Geograph - photograph every grid square

The cattle grid is at the crest of the road. The notice informs that it's private and should be "used at own risk"!
Now this is a public road so it seems odd that a cattle grid could be inserted privately in its surface at all. Surely permission must have been granted by the appropriate road authority for the construction of the grid but it seems most unlikely that they would allow that motorists be told that they take on the risk of harm or damage themselves.
Presently however, the grid appears to be in perfect condition.