One of three key sections of the Belfast-Londonderry road formally opened yesterday.
The four-mile dual carriageway from Randalstown to Toome has been open to traffic since last month but has now been officially unveiled.
It replaces a twisting section of the A6 Moneynick Road, one of the most dangerous single carriageways in Northern Ireland.
The new road links into the two-mile Toome bypass, finished in 2004, which in turn will lead to a new four mile dualled road to Castledawson.
Work is under way on that latter section of the A6, to open in 2021. Those two schemes cost £185 million.
They are two of three major improvements on the main route to the Northwest.
The third dual carriageway is the longest, a 15-mile stretch that is being built from Dungiven to Drumahoe, on the outskirts of the Maiden City.
When all three parts are open in 2022, almost 50 of the 71-mile journey between York Street, Belfast, and Altnagelvin, will be motorway or high quality dual carriageway. The latter road prohibits right turns across the central reserve, akin to a motorway.
The upgrades will leave an 18-mile single carriageway over the Glenshane Pass, but it has lower traffic levels and climbing lanes.
Gareth McLaverty, contracts manager at Graham, who built the road with Farrans, said they were “delighted” to finish the first phase.
He said: “It will help to strengthen the links between Belfast and Derry/Londonderry and will bring the long-term benefits to road users and the local community of reduced journey times and improved road safety.”
The road was delayed by environmental objections. Mr McLaverty said: “We have done our utmost to limit the environmental impact. An acoustic barrier, re-grading of agricultural land to reduce the impact of embankments, sustainable drainage ponds, farm accommodation tracks, over-bridges and underpasses, landscaping planting and boundary treatment are among the work carried out.”