“Just to clear something up as there have been roughly a thousand misunderstanding's of how roller coasters actually work, and what went wrong.
Firstly we need to clear up that trains are not manually released by staff when they feel like, every roller coaster is controlled by a computer system that controls every action that happens, meaning that unless the ride's computer thinks that it's safe, it is impossible to release a train out of the station. Meaning that I could train a five year old how to operate a modern day attraction, like The Smiler, and he/she could do so safely with minimal knowledge
Next, I will define a 'block', a block is a piece of track that is designed to be independently completed from start to finish, and have a means of safely stopping a train at both the entry and exit of the block. In train logic, it is absolutely imperative that no more than one train occupies the same block at any time! This has been a fundament of roller coaster design since inception, and is the product of the well studied 'Absolute Block Signalling System' designed in the early 19th century.
The aforementioned computer is therefore responsible for controlling all of the block sections on the ride, and at no point should a train be allowed to enter a block if another train has not yet cleared it, regardless of the fitness of the ride.
Now that we understand the basic concept of how trains are allowed to travel around a track, let's get onto my theory of what went wrong, which are mainly based off of assumptions, which are based of my personal knowledge and experience.
The empty train most probably had an error message when it arrived into the station from its previous run, indicating something wrong with the train itself, the standard practice is to send the train around again, as most of the time it's an erroneous flag from a vibration or force sensor, which are calibrated have exceptionally low headroom for error. So the empty train was sent out to see if there was actually a problem, and if the message had've been persistent the train would've been removed. Unfortunately, for one reason or another the train failed to complete a full circuit, either due to an actual fault, as indicated by the sensor, or due to lack of momentum; as the train was empty. Either way the train cleared the first block; between the station and lift hill 1, cleared the lift hill, and entered the second block; between lift hill 1, and lift hill 2.
Now at the point the empty train cleared the lift hill, and entered block section 2, the ride's computer would've indicated to the operator that it is safe for the next train to depart. Seeing that there is no problem with this train, the operator proceeds as normal, dispatching the second train.
After this, what should've happened is that the computer should've indicated that for some reason train 1 is taking longer than usual to complete the second block, and then it would've realised very quickly that the train had stalled mid block.
At this point, the second train should've come to a halt on the lift hill, and not, for any reason have entered block 2. This didn't happen.
Instead, for some reason that I'm sure will be found, train 2 entered the block as normal, and we're all here now!
This logically is impossible, however one or more system must've failed, resulting in the accident, at no point is Alton Towers responsible for this, nor are any of the operating staff or engineers. The blame lies solely with Gerslauer GmbH, for their failure to properly test their software and electronics. My only major fear is how many other Gestlauer attractions have the same fault, which are just waiting for this to happen again!
My heart goes out to all of those involved, and I hope that you all get over this horrible freak accident with haste! Furthermore a big well done needs to go out to the Emergency Services, Alton Towers, Merlin, and all of the operations staff involved for having such a fantastic, efficient and relaxed response to this incident, I am very proud to have been a part of the magic!
The Smiler will not close, it may be closed for an indefinite period for the meantime, but it will reopen either later this season, or at the start of the next season. Sorry to those planning a trip to alton, but I wouldn't expect the smiler to be open for at least a month.
Lastly, do not fret, or become instantly terrified of roller coasters just because of this, though it won't help, you are 18 times more likely to be killed during a dance party than you are to be injured whilst enjoying a theme park attraction, more people die on the way to theme parks every year than have ever been killed in the entirety of the worlds theme parks, and lastly the chances of it happening twice are practically impossible, making The Smiler the safest roller coaster in the world!
So don't batten down the hatches, lock away your children, and cancel your tips. Instead #SMILEALWAYS”