But it "started" at a roundabout? That could be telling...
Any chance that at the approach, the first driver practically stopped, even though NOBODY is on the roundabout???
My 75 year old father gets pissed at people doing that: "Oh dear, a roundabout with nobody on it, I'll practically stop, and give way, in case there is an invisible car I should give way to..." and he doesn't even drive a ute 🤣
Most people on the road are UNAWARE of what is going on around them.