This piece is unique in its approach. We have no other roadsign where the man is working from a pit.
Explore this site a bit further and You'll notice that no other man steps into his pit. A pit is actually never part of the picture. Men at work are normally surrounded by heaps (see Argentina).

I'm wondering what he did with the sand coming from this pit? That must form quite a mound. Where to did it go? I realize that we could ask a related question about the heaps — where did the sand come from? — but I've always thought that the pit was located outside the frame but near enough for the man to throw it back. That couldn't be the answer here: it's too difficult to lift and throw spadefuls of earth.