#1032 "The stop bars at each runway entry point are not individually selectable, the set up is for low vis operations where all runway entry points are blocked."
This infers some reliance on visual detection of incursions in good visibility.
Detection must not be presumed in every situation; night, background clutter from airport / runway lighting, foreground light-clutter in the flight deck, and human limitations - detection, perception, understanding, and time to act.