As you ask: I do not know…but next is what I found so far.
180° turn: Turn using the exact same path for a return ! (Mirror)
- Magic Earth.
Does not offer 180° turns. - Here.
Does not offer 180° turns. - My car gps.
Does not offer 180° turns.
Except: Without nearby roads or roundabout than:
1.TRY to turn.(Keyword = TRY)
2.TRY to turn. - If turning: Get your next instruction
- If not turning: Continue(long) deviation.
IMO optimal:
- TRY to turn. Yes or No ?
- TRY to turn.
- If turning: Get the next instruction
- If not turning: Block the return path…
In the already shown (no sound) video (2’30) notice the ever increasing turn distance.
Triggers multiple recalculation & increasing distance turn alerts, solved by SET obstruction.