|To:||Winterbourne Abbas (SY620904)|
|Length:||8.9 miles (14.3 km)|
|Meets:||B3155, A354, A35|
|Route outline (key)|
The B3159 is a largely rural B-road in south Dorset.
Originally it started on the A37 (now A354) in Upwey. However, on the opening of the Weymouth Relief Road in 2011, the B3159 was extended along the now-bypassed A354 from Broadwey to Manor Roundabout and the previously bypassed section of the A354 along Dorchester Road into the centre of Weymouth to end on the coast, specifically at a gyratory on the B3155.
Continuing north from Upwey, the B3159 crosses the South Dorset Ridgeway before passing within a few hundred yards of Maiden Castle. It then continues west along the valley of the South Winterborne via Winterborne St Martin and Winterbourne Steepleton to end on the A35 at the eastern end of Winterbourne Abbas.