The scheme envisages improving the M4 Corridor around Newport. It includes construction of 24km of new motorway and a 2.5 km long cable-stayed viaduct crossing of the River Usk, as well as major remodelling of M4 junctions 23 and 29.
Costain has a 50% stake in a three way joint venture with Vinci Construction Grands Projets and Vinci subsidiary Taylor Woodrow.
Scheme development work starts immediately, leading up to an anticipated public local inquiry in winter 2016/7. Upon successful completion of the statutory processes, the second stage of the ECI work, construction, could start in spring 2018.