Block systems are designed in such a way that in theory, it is impossible to allow 2 trains into the same block at the same time. Therefore eliminating the possibility of such a crash.
There will be no scenario that the system allows this to happen, it is designed in such a way that in any faulty circumstance, the ride is locked down.
As this system has worked so well, for so long, all over the world. Cars are not designed with high speed collision in mind, as there is no scenario in which 2 cars should be allowed to enter the same section of track.
The only way around these safety systems is manually. As anything else, including a catastrophic systems failure, would simply result in a complete lockdown, which would halt the full cart on the first lift. Which did indeed happen for at least 10 minutes.
After that time, in which the system was clearly working perfectly. Something extraodinary has occured. Somehow the safety system which was working perfectly has been circumvented and the train allowed to traverse the lift hill and enter an occupied block.
Every scenario in my mind brings this down to some form of human error. Although i must stress that it is pure speculation, and should be taken as such. But my two cents on this terrible incident is simply human error.
I would like to extend my thoughts to the people who have suffered ad a result of this once again. I have ridden the smiler several times and have enjoyed it immensely. Unfortunately the people on tuesday do not share our experience of the ride. I wish all a speedy recovery, both physically and mentally, legs may heal but mental scars take much more work and patience to come to terms with.
What if the exit proximity sensor for that particular block is loose in such a way that it is constantly being triggered by a peice of track/bracket making the central computer think the train has left the block. Not so extraordinary if you think about it. Things have come loose on this ride many times and that's only the documented stuff - not the bolts that are tightened on inspection daily and brushed under the carpet before the press find out.
this is most likely not the issue, there is more than 1 sensor on the blocks usually 2 or 3 if just 1 of them triggered the ride will E-STOP, for the block to reset the ride system will need to detect entry and exit of the block 1 faulty sensor would not cause this issue.
Yes you are right there are entry and exit proxies but if the exit proxy is faulty it will be either in a permanent on/off state (usually off) bearing in mind the ride suffered technical problems before hand with an empty car being sent around it would seem most likely to be sensory issue which would allow the possibility of trains entering the same block if that would be the case.
Other causes could be internal sensor error, water in wiring, water in plugs, water in circuit boards, trapped/chaffing wiring, poor sensor adjustment, bent sensor mounts, loose sensor mounts, heavy wear in the train causing deflection from the sensor, software defects, foreign objects, dirt...