next.
But let's take a step back, where did the idea of blocks sections come from?
The concept originated in the mid-19th century, with the United States railroad system.
Unlike roller coasters, railroads require multiple trains to run at different points
along the track at once, all of which could move in either direction.
Various ideas were formed to help fix this problem, including strict timetables, specific
“train-orders” based on class, and finally the manual block system,
developed in 1963 on the Pennsylvania Railroad.
Through the use of signals, train operators were informed if there was a train within the section ahead or not.
These signals were changed manually, requiring constant communication between the trains
passing through and the block operator.
In the early days of roller coasters a very similar system was implemented.
Single, or several ride operators would keep track of all of the trains on the circuit,
stopping their trains if necessary.
This was either done through the use of a brake-man on the train,
or brakes located towards the ride’s station.
On roller coasters built during the late 19th and early 20th centuries, brake-men would
sit on each train, using a lever to maintain the correct speed throughout the circuit.
If required, they could also cause the train to stop.
This later evolved into an operator in the station, who would use a set of levers to
bring the train to a stop on the brake run, or allow it through to the station platform.
But as the railroads developed, so did roller coasters.
The manual block system was followed by the debut of an automatic version years later.
Electrical currents were used to keep track of the trains as they enter and leave blocks,
changing the signal box accordingly.
If a block was occupied, a red signal was shown, telling the next train driver to wait.
It wasn’t until 1959 when a similar system would be used on roller coasters.
Matterhorn Bobsleds at Disneyland in Anaheim became one of the world’s first rides to
use computerised blocks.
Sensors tracked the position of the various trains throughout the layout,
automatically stopping them if necessary.
While it was, and still is, critical for the ride operator to know the location of the
trains, the blocks were now controlled using a more responsive and accurate computerised system.
But how does it all actually work?
To an observer, the track is just one continuous circuit that the trains loop around.
But to the rides’ system, it’s completely different.
A computer sees the entire track layout broken up into a series of distinct sections,
known as block sections.
As we learnt earlier; only a single train is allowed within each one of these block
sections at any point in time.
But what defines the start and end of a section?
The answer, block brakes.
These brakes are present at the end of every block section and have the ability to stop the train completely.
For a train to progress from one block section to another, it must pass through a set of these brakes.
If the system senses a different train occupying the block section ahead, the block brakes
will cause the train to stop, preventing it from entering the next block section.
But these sections don’t have to be long stretches of normal roller coaster track followed by block brakes.
Any part of the ride that can stop and hold a train can count as a block section.
For example, a ride’s station is usually one block section, made entirely of block brakes.
Furthermore, a lift hill will also count as a block section as the train can be stopped
at any position during the climb.
With that being said, let's take a look at our example circuit.
First Train 1 leaves the station and begins to climb the lift hill, leaving the block
section within the station empty, allowing for train 2, in the block section behind,
to move forwards.
As train 1 leaves the top of the lift hill, it enters a new block section, and travels
freely towards the next block brake.
This allows train 2 to move onto the lift hill.
Once train 1 has completed the first half of its course, it passes through a block brake,
causing it to enter the next block section.
By doing this, the previous block section becomes empty,
allowing train 2 to navigate off the lift hill.
Train 1 reaches the end of the layout, passing through another block brake, and entering the station.
As a result, train 2 can pass into the empty block section ahead,
and complete the 2nd half of its course.
But let’s rewind.
What if train 1 didn’t make it through the entirety of section 2 - the train has gotten stuck.
As train 2 comes to the end of its block section, it passes into the block brake.
The computer system knows that train 1 is occupying the block section ahead, and so
engages the block brakes, stopping train 2.
If train 1 was to continue through the layout and move into its next block section, the
computer would sense the block section in front of train 2 is empty,
allowing for train 2 to move into it.
From this explanation we’ve actually learnt two additional concepts.
The first is that for a roller coaster to operate safely, there needs to be more block
sections than trains on the layout.
For example, a ride with three trains requires at least four block sections to work.
With four, one of the trains is free to move forwards into the empty block ahead.
If this ride only had three block sections all of the blocks would be occupied at once,
causing the system to hold the trains in their current position.
As seen within our example, block brakes can also be located part way through the main ride experience.
These are referred to as mid-course brake runs, due to their position.
Mid-course brake runs increase the number of block sections a ride has, and therefore
the number of trains that can be used at once.
Typically, these are found on rides with long durations, such as hyper coasters; or attractions
that feature a large number of smaller trains, such as spinning coasters.
Often, modern roller coasters feature roughly 2 block sections for every train.
The second concept we learnt was that if stopped, a train must be able to complete the remainder
of the layout from any given block brake.
As a result, block brakes placed during the ride are often raised high above the ground.
This means that if our train were to stop, it could slowly roll down the following drop
and continue the rest of the ride.
Roller coasters with launches instead of lift hills follow the exact same rules.
Rides with linear synchronous motors, LSMs, use magnets to propel guests along the tracks.
These magnets can also slow the trains down, effectively acting as a brake.
However, LSMs can’t stop the train completely.
To do this, most launched roller coasters will feature a block brake before the start of the launch.
Together, the block brake and magnet launch act as a single system.
If the block ahead isn’t clear, the train will roll through the block brake and launch
track, being slowed down in the process.
Most launch tracks are slightly inclined, meaning the train will slowly roll back towards
the block brake, where it is held.
Once the next block section is clear, the train will launch from a standstill
and complete the rest of the course.
But this isn’t always the case.
In the event that ride operators are unable to clear the next section,
riders might have to be removed from the attraction.
In most cases, each block brake is accessible via a catwalk and staircase, allowing for
ride associates to reach the train and perform a ride evacuation.
Since block brakes are designed to safely stop a train, they typically hold the entire
vehicle in an accessible position.
Here, guests will be taken off the ride with help from the operators, in a safe manner.
By utilising blocks correctly, roller coaster designers can help to maximise the amount
of guests that can ride the attraction every hour.
To do this, the timing and placement of the end of each block section needs to be carefully considered.
For example, if two individual trains are in adjacent block sections; train 1 should
progress through to the next section before train 2.
This prevents train 2 from stopping, allowing for guests to experience an uninterrupted ride.
As a result, block sections are a balancing act.
In normal operation, the trains shouldn’t stop at the end of each block section, but
instead move freely through it in one smooth motion.
Smart lift hills, which alter the speed of the chain, can be used to slow the train down
while the block ahead is waiting to be cleared.
In addition, rolling blocks are used to simultaneously let one train leave the station as another enters.
This synchronous movement of both trains effectively causes the same block section to be occupied at once.
Ultimately, block sections have always been a core element of roller coaster design.
Theme parks needed ways to increase the capacity of their rides by running as many individual
trains as possible, while ensuring the safety of its guests.
As roller coasters have evolved over time, so has their safety.
Through the use of block sections, a rides’ computer system can monitor the position of
each train, keeping them at safe distances from one another.
So next time you’re on a roller coaster observe it from the computers’ perspective,
can you spot the individual block sections at work?
Thank you for watching, and, we’ll see you all next time.