Close-up of the billion-dollar mountain tunnel on Dien Chau highway

The Dien Chau - Bai Vot component project belongs to the North - South Eastern Expressway project, about 50km long, passing through two provinces of Nghe An (44.4km) and Ha Tinh (4.9km).

The Dien Chau - Bai Vot component project belongs to the North - South Eastern Expressway project, about 50km long, passing through two provinces of Nghe An (44.4km) and Ha Tinh (4.9km). The project started in May 2021 and is expected to be completed in May 2024. The project has a total investment of more than VND 11,150 billion, of which the investor mobilized capital is about VND 5,090 billion and the State contributed capital is more than VND 6,060 billion. Than Vu tunnel alone has an investment level of VND 1,350 billion. Than Vu tunnel is 1.13km long, with an investment capital of VND 1,350 billion, located halfway up the mountain, where the geology is complex and the rocks are strongly weathered. This is the item identified as the most difficult and complicated part of the North - South Expressway.

Than Vu Tunnel has a total length of 1.13km, passing through Than Vu Mountain, designed with a scale of 2 separate tunnels, each tunnel is 13.78m wide, the distance between the 2 tunnels is 45m. If the left tunnel is located halfway up the mountain, the right tunnel is next to a stream, with many underground water sources.

Close-up of the billion-dollar mountain tunnel on the Dien Chau - Bai Vot expressway

Mr. Vo Son Hai, Commander of the North Than Vu Tunnel Construction, Hoa Hiep Company Limited, said that Than Vu Tunnel is located in an area with weak geological foundation, strongly weathered rocks, scattered and interlaced. This is one of the construction items with complex technical characteristics and is related to the very important progress comparison line of the project.

“The tunnel is located halfway up the mountain, not at the foot of the mountain like other tunnels. The construction process encountered many difficulties, especially when working from the two southern ends of the tunnel to the confluence point, encountering a weak geological zone. If not careful, landslides can easily occur,” said Mr. Hai.

According to the Commander of the North Than Vu Tunnel Construction, the tunnel is designed to be permanent, with a reinforced concrete shell, constructed using Austrian methods. Inside the dark tunnel, the lighting system is constantly turned on for workers to work.

Right from the design stage, Than Vu tunnel was identified as the most difficult and complicated project on the North-South expressway. To meet the set schedule, contractors had to organize construction in 3 shifts, 4 shifts, during Tet holiday...

In early September, the inside of the tunnel had a landslide, hundreds of cubic meters of rock and soil fell down. Each time there was a landslide, engineers and workers had to use concrete spraying machines to seal the entire landslide area, then close the pipes, pump in cement to turn the entire loose block into an artificial rock block, and then continue digging. Throughout the entire construction process, similar incidents occurred many times, causing costs to increase, sometimes taking more than a month to handle.

Displacement monitoring equipment is installed in many locations in the tunnel to monitor whether the structure is shifting or experiencing any problems so that timely measures can be taken.

Parallel to the right tunnel, the left Than Vu tunnel, 1,087 m long, is currently under construction.

After 15 months of construction and overcoming many difficulties, Than Vu tunnel was officially opened on the afternoon of October 14. After the tunnel opening ceremony, cars were able to travel from the south of the tunnel in Nghi Loc district to the north of the tunnel in Dien Chau district.

The opening of Than Vu tunnel is of great significance in shortening the time and cost of transporting materials for the construction of the North-South expressway project through Nghe An, ensuring the project is completed on schedule.

According to the plan, in phase 1, contractors will complete the construction of the right branch tunnel for two-way exploitation, build the tunnel lining and underground drainage system for the left tube to act as an escape tunnel. Phase 2 will complete the entire tunnel to a complete scale with 6 lanes for motor vehicles.