robroy:
Lucy:
As far as I remember (and it was 20 years ago that I was running out of Shaftesbury), they’re both “Unsuitable for HGV” but from opposite directions, if that makes sense? So the Melbury Abbas route has a blue sign next to it at the other end, while the A350 doesn’t - or certainly didn’t.I once got stuck on the hill on the narrow bit of the Melbury Abbas route, going the “wrong” direction - at rush hour on a Monday morning. Bring back dodgy twin-splitters in Ivecos being driven by 24 year old girls with bugger all experience!
Aye you’re right Lucy, the A350 is for n/b and the Melbury Abbas road is for s/b HGV traffics.
That hill you’re on about is known locally as ‘Zig Zag’ hill, but I think that actual route Melbury road avoids it, it’s on a B road afaik, but the designated route is unclassified road…I’m blagging this btw , it’s just what somebody told me.
Not quite.
I cut my teeth on the A350, my first job in 1993 was from Llanelli or Ebbw Vale with tin plate down to Upton (just outside Poole) and the scraps back to Llanelli. I drove a Ford Cargo daycare with a top sleeper, and a twin splitter. I remember to this day dropping down to East Knoyle and thinking “what the actual fxxk!!!”… of course, it got much worse after Shaftesbury… 
From 2004 I spend 10 years driving around the area collecting milk, mainly in artics.
The route through Melbury Abbas is tricky, but rewarded with a clear passage to or from Blandford Forum. There is a way around Melbury Abbas, turn of by the airfield, and follow the road till Ludwell, where you turn left onto the A30.
Zig-zag hi is not the same road. That is on the road to Sixpenny Handley, or Cranborne, and I would not suggest it going from Shaftesbury (I.e. uphill). I’ve done it downhill many, many times, but only with steering axles… 
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Taking (part) loaded tankers up steep hills is a nightmare, and best avoided.