On my way to work I pass near the strange sign. Well, it's not the sign itself that is weird, but the place in which it had been placed. There is a big roundabout nearby, but the sign is far off the road. The only nearby thing is a trodden path that many people use as a shortcut.

The mystery is even greater when you have a closer look at the sign. It has three warning lights that might be even powered up. And it does not look as a temporary sign (as it is well mounted in the ground, and was there since I can remember).