An experienced railroader can weigh in and correct my terminology but:
Essentially what you're describing is the way that many railroads used to operate, trains, except in rare situations always ran in the same direction on the same tracks.
What this meant though was that you were limited in how many trains you could run in either direction (imagine a situation say where commuter trains are running into a city. Outbound trains in the morning may be infrequent, but inbound may be frequent. However, since you have multiple stops, express trains would get held behind the stopped trains. By permitting both tracks to be used in either direction, you can easily have express tracks on the left hand tracks and locals on the right hand. Then reverse things in the evening.)
Note that even with this, it was always possible to operate "against" the direction with specific train orders.
As for one-way tracks. Sometimes you see this with freight lines, especially where two railroads have merged. What formally may have been a bidirectional single track may be used in one direction only due to its grade (i.e. heavy loads taking the longer, but less steep grade up to the top, and other loads coming down on the steeper track.)
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