Balfour Beatty’s joint venture with Jones Bros Ruthin (Civil Engineering) has secured the deal to build the 9.8 km A487 Caernarfon to Bontnewydd Bypass in North Wales.
The job, which was won with a bid of £65.5m, will include 18 structures comprising seven bridges and eleven culverts.
The new route will start at the Goat roundabout (A499 / A487 junction) and terminate at the Plas Menai Roundabout.
Subject to the completion of all the statutory processes and any public inquiry, construction work is expected to start in late 2016.
At the same time, Dawnus Construction in a joint venture with Ferrovial Agroman has bagged the ECI deal for the East Cardiff Link Road with a bid of £27.3m.
The link road will connect Cardiff Bay, home to the Welsh assembly and Wales Millennium Centre, with the A48 at Tremorfa.
The works will involve building a dual carriageway between Queens Gate Roundabout to the Ocean Way Roundabout to the east.
Due to the current layout of an existing dockland access road, two level crossings and a railway line to the neighbouring Celsa site, the alignment will require a high skew bridge to accommodate these.