Vietnam's Nhat Tan Bridge sets an Asian record as the longest steel cable-stayed bridge, featuring advanced construction technology

Vietnam’s Nhat Tan Bridge is among the country’s key infrastructure projects, with a total investment of about 13.626 trillion dong. The project broke ground in 2009 and officially opened in 2015.

Project scope and design specifications

The bridge spans 8,930 meters in total, including a main span of 3,755.0 meters with a deck width of 33.2 meters. The main span is a five-tower steel cable-stayed structure with a total length of 1,500 meters, featuring a steel-concrete composite deck on a caisson foundation made with steel pipe rings (SPSP).

The approach viaduct consists of reinforced concrete box girders and Super-T girders. The roadway length is 5,170 meters, with the northern approach width ranging from 70 to 100 meters and the southern approach width at 64 meters.

Interchanges and connectivity

The bridge includes three interchanges. The Vinh Ngoc interchange forms a complete flower-like junction between the main bridge and the extended QL5.

In addition, the project of building the bridge and the two-end approaches officially went into operation, connecting central Hanoi with northern provinces and industrial zones including Bac Thang Long - Van Tri, Dong Anh - Co Loa, and Gia Lâm - Yen Vien. It also helped complete Ring Road 2, shortening the route from the city center to Noi Bai International Airport.

Construction technology and engineering features

According to the Ministry of Transport’s portal, the main span is the longest steel cable-stayed bridge in Vietnam. At the time of opening, it set a record as Asia’s first five-tower steel cable-stayed bridge, a configuration that is normally limited to three towers. The bridge is also described as one of the few multi-span continuous cable-stayed bridges in the world.

Beyond multi-span cable-stayed construction, the main bridge applied several advanced technologies first used in Vietnam, including steel-tensioned anchor boxes on the towers and a monitoring system with devices for measuring cable tension, reinforcing steel strain, and steel girders. A notable feature is the caisson foundation.

Caisson foundation and steel-pipe caisson ring technology

The foundations were built using Japan-developed steel-pipe caisson ring technology, the first time this technology has been applied in Vietnam.

Steel piles for durability and load-bearing capacity

The use of steel piles was selected for durability and strong load-bearing capacity. The method speeds up construction and avoids steps such as sheet-pile cofferdams used in the previous bored-pile approach. While steel-pile costs are higher, the long-term efficiency and economic value are described as better.

The steel piles were imported from Japan, with a diameter of 1.2 m and a length of about 38 m. Construction used a vibro-hammer combined with a high-pressure water jet system to reduce friction, together with a diesel hammer to drive piles to the design depth under suitable geological conditions. This equipment combination was used for the first time in Vietnam.

After driving the caisson ring piles, the contractor dredged river-bed mud inside the ring area and poured concrete to seal the bottom. Steel reinforcement bars were then installed into pier bases, anchor studs were welded to the steel piles to strengthen the connection between piers and piles, and concrete was poured for the pier bases. The tower bases are embedded in the ground, helping preserve the bridge’s aesthetics during dry seasons.

Stay cables and monitoring system

The stay-cable system on cable-stayed bridges typically uses two types: parallel wires (PWS), common in Japan and China, and parallel strands (PPS), common in Europe and the United States. Nhat Tan Bridge uses PWS stay cables, with bundles pre-fabricated and imported to Japanese standards.

During construction, an automated monitoring system continuously supervised the entire construction and operation process, described as a new advancement aimed at ensuring safety and efficient operation.

Assembly process and workforce coordination

The bridge underwent four assembly stages. The final stage of joint assembly was described as a major challenge for the engineering team. After each prior stage, joint stiffness increased, making the final assembly more complex and requiring very high precision. The final joint was completed successfully thanks to the engineers’ expertise and experience.

To build the bridge and approaches, the contractor mobilized over 100 Japanese and Vietnamese engineers. The team worked on-site to collect data, update and analyze information, and directly supervise and guide Vietnamese workers to ensure progress and quality.