The sewer and the railway are immovable objects, hence the problem. The rental truck depot up the road contribute to the problem. In theory this could be reloc

The sewer and the railway are immovable objects, hence the problem. The rental truck depot up the road contribute to the problem. In theory this could be relocated but this has to have a cost greater than the loss of a few rental truck tops. There is a road junction next to the bridge meaning the parallel road limits the options for slowing down tall vehicles before the bridge. Thus far in this comment thread your comment has been the only one that sheds some light on the situation.