Nothing strange about sitting on a guard rail, except this was the guardrail of the road that crosses the motorway here. He'd been sitting on a bridge, staring into space.
So I jumped back into the car to have a chat with him. Barely underway, his wife called and apologized for not responding. No worries, I interrupted here, are you missing your husband?
"Yes, no, kind of, what's going on?" - "He's sitting on the bridge!" - "Aah, don't worry, he was taking a walk and probably overdid it again"