|Length:||4.4 miles (7.1 km)|
|Meets:||A465, B4246, A465, B4558, A40|
|Route outline (key)|
The A4077, when used in conjunction with the new dual-carriageway section of the A465 Heads of the Valleys Road past Govilon, can be considered a handy, though not particularly good, alternative route for A40 light traffic wishing to avoid passing through Abergavenny. However, it is narrow and twisty for much of its length; and a better bet for such traffic to and from Crickhowell is the A4143 link between the A465 and the A40 on the west side of Abergavenny town.
Our route starts on the modern A465 at Glanbaiden (immediately west of the traditional Brecknockshire-Monmouthshire boundary), where it leaves the north side of a roundabout recently much enlarged in preparation for the next stage of the Heads of the Valleys Road dualling (from here to Brynmawr). The B4246 which terminates on the opposite side of this roundabout is the old A465 from Abergavenny.
The A4077 immediately takes a wide sweeping bend around to the left to pick up the original course of the old A465 Abergavenny-Merthyr road into Gilwern. At the Beaufort Arms in the centre of the village, the road forks, with the pub itself at the centre of a mini partial gyratory.
The left-hand branch continues the old route towards Merthyr for a further 300 metres before it rejoins the modern alignment of the Heads of the Valleys Road by the Navigation Hotel at the west end of Gilwern (the junction here is a limited one, however, giving access only to and from the eastbound A465). The right-hand branch, meanwhile, strikes off northwestward as the mainline heading for Crickhowell. The high bridge carrying Crickhowell Road over the River Clydach in Gilwern is a relatively modern one (officially opened on 18 July 1938): pre-war maps show the A4077 connecting to the A465 much more circuitously via a narrower and less elevated crossing about 150 metres southwest (upstream) of here.
Leaving the village behind, the road follows the course of the River Usk for much of its route. It seems to climb steadily away from Gilwern, and the river is rarely in sight as the road passes through woodland. The twists and turns soon even out, however, and the road widens a touch along a straight that drops us down to the river bank, again partially hidden by trees. We meet the B4558 at traffic lights, and turn right to cross the single-track bridge (a second reason for the traffic lights) into Crickhowell. We climb through the pretty town via New Road to end at a T-junction with the A40 just west of the town centre.