Farm fencing

The B426 (B in Germany = A in UK; high number means it's relatively short) runs through a number of villages. One of them, quite small, is not really built for modern traffic. The centre is so narrow, that big trucks can only pass one after the other, never two from both sides at once.
This, and the high number of cars passing the village, has finally led the German government to approve a new bypass around it. 2km, and some underpasses and bridges. And a new round-about. The inhabitants of the village will be happy when the bypass is ready.

Anyway, the work is done in stages, with a number of construction sites.
And what was new to me was the farm fencing. I know iron construction fences. But I can't remember to have seen 3-estate rails being used.
The fences will stop big machines, but only if the driver fancies to stop. They definitely won't stop any animal or human being.
To me these fences look more like alibi fences.