First post, though a regular reader, but I'll come to that in a minute.
Firstly I want to say that I hope everyone involved recovers as quickly, and fully as is possible.
Secondly, I am a little embarrassed that something like this has finally led me to sign up, but I want to to raise something that after 13 pages hasn't been suggested yet.
Does this not look very similar to the Alton Mouse incident to anyone else? I'm not suggesting that there are no other possibilities, but it is most likely that an override of the block system one way or another has caused this accident (along with other contributing factors.)
Those that don't understand how this can happen only need to look to the Alton Mouse accident in the early 90's. A car valleyed, the operator restarted the system, thinking that the valleyed car would also restart (I know right?) the system lost the valleyed car and this allowed 2 cars to collide in the same block. The operator was found to have keys that they shouldn't have had, which allowed for the system reset.
Obviously, if an override of the block system of some sort is the cause, then the circumstances will be slightly different. For one thing, as mentioned above, I highly doubt a modern rollercoaster would run on auto, like the Alton Mouse did, without all cars accounted for (unless the system is told there are less cars than is actually so.) But there are still ways to override the block system, and I am confident that, one way or another, this will have been a factor.
If you look at past collisions on rollercoasters, this is very often a factor, so it's also the obvious answer.
The most important question is, if this does prove to be the case, how do they reduce the chances of this happening? Especially as this would by no means be the first time it has happened. And is a possibility on any rollercoaster.
IMO the technology exists to display to the op, and tech, exactly where every train is on the track, down to the MM, so I am surprised this is not utilised already. Blocks, work great as the main system, but I don't see why they don't utilise modern technology in order to add a separate system that knows exactly where each car is at any point in time, and overrides the block braking system if it detects an issue. In my mind I see this system preventing any op or tech input from overiding / resetting the block system when it detects that there could be a collision. There would be a full digital track layout displayed on the control panel, detailing every trains precise location, (not just the block.) so the op / tech would be able to see exactly where the problem trains are. It would show all trains at all times, including trains removed and not in use.
To be honest, I'm just rambling, and I apologise for that, but I just find it frustrating that people say things like "the block system should make it impossible for 2 trains to be on the same block at the same time." When in fact history proves, that this happens.