Good Lord Charlie!,
I hope you are recovering OK.
It's not good at all that you were injured because someone else couldn't give a D**n
about the other people on site.
Personally if that was me, I would be at the guy like a Doberman until the hazard was removed.
Accidents like this, Charlie, just shouldn't be happening, especially when it could have been easily prevented.
Just as an aside, there is a designated area for the delivery of shingle and other such Building materials here, on Construction sites, however, in this case the guy that put the shingle there in the first place should have known better.
Let's face it, these days if you're not young, you're old - Red Green