The two sections, which have a combined length of 83 kilometres, will cost nearly VND4 trillion (US$188 million) to expand.
The upgrade, slated for completion in 2015, will increase the motorway’s width to 20.5 metres, allowing vehicles to travel at a maximum speed of 80 kilometres per hour.
Bridges along the highway are also to be upgraded to accommodate the greater width and withstand heavier loads.
The same day, work also started on the expansion of a 52-kilometre stretch of National Highway 1A in Quang Ngai province.
The VND2.7 trillion (US$126.9 million) project is expected to be completed within two years.
National Highway 1A is the most important trans-national motorway in Vietnam, running over 2,300 kilometres from Lang Son to Ca Mau.
In recent years, it has deteriorated and the Government has launched an initiative to upgrade the entire highway in order to accommodate increasingly heavy traffic.