Level 4 automation trains do in fact do obstacle detection and are capable of unattended operation: https://en.wikipedia.org/wiki/List_of_automated_urban_metro

Level 4 automation trains do in fact do obstacle detection and are capable of unattended operation: https://en.wikipedia.org/wiki/List_of_automated_urban_metro_subway_systems#Grade_of_Automation_4_Systems https://en.wikipedia.org/wiki/List_of_automated_urban_metro_...