Comment by N19PEDL2

> The accident from January this year in Spain was also a collision, but because a train derailed, while another train passed it. This can't really be prevented by a current train control system, other then not allowing the derailment to happen in the first place.

Or by putting all the signals to red after the derailment of the first train so as to stop all the circulation on the line, which seems not to be the common practice in Spain unfortunately.