Thu Thiem 2 cable-stayed bridge

The idea for the bridge was born on the return flight from Toronto to Helsinki. Bridge chief designer Antti Karjalainen browsed through the airline’s magazine after the conference. A photo of a “dragon’s jawbone” inspired the design of the bridge and WSP in Finland won the bridge competition in Vietnam in 2010 based on the idea inspired by it. The project perfectly represents WSP’s versatility: WSP’s bridge, architecture, design and lighting experts from Helsinki and Oulu participated in the design of the winning proposal, and the end result is a proof of good teamwork.

After the competition, WSP’s team continued to take part in all design phases of the Build & Transfer project format: general, structural and construction-time design, including e.g., the design of the geometry of the cantilever installation and the engineering drawings of the steel structure. 

The bridge’s backward sloping and curved pylon is distinctive and forms a unique landmark in Ho Chi Minh City. Despite its unusual shape, the structural design of the bridge is optimal.

The 200-meter main span of the asymmetric cable-stayed bridge is a lightweight composite structure of steel and concrete, and the 115-meter back span is a concrete structure. With this solution, the structure has been brought into balance so that there are no bending stresses in the pylon due to permanent loads. The structure has also been optimized with the position of the angled cables of the back span.

In accordance with WSP’s Future Ready approach, the bridge has been created to last at least 100 years and high-quality and long-lasting materials and equipment have been chosen for it. The high quality is also emphasized by the stainless-steel cladding of the bridge’s edges, which at the same time improves the wind properties. The effects of climate change were taken into account in the design phase, which can be seen on site as rise in the water level, extreme wind conditions and erosion caused by water flow occur.

The bridge received an honourable mention in the RIL Competition (Finnish Association of Civil Engineers) in November 2022.

The project has provided several young Finnish designers the opportunity to develop their skills in an export project, and at the same time the training carried out in Vietnam has promoted the development of the skills of both our own local experts and our partners and the modernization of construction projects.

The structural calculations of the bridge contain hundreds of construction stages. As a specialty, 3D geometry transfer based on open data transfer (IFC) has been used between calculations, site measurements and workshop manufacturing of steel structures. From the structural calculations, the precambered manufacturing form of the steel structures was transferred to modelling (BIM) in IFC format. This way, the dimensions and shape of the steel structure were obtained very precisely and the construction went particularly well.

The project was the first BIM pilot project in Vietnam. In the project, Finnish information modelling guidelines were introduced and the project’s personnel was trained in the use of a new technology. Vietnam is a very traditional environment and understanding and utilizing digitization became a great value in the project. The instructions and practices translated into Vietnamese have been taken as the basis for further national development.

WSP in Finland has worked on bridge projects in Vietnam for over 20 years and previous projects have included the Binh and Rao 2 cable-stayed bridges in Haiphong and Tran Thi Ly in Danang, and the Cao Lanh highway project with its numerous bridges.

The chief designer and team leader of the Thu Thiem 2 bridge was the export director Antti Karjalainen who works in Ho Chi Minh City in Vietnam. His team last won the Hue city bridge design competition in the region in 2021. The general plan for this 180-meter main span arch bridge was completed in June 2022.