Have hacked together an interesting feature where we can avoiding certain turns like left_turns. Currently it still has some unexpected behaviour (for T-junctions) and is rather slow for longer routes, as the junction calculation stuff is done while the graph exploration, but it is really fun and interesting which routes are found:
Update: this matter is a bit more tricky as there is sometimes no reason to avoid certain left turns, e.g. for a T-junction coming from bottom, going to left - this is a complete different situation compared with a normal 4-road junction where oncoming traffic needs to be “crossed”.