Hello
PERS (Pedestrian Environment Review System) was co-developed by Transport for London and TRL and has been used to assess walkability extensively around London and the UK (over 200km of street assessed).
We recently launched a new version of PERS (v3) which has built in GIS, photo georeferencing and automatic quick win generation.
You can watch a demo of the PERS 3 here:
http://www.youtube.com/watch?v=32uu1kB-d8s
Let me know what you think?