I'm quite sure this isn't a new idea. And I know there are arguments against, with regards to avoiding being patronizing. Which is important. However, I can't yhelp but feel that the sybmbol for accessibility (the stick fella in a wheel chair), is a little out dated, not not very 'inclusive'.
So what about something LIKE this.
Not this, cos its crap. I mocked it up in a minute or two just now. But to me an out streched hand symbolizes assistive services better than the stick guy.