The Nha Trang Cam Lam expressway is 50km long, designed with 4 lanes and a speed limit of 80km/h. The project includes tunnels that are nearly 1.5km long overall. There are 500 bridges and culverts constructed on complex terrains and geology along the route.
Son Hai Group has achieved remarkable success in transportation construction by putting the expressway into operation ahead of schedule, starting from May 19, 2023, which is 3 months ahead of the original plan. Notably, the Do San Tunnel, one of the critical links on this expressway, surpassed the construction schedule by 6 months.
To achieve this achievement, Son Hai Group has utilized various state-of-the-art technologies. Although modern technology implies higher costs while the unit price remains unchanged, Son Hai Group has spared no expense in investing billions of VND in modern equipment from advanced countries, such as the material feeder machine used in the construction of asphalt concrete road surface. This equipment is the first of its kind used in Vietnam.
By using this technology, Son Hai Group is able to eliminate road marks, resulting in a smoother road surface. The asphalt concrete layer, processed through this equipment, is heated and mixed again to create a more even concrete layer, thus achieving better road surface roughness.
Automatic median barrier spreader
The automatic median barrier spreader, manufactured in the United States and transferred to Vietnam by specialists, is one of the most advanced and modern devices in Vietnam, specifically for the expressway project.
Based on the practical observations of Government Electronic Newspaper reporters, this machine runs between lanes and “dispenses” a continuous seamless concrete barrier strip that not only meets high quality standards but also saves construction time and increases productivity.
This machine is called Power Curber 5700. As introduced by the manufacturer, 5700-D is the latest generation of the best-selling slip-form concrete machine in the world.
Construction of Do San Tunnel using Austrian method
The Do San Tunnel project began in November 2021. To expedite the project, the investor has arranged the most experienced contractors in tunnel construction. The construction site is equipped with 4 tunnel excavation and reinforcement fronts, as well as 2 fronts for tunnel door reinforcement. Construction operations are organized in “3 shifts, 4 teams” continuously, with an average tunnel excavation rate of approximately 10 meters per day.
To accelerate the tunnel construction progress, Son Hai Group maximizes the workforce with over 500 pieces of equipment and 1,500 workers, divided into 3 shifts working both day and night.
According to Son Hai Group representatives, the company has applied the cutting-edge NATM tunnel construction technology, the leading modern method in the world, to the Do San Tunnel project. To complete this item, hundreds of skilled workers, employees, and hundreds of modern machines work around the clock. As a result, the tunnel was completed and made operational in May 2022, 6 months ahead of the approved schedule.
NATM (New Austrian Tunneling Method) has become the most widely-used underground construction method worldwide in recent years. NATM maximizes the natural properties of the terrain, helping save considerable costs associated with support materials and reducing construction time. Moreover, NATM demonstrates excellent resistance to geological pressure in earthquake-prone regions. In fact, it is an outstanding building method for numerous tunnels around the world.
Particularly, during the construction of Do San Tunnel, Son Hai Group proposed changing the entire design to lay asphalt concrete to eliminate noise from vehicles passing through the tunnel and improve aesthetics. This is also the only tunnel in Vietnam with a complete asphalt concrete layer. As a result, when driving through Do San Tunnel, there is no longer the “roaring” sound as in other road tunnels.
Pocket money spent on widening road shoulders
In addition to investing in modern technologies, Son Hai Group has also used its own funds to improve the project for the convenience and safety of road users.
Specifically, Son Hai Group has invested extra funds in widening the road shoulders from 50cm to 1m and reinforcing them with 1m of concrete on both sides of the nearly 100km long Nha Trang – Cam Lam route at a cost of VND 56 billion.
With confidence in the quality of their work, in October 2022, Son Hai Group sent a document to the Ministry of Transport, committing to a 10-year warranty for the highway constructed by the company.
Son Hai commits to a road surface without cracks or sinkholes, with a flat and smooth surface, including the section connecting to bridges (without bumps when vehicles pass). Under any circumstances of overloaded vehicles, excessive traffic, or adverse weather, the 10-year warranty will not be affected, and the State will not incur any maintenance costs during this period.
Son Hai has requested the Ministry of Transport to publicly display the 10-year warranty signs along the route for the convenience of road users and supervision of the warranty.