I think your work is very useful. I saw many times people using CAD drawings to create these emergency plans with these symbols and everything is a mess, without clear standard.
As a suggestion you could create a group of symbols related with other kind of plans such as orientation plans used in Shopping centers:
http://i.imgur.com/fWbVfhN.png
Or maybe you can create symbols for electrical plans:
Anyway thanks four your contribution.
