Just a small nit: almost all high-speed systems still use fixed block signalling, but with in-cab signal indications as you say to give more warning time (and a

Just a small nit: almost all high-speed systems still use fixed block signalling, but with in-cab signal indications as you say to give more warning time (and a constant reminder rather than having to spot a signal as it goes by in a flash). Moving block turns out to be much harder to implement than expected; it's included in the European Train Control System's level 3, but even most new installations are of level 2 (fixed block with in-cab signalling).