Wiktionary
fixed route
n. A form of public transit bus or ferry service without any regular deviation from schedules or course
Usage examples of "fixed route".
Which pass would take them over the Andes, and yet not be out of their fixed route?
It is a bureau of the Communist government and its function is to get those Yankee dollars in advance, channel you through a fixed route, then spill you out at the far end almost as ignorant of their country as when you started.
Flingers were common aboard ships that ran a fixed route in heavily populated systems.
The locomotives were much simpler than the road-engines being developed at the same time, and the inflexibility of a fixed route was offset by the lesser rolling friction on iron rails.