Today I was stopped by someone who thought he was lost. He wasn't but was bamboozled by direction instructions from GoogleMaps. Later I looked at his route and realised that the worse was yet to come: Google routes along PSV only roads in the centre of Nottingham. Most of these roads access restrictions have been in force since 2006. Here's a link to an example of such a faulty route.
I then checked the same route in OpenRouteService and on CloudMade. Neither makes Google's execrable error, because of the superior OSM data, but both have their own peculiarities. OpenRouteService is positively averse to using the main route into Nottingham from Derby, and Cloudmade's router routes through a barrier=bollard on its shortest route option.
All three routers suffer generate the following direction in various forms : "12. Turn left at A6200/St Helen's St. Continue to follow St Helen's St" (this from Google). This is St Helen's St, but most locals would call it Canning Circus. I only knew where it was because I collected the street name a few months ago.
All in all it convinced me to take the proposal for storing destination sign information much more seriously now.