|Location Map ( geo)|
|Distance:||12 miles (19.3 km)|
|Meets:||A4, A365, B3105, B3107, A363, A366, A361|
|Route outline (key)|
The B3109 is a largely rural B-road on the western edge of Wiltshire.
It starts at a triangular junction with the A4 at Corsham and heads southwestwards via Rudloe and goes over the top of Brunel's Box Tunnel.
The road continues to climb to cross the A365 at a staggered crossroads controlled by traffic lights, known as Box Fiveways. It continues across undulating ground to bypass South Wraxall before going through Bradford Leigh and crossing the B3105 into Bradford on Avon. The road becomes narrower and is lined with historic buildings.
Shortly afterwards a mini-roundabout is reached and the B3109 splits. Turn left along the ex-B3388 to reach the B3107 or right (signposted Town centre) to reach the A363. Through traffic presumably turns right (this is the original line of the road) and the B3109 multiples with the A363 through the town.
After crossing the river and the railway line the B3109 reappears on a gyratory and continues south as a form of western bypass for Trowbridge. It crosses the A366 at Wingfield before entering Somerset and terminating on the A361 on the edge of Rode. The 1922 Road Lists give Rode its former spelling Road.