|Location Map ( geo)|
|From:||Pembrey (NW) (SN417020)|
|Distance:||11.9 miles (19.2 km)|
|Meets:||A484, B4308, B4309, B4306, B4310|
|Route outline (key)|
Starting on the A484 on the coastal plain on the northern edge of Pembrey, it heads northeastward, crossing a narrow bridge over a dismantled railway line before bearing left to avoid climbing the steep hill ahead. The road remains fairly flat as it winds to the northeast and presently reaches a T-junction on the B4308. There's now a multiplex for about a mile to the right into the centre of Trimsaran, although through traffic is advised to take the first left turn off the B4308 to cut off the corner and avoid the village.
The B4317 regains its number by turning sharp left at a mini-roundabout by the leisure centre and heads north. After meeting the other end of the "bypass" mentioned in the previous paragraph it passes Ffos Las racecourse (built on the reclaimed site of an opencast mine). Access to the racecourse is provided at a roundabout where we turn left and pass through Carway. There's an unexpected left-hand bend and we descend into the valley of the Gwendraeth Fawr and reach the village of Pontyates and a T-junction on the B4309. Signs show a level crossing immediately to the left; although the gates are still here it is obvious the railway has not been used for some time. There's a short multiplex to the right up a hill then the B4317 reappears by turning left.
The road now continues upstream along the valley, parallel to the disused railway line, for the rest of its length. To begin with, the road runs halfway up the left side of the valley before descending into Pontyberem. The B4306 intersects our route at a staggered crossroads, then the B4317 follows Station Road alongside the railway line; no trace remains of the station. After leaving town the road follows the railway line for a short distance but continues along the valley bottom to reach Cwm-mawr, where it ends at a T-junction on the B4310. The railway line didn't go any further either.