In my own setup, I contemplated which direction my trains should traverse their track based on planned spurs and with some regret, the direction arrow on my MTH DCS Commander pointed. If you put the train on the track in front of you, and the arrow in the display points to the right, the train goes that direction. A mistake? IDK!
But for the purpose of this question, four conditions please?
1. "Figure 8" (and any extended variation) should not be considered "both directions", as by design it does not have a delineated direction, and therefore is not applicable to this question.
2. "Out-And-Back" is clearly a situation of "both", and is a reasonable response.
3. The question is premised on the fact that the engines are generally (meaning without special manual intervention) in one direction...their forward-facing direction. Engines running in reverse, though admittedly allowed both in scale and real-life, is not the intention of this question. What direction are the headlight facing?
4. Does it differ below the equator? {This is a joke folks, referring to the fable that toilets flush the opposite direction in countries like Australia, which is not true.}
So, looking over-head of your track layout, regardless of how complex, is there a definitive direction your layout is designed (clockwise or counter-clockwise)?
Overhead pictures MOST welcome!