wakey151291

Looking at further pictures it would appear the casting of the bogie assembly has cracked all the way around, on the bogie that's on the floor at least, this could just be one of the bogies that has broken off afterwards from when the train has hit the floor or the strain of the derailment. Maybe the trigger is a wheel failure, bearing siezed or worn out, bolts come loose, many causes are possible. If the ride jammed up the lift hill the day before, although could be completely unrelated to the incident itself, the two could link together especially if the fault caused the train to sit lower than usual and the dog of the car wasn't catching the chain for example. Things that HSE will look for, as well as maintaince records, are witness marks on the track for wear patterns and bolt scoring etc, condition of the bearings for wear and under greasing, loose bolts, missing locking pins/clips, the breaks on the bogies if they are clean breaks or rusty breaks - rust indicates the break has been there for some time. One thing that's for sure - it's a good job the train landed the way it did.

With limited information it's difficult to judge how the wheel assemblies are set up on this model, and the exact circumstances behind the detail but looking at the picture of the bogie on the floor (which is difficult to view in detail at best) the swivel pin looks to have sheared off or if the bogie is upside down perhaps the bearing assembly broken. The break point doesn't look clean which would suggest there may have been an existing crack, and it could be likely that the other bogies are in a similar condition. If the swivel pin has sheared the bearing assemblies may be under greased and are siezed. Where the train appears to derailed (at the bent support) it looks like the train is undergoing a large amount of stress here as can be seen by the wheel marks on the track. The train will be twisting, picking up speed and undergoing high Gs. If the other bogies are in the condition the one on the floor is in then it's possible one bogie failing will be enough for the others to fail as well. It's hard to say this is 100% accurate Until more detail is released.