mostly on isolated metro systems where the infrastructure is expansive enough, there are no level crossings, and the line operates effectively in a vacuum.
Also, critically, metro systems are relatively “dense”, so you can have a human respond to an exception quickly - you’re always in a populated area with not much space between individual stations.
Also, critically, metro systems are relatively “dense”, so you can have a human respond to an exception quickly - you’re always in a populated area with not much space between individual stations.