|Length:||11.7 miles (18.8 km)|
|Meets:||B4044, A420, A415, B4016, A4130|
|Route outline (key)|
The route starts on the B4044 (former A40) at Farmoor. It heads south along Farmoor Reservoir (which is only just visible) before climbing to Cumnor. There is a one-way system here and eastbound traffic continues along Oxford Road before having to TOTSO right along Glebe Road then left to regain its direction. Westbound traffic uses the third side of the triangle.
On the edge of Cumnor the B4017 crosses the A420 at a Diamond interchange before going through Henwood and Wootton. It skirts the former RAF Abingdon before going under the A34 without a junction and enters Abingdon itself. It reaches the A415 in the centre of town and is forced to turn left (although that road is two-way).
Originally the B4017 ended here (or at least nearby: it continued ahead along Bath Street to meet the A34 High Street). However, when the A34 Abingdon bypass was built the B4017 was extended along the pre-bypass route to the south. The B4017 therefore multiplexes along the A415 west through Abingdon (there's a one-way loop for southbound B4017 traffic to follow) before turning left at a double mini-roundabout to head south. It crosses the River Ock almost immediately before heading through Drayton, after which it goes under the A34, once again with no junction. This was a temporary terminus of the A34 bypass at one point and a disused slip road is still visible.