The Welsh Government is seeking a partner for a £500m road project using a public-private partnership model.
Tenders have been invited for the design, construction, finance, operation and maintenance of a new section of the A465 to the south of the Brecon Beacons.
A special purpose vehicle will be set up to deliver the scheme, which will connect the northern points of the south Wales valleys.
The wider upgrade of the A465 or ‘Heads of the Valleys’ route has been under way since 2005, with four sections of the road completed.
The new tender is for the final two sections (five and six), with construction set to begin later this year and due for completion by 2020.
A 17.7 km stretch of road will be upgraded from a three-lane single carriageway to a two-lane dual carriageway, while a further 2.2 km of new roads will also constructed.
The successful bidder will be tasked with building or upgrading a host of new structures along the route, including 35 bridges, 41 culverts and 40 retaining walls.
Carillion had been responsible for section three of the route (pictured), which saw the contractor build four junctions, eight bridges, six large retaining walls and three underpasses, as well as a rest area at the road’s highest point and 5.1 km of new cycleway.