The route of the new trunk road is north of Builth Wells and just south of Newbridge-on-Wye in the County of Powys as follows:—
a route about 5.46 kilometres in length, starting at a point on the existing trunk road (A470) about 150 metres north of its junction with the unclassified road U1318 adjacent to the property known as Gwern-yfed-fach (marked A on the deposited plan) and then extending in a northerly direction to a point on the existing trunk road (A470) at its junction with the private road leading to the properties known as Dolwen and Woodcastle Farm in Newbridge-on-Wye (marked B on the deposited plan).