I get that they have connections that keep them on the track. I’m talking about insane ones that aren’t always consistent, like the Top Thrill Dragster or Kingda Ka. These huge roller coasters have very minimal instances of accidents, yet aren’t even consistent at getting over the apex (instances of rollback and having to try again). So my question is how are these made to be reliable and how are they maintained even when in use a lot?
In: Engineering
Coasters, like all amusement park rides, are maintained at night when the park is empty. There are rigorous inspection and preventative maintenance procedures, performed by mechanics that have been trained to work on the specifics of the attraction/coaster.
There are redundant systems for anything that could be a risk to people Or equipment. For example, the wheels that ride on the track are redundant such that a certain number can fail without endangering the occupants or bystanders.
Static structures like the track are designed with insane factors of safety such that the steel is very conservatively loaded relative to what the steel can handle.
Coasters, like all rides, have tracks divided into zones such that only one coaster train can be in a zone at a time. In the event of a rollback, brake failure, etc., there is no way for two coaster trains to collide with each other.
Ride control systems are also redundant, and designed to fail safe (much light stoplights at road intersections are designed to fail in a safe state).
Source: used to work on theme park ride design teams
The big risks on a rollercoaster aren’t in the lifts, but rather in the turns. By now, rollercoaster carts are very easy to keep on the track. Even if those safeguards like you mentioned get activated, the carts will stay on the track. The much, much bigger risk is G force on the turns. However, these can be calculated by using some basic physics, and the specs really don’t change much as they age. Lastly, rollercoasters are maintained after hours, as well as during the offseasons.
In my younger years, I worked in a theme park on multiple coasters.
To put it as ELI5 as possible, big coasters use computers to detect where a car is and brakes to stop them. Just like trains, they use a block system to identify parts of the track a train is and stop another train entering that section. That’s why on some coasters you might suddenly hit a straight bit of track and slow s little bit. These are called “trim brakes”. If a car is in the section ahead you’ll come to a complete stop, otherwise you’ll slow a tiny bit and continue. The lift hill is also used as a block section, so you might stop right at the top of the hill for a short while. It’s not broken, it just means it’s not clear to be able to run the section amd come to a safe stop before encountering another car.
Coasters used to use physical clamping brakes, but now use magnetic braking more often. Ones like you mentioned, the launch coasters like Top Thrill Dragster, will launch, then immediately behind metal fins will pop up. These are part of the magnetic brakes, so if it rolls back, they will slow it down before returning in to the station. Do a YT search for launch coaster launch and you’ll see these fins pop up behind the car.
Even more modern coasters use LIM or Linear Induction Motors. They are permanently up and can be used to propel or brake a car.
These are white fins in the middle of the track. If you look at a POV of Tautatis coaster, there’s a part where it uses LIM to increase its speed over multiple passes after a track switch. If the switch failed, these same fins would be able to stop it. Otherwise the same fins propel it too speed it can make it over the hill on its second pass.
Top thrill dragster and kinda ka are prone to rollbacks because they only want to apply enough force to the train to *just barely* make it over the top. How much force that needs depends a lot on not only the weight of the passengers but also the weather. The ride’s computer calculates how much force is needed based on the last 3 launches.
You may notice that rollbacks often happen early morning, or after it’s been down for a while. And that’s because the weather can change quite a bit from the last time the ride launched, so using data from the last 3 launches is often either underpowered or overpowered. Rollbacks during normal operation are pretty damn rare.
For those of you who are unfamiliar, a block zone is a section of ride that only one train may occupy. At the end of a block zone is a method to stop a train in case the block zone ahead is still occupied. This is the safety system that prevents roller coaster trains from colliding with one another.
One of the main reasons roller coasters have great track records is because there are really only a few companies that build them. If more random or inexperienced companies were building coasters you’d see way more problems. The companies that do make these rides have to think of every problem and they work to address any problems the ride will or could have. Everything about the ride is mostly redundant which just adds to the saftey.
TTD and Kingda Ka experience rollbacks usually from undetectable or unforeseen circumstances. Differences in wind or train weight (depending on how full it it is). The ride is designed to rollback if needed and you can see magnetic break fins rise up after the launch. After the train rolls back, the rides computer system will tell the hydraulic motors to launch the train faster and it will (usually) clear it after the second attempt.
Now onto reliability. Rides are expected for HOURS every morning prior to opening. Mechanics will inspect the ride and replace and or fix the ride if needed.
That’s more of the structural side now onto the safety systems. Every roller coaster has block sections which divides the rides layout into different sections. Before a train can enter another block zone there must be a way for the ride to come to a complete stop and continue again. Each block zone can be occupied by one train, the computer will automatically stop a train if it detects another train in the following block zone.For most rides the block zones will consist of a lift hill, the main course and the section of brakes at the end. Many rides also have break runs midway through the ride that allow more block zones and more trains which makes the lime move faster. These block zones are tested every single morning to make sure they work and if they for some reason don’t the ride doesn’t open.
The rides restraints also have alot with them. Almost every coaster restraint has 2 locking mechanisms. If it’s a ratchet and pin system there will be 2 pins locking the restraint in its place. If the restraint is hydraulic then there will be 2 hydraulic cylinders per restraint. TLDR; if one part of the restraint fails another part will act as a fail safe. Coasters also have ALOT of wheels and you’d need around 8 wheels to completely fail for a ride to derail.
Probably the main thing that keeps them safe is the fact parks don’t take risks. If the ride computer detects a tiny fault or error the ride will completely shut down and the ride operator cannot override it and maintenance personal with have fix it. Airplanes operate in a very similar way with being constantly inspected and minimizing risk whenever possible. There are also plenty of strict laws that coaster manufacturers and parks need to abide to. After every accident, state inspections take place and whatever the cause is will make parks be way more careful in certain situations.
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