Comment by avar

If you pass over a moderately complicated junction at low to moderate speed there's a good chance the signallers either can, or just by default will, derail you safely.

The phrase is "trap points". A correctly designed junction, where possible, will have points ("switches" if you're American) that default to leading to a dead end, with buffers and then nothing important. If you enter that track section without a signaller choosing where you should end up, that's what will happen.

The reason isn't for the implausible scenario of train theft, it's to reduce the consequence of errors. A wrong side signal defect allows a train into the junction without points being set - what happens? With trap points the train is derailed, probably at low speed, not directed into traffic. Or a driver misses a danger signal, same outcome. Expensive but probably everyone walks away.

Except that you don't control the signaling or the switching, meaning you can't choose where to go and you will very quickly be noticed and depending on the level of signaling automation either stopped completely or at least shunted to the place you can do least damage.