Basically what it says in the title. There's probably already a way to accomplish this, but this idea popped into my head and I figured I'd share it. I think it'd be a nice little addition, especially for map creators, to have the possibility of setting a decal road to be a one-way road. Mainly just as a way to tell the AI that a certain road may only be driven one way and not the other. It'd be especially useful for track maps and maps where the roads are only designed for a specific direction, because the AI love to get turned around on accident and then drive kamikaze-style in the wrong direction. The entire idea came to me when watching FailRace's "Wreckoning 15" and when I was building the track for Conquistador Gorge, as the AI vehicles would get turned around (either by way of crashing or losing grip) and head in the wrong direction. If there was a setting in the Decal Road menu to tell the AI that the road is meant to only be driven in one direction, it'd make it so the AI (even if they get spun around) travel in the direction that the road was intended to be driven on instead of going the wrong direction. I could also see one-way decal roads being useful in realistic city-based maps. Just an idea.
I was just thinking about this the other day. I attempted to use waypoints to get two way traffic across a bridge, didn't work out too well. Great idea and having this would make AI shenanigans totally epic.