The enhanced route, which was delivered on time and within budget, will improve journey times and increase safety on this section of the A470 as a result of a number of measures including the removal of the existing sharp bends, bridge restrictions and offering safer overtaking opportunities.
Construction of the new route – which was carried out by local contractors Alun Griffiths on behalf of the Welsh Government - started in February 2010 and involved a 180 strong workforce.
Speaking before the official opening, Carl Sargeant said:
"This improved route plays a key role in the Welsh trunk road network connecting North and South Wales and serving the local communities.
"With the removal of the existing bridge constraints, severe bends and the provision of safer overtaking opportunities for drivers as a result of this scheme, we will see a significant improvement in safety and journey times.
"This scheme, which is another Welsh Government road project that’s been delivered on budget and within time, is further confirmation of our commitment to improving the transport infrastructure that will in turn help increase mobility, enhance connectivity and assist economic growth across Wales."
Local school children were invited to an art workshop during the construction process to provide ideas for a sculpture that will be a lasting feature on the new route.
Cllr Geraint Hopkins, Powys County Council, said:
"The new road provides a welcomed safer link in mid Wales and will greatly improve the quality of life for residents living near the old road. The project has been fully supported by the council, which has protected jobs with local contractors and suppliers.
"By bypassing the low railway bridge at Cwmbach, the new road will enable all traffic to use the A470 and will much improve resilience in the trunk road network. Over time, planted trees and shrubs will mature and the road will fit well into the rolling landscape."
The new route runs northwards on the west side of the existing A470 trunk road, from south of the entrance to the Young People’s village at Court Farm.
Adjacent to the Heart of Wales railway, the road crosses a deep ravine on a three span bridge and crosses the existing A470 on a new bridge before continuing northwards on the east side of the A470 crossing the River Ithon on a new bridge and joining the existing road before entering Newbridge-on-Wye.