Ok, so here is the bridge that crosses the River Tamar. It looks...

Ok, so here is the bridge that crosses the River Tamar. It looks far more solid from this google map angle.



A sign like this would indicate that Heavy Good Vehicles could not use the bridge. FYI, there is no sign over this bridge.



Actually, that sign was taken from Florence Road in Callington. It is stopping trucks taking a small detour around the town. So it would seem they are actually ok to drive through the town of Callington down the A388 (no sign restrictions).

Now heading South via Callington allows the Tamar River to be crossed via the A38



No issues there.

And if they wanted to go around Callington, instead of through it, they can loop around via Kelly Bray without adding much time to the journey. I would note that there are also other options/detours that could also bypass Kelly Bray if need be.

42 mins with bypass
35 mins without bypass
48 mins over the smaller bridge

So to say it is impossible or uneconomical is a bit of a long bow imo. Some locals may not like it, but that doesn't mean it isn't possible.