I've notice this happen before. Its like when I upload something really useful someone comes along and actually steals the whole caboodle - link and all! LOL!
Lets try that again (and they're really nothing compared to the ones I've just seen you upload)
I have a full set of these, from 1-15 steps.
14 step shadow.png
Like I said - a bit plain compared to yours. I was thinking, however that you could do a sort of planking texture in a similar way, and stamp it down on the basic walkway shape to cut out a bit of that drawing job on the walkways?
I also have this:
cellar shadow.png
and this
Full Banister.png
and it wouldn't take very much effort to make all kinds of things that would make relatively short work of the boardwalk thing.
But I see that you can probably do that all by yourself already with your existing collection