Been meaning to comment on the changeset.

Access tags should only be used for legal restrictions and not just because they are not suitable. So hgv=no or maxwidth should not the used in this case. BTW that is a very odd number in the maxwidth tag. 

You can add a width to the road which routers should use to determine suitability. But the best we have for the blue signs is just to add a note tag.

But at the end of the day a satnav is just a tool that requires skill to use effectively, if a drive encounters such a sign they should use their judgement. These signs, as any driver knows, are a very common feature.