Thanks for that information. That's very quick for a preliminary report.
It strikes me as really scary - that a signaller can override the safety system and allow two trains onto a single line.
I drive over 2 single lines several times every day, and it's never occured to me that an accident like this could technically be allowed to happen.
So much for interlocking then - I thought that a bi-directional line wasn't able to clear signals in both directions at once. It will be interesting to see how this system was configured.
Hmm. Very sad.
BW