^^
I know that, even I saw it on N Geographic Channel.
It supports collisions from backside as of now. The guard cabin also has this device.
There are many loopholes in the system.
There are instances which happened when I was travelling in a train to bangalore.:
The last three boggies of our train jerked off and the train was still running. We left the three boggies behind us and the driver of the train did not know that the last three boggies has been jerked off. The driver kept on running the train until we came to a curve, and the driver got
NO signal from the guard he immediately stopped the train all of a sudden!!
We all got off the train to find out that the last three boggies were actually
missing!!
After waiting for some time we saw the three boogies at a very far distance behind our train.
We had to back the train (that was the most difficult part because the train halted in a curve position and reversing it was not a child's play).
And they called gang man from the near by station to fix the three boogies together again.
It wasted around 2 hours.
What actually had happened:
1. The three boggies jerked off.
2. The vaccum meter still showed the driver that the train was normal will all the boogies.
3. The vaccum got re-created because a piece of paper had stuck in the mouth of the vaccum pipe from the last boogi (the one with the engine with it)
no offence
