Work has begun on the long-awaited A6 dualling scheme between Drumahoe and Dungiven in Co Londonderry.
The 15-mile scheme – representing an investment in the region of £220m – will include a bypass off Dungiven, with roundabouts connecting it to existing roads at either end.
When complete, the A6 upgrade will link Londonderry and Belfast via a dual carriageway.
Work is expected to take up to four years to complete.
Sinn Fein MP Elisha McCallion said: “Other sections of the A6 are well under way and when completed, this road upgrade will dramatically reduce journey times between Derry and Belfast.
“This is vital for growing our economy and increasing connectivity between Derry, Belfast and a direct link to Dublin.
“It will also make it much easier for visitors and tourists to travel to the city.
“This, along with other key infrastructure projects such as the A5 and the transport hub at the old Waterside train station, will all enhance this city and district for locals and others.”
Some 15,000 vehicles travel on the A6 every day.
The Department for Infrastructure’s Northern Divisional Roads Manager, David Porter, said the route was a strategically important as it connects the north west to Belfast and beyond.
He added: “This very significant investment will greatly improve road safety and journey times by reducing congestion.”