The sign says "Detour Ahead". But there are arrows drawn on it. Just behind it, the road is closed. I suspect they need a sign that merely says "Detour" with a left arrow on it.
On the other side of the road closure, it gets worse. The road closure makes it a dead end spur. Instead of putting a sign at the intersection, the sign is half way to the closure. The sign says "Detour Ahead" but with no arrows. There is no detour; this is a trap.
This person has a cool bike horn, albeit instlled upside down.