Construction of the Nui Vung Tunnel in the Cam Lam-Vinh Hao section of the North-South Expressway has been completed, according to the investors.

With a total length of 2.2 km, it is the longest mountain tunnel along the North-South Expressway.

In south-central Ninh Thuan province, the tunnel was built using Austrian tunnel-boring technology.

The Cam Lam-Vinh Hao section, stretching 78.5 km, runs through Khanh Hoa, Ninh Thuan, and Binh Thuan provinces.

With total investment of VND8.925 trillion ($371 million), the section is expected to be completed before April 30, 2024.

It is being built under the build-operate-transfer (BOT) model, with investors contributing VND3.786 trillion ($157.7 million) and the State budget the remainder.

The Cam Lam-Vinh Hao section will have four lanes and a speed limit of 80 km/h.

The tunnel has three lanes with a width of 14 meters, to be expanded to six lanes in the future.

It is the fourth-largest tunnel in Vietnam, following Hai Van, Deo Ca, and Cu Mong.

The investors held a ceremony last month to mark the center breakthrough in the tunnel.