The question was, "I am looking for an HGV Sat-Nav which will not route me down roads 'Unsuitable for HGV' - Will the ProNav stop this from occurring bearing in mind there is no official width restriction?"
A really good question and a tricky one to answer!
ProNav always tries to use preferred truck routes and absolutely avoids roads that have been marked in the map data as "banned" for HGV's. Additionally where there is no actual with restriction in the map data ProNav gives a very low priority to small roads when calculating a route.
We use Navteq map data as also used by Garmin, and many of the roads marked as "Unsuitable for HGV's" are include in that data. Does this mean that we leave out absolutely every road marked "Unsuitable for HGV", at this point possibly not, since many of these roads do not have an actual width restriction and we are relying on the roads being know to Navteq.
That being said the data right now is pretty good. We are also working with Navteq to report new or missing map data, so if anyone finds a road or any other issue making something difficult for large vehicles, they can report this directly to Navteq at:-
http://mapreporter.navteq.com/dur-web-external/
This way the data is continuously improved. Current feedback is that the truck routes most travelled are well covered, less is known about out of the way places.
So I guess the answer is that ProNav tries really hard to avoid the roads marked "Unsuitable for HGV", but just like looking at a paper map, if it is not on the map it does not know about it.
We think it is the best solution out there.