I can see you thinking... what the * is that?
That were pretty much our thoughts too. We were still on the private roads of the farm. The alternative, the RN1, was really horrible, so whomever needed to pass trough here preferred to take the private roads, even if that meant paying a fee. But the farm wanted to prevent trucks from taking their roads, as they erode the sandy tracks and destroy them.
The road led trough a large marsh and spot in the middle they build that "thing". It was about 2,4meter high. Great way of preventing trucks from passing. But with our rooftop tent on we were about 2,6meter high.