In message , at 15:30:11 on Tue, 16
Aug 2016, Neil Williams remarked:

I wouldn't be so sure of that. ATO on a slow metro system is one thing, having
no one at the front on an express is another matter entirely. Until trains
have sensors at least as good as the human eye to see any obstructions ahead it
won't happen.

No train can stop in the distance its human operator can see to be clear.

Of course they can, how else would "calling on" signals work? (Albeit
recently not so well at Plymouth).
--
Roland Perry