Rear view
This is quite a big and prominent sign. With its large black, capital lettering and its yellow background, it doesn’t want to be missed. You can see why, if I were a wall I wouldn’t want lorry drivers driving into me either.
Obviously, the fact that it’s there means that the wall has been driven into plenty of times. Most lorry drivers are pretty good at reversing, what with all the tests they have to take, but perhaps they were just put in an extra-long lorry that day.