Ludgershall - Chiseldon
The A346 starts as a small rump branching off the A342 west of Ludgershall for a mile or so before meeting the A338 in Collingbourne Ducis. I think this used to be a TOTSO but it's a roundabout now. It then disappears from view before reappearing at Burbage, where it picks up primary status from the A338.
The A346 runs to the west of Burbage on a single carriageway bypass, before picking up the old road to the north. It then heads over the Kennet and Avon Canal before burrowing into thick forest. It runs through forest for several miles before emerging at a sharp drop down to Marlborough, where there's a brief multiplex with the A4.
North of Marlborough, the A346 now runs on the old route of the A345 along the Og Valley. At Ogbourne St George it meets the main Roman Road from Winchester and runs along its course for several miles, crossing the Ridgeway en route. It ends at a roundabout with the M4 just outside Swindon, the road ahead being a rerouted A419.
The original route of the A346 was along the present A338 from the A344 (present A303) near Shipton Bellinger north to Collingbourne Ducis. It was given its current route in 1935.