Ouch! I can think of at least one major railway crash that was caused by a signalling fault.

And even on small country lines, if you get the signals wrong, you could have the points set the wrong way and get a derailment.

And many country lines were single track, which meant you had to have only one train on the track at once. Often, they had batons that were handed over at fixed points, and you could only go onto the track if you were holding the one and only baton.

I HATE writers who get their facts wrong.