There is a system of “grand routes” in Europe with names like GR55, GR 34, etc More info here. They all have route markers that are two horizontal bars. In the photo you see blue over white. The GRs overlap with Caminos in many places, as you see here this part of the Camino Ingles is also part of the blue over white GR (I’m too lazy to look up the number) the thing that is interesting is the blue and white arrows on the sidewalk just past the sign. This is, I assume, based on the famous yellow arrows of the Camino. I have seen a lot of GR signs and this is the first one I have seen that uses this arrows thing.