One thing worth noting about that map is that it's only for major roads that appear to be the responsibility of Transport Scotland - local areas have their own snow clearing coverage e.g. Here is the map (sadly without automatic updates of gritter locations) for Fife where I live:
http://arcgisweb.fife.gov.uk/LocalViewEXT/Sites/publicWinter...
Mind you - the road where I live (which to be fair is rural and up a hill) was blocked for about a week the last time we had any serious snow and it was some local farmers with JCBs who actually cleared it.
