By the end of this year, the capital of Vietnam will have a new road connection between the city centre and the Noi Bai International Airport; the route of the highway, which has four lanes in each direction, crosses the Red River. To minimise obstruction to the 1.2km width of the river, Vietnam’s Ministry of Transportation launched a project to design and build a spectacular cable-stayed bridge and approach viaduct of more than 3km length.

A joint venture formed by Japanese firms IHI Infrastructure Systems and Sumitomo Mitsui Construction is in charge of the construction of the Nhat Tan Bridge, also known as the Vietnam-Japan Friendship Bridge. The main part of the bridge, which is 1.5km long, will feature five A-shaped concrete towers to which the cable stays will be connected.

The construction of these towers, which are located every 300m along the bridge, has been carried out with the help of five 21LC550 18t tower cranes, supplied to Sumitomo Mitsui Construction by Asia-Ted, a Singapore-based dealer of Linden Comansa cranes. The initial assembly of the five cranes, as well as some jacking-up operations, was carried out by a team of Linden Comansa’s technicians, who relocated temporarily from Spain to Hanoi to carry out this sophisticated operation.

All towers are of very similar dimensions, so the cranes were erected with the same settings: jib length of 50m and 11 tower sections, to reach a freestanding height of 63.8m. In addition, each of the cranes was erected on foundations supported on four steel piles driven into the ground, giving the crane an additional height of between 5m and 11m, depending on its location.

The erection of three of the five cranes was especially complicated, as the towers were completely surrounded by the water of the Red River. The lifting of the sections had to be carried out by crawler cranes from barges in the river, which made the manoeuvres more difficult on days when the water was flowing at high speed.

In addition, the need to transport materials and sections on barges required a great deal of planning and slowed down the erection work. While the towers were being built, each one of the cranes had a first tie at a height of 31m, after the sixth tower section, and using an hydraulic cage, each 21LC550 was climbed to a height under hook of 85.8m, or 15 tower sections.

Some months later, they had to be tied for a second time at a height of 60.6m, after the 11th section, and another procedure allowed the cranes to reach a final height of 107.8m, or 19 tower sections. This, combined with the height of the foundations, made the cranes high enough to finish building the towers, which are between 109m and 111m high.

As all of the cranes had the same D33 mast section, which is 2.5m wide, only two hydraulic cages were necessary to perform all of the jack-up procedures, which meant a significant economic saving. The five tower cranes have worked at the job site since 2009. They have lifted all the necessary materials for the construction of the towers, such as formwork, prefabricated rebar cages and concrete.

The cranes also helped unroll and install the cables of the bridge, as well as lifting the cable anchor boxes to the top of the towers. These red pieces of anchor boxes, 29 per tower, were directly embedded into the concrete. They weigh up to 18 tons each, forcing the cranes to employ 100% of their maximum load capacity.

The main steel girders of the bridge deck, which weigh up to 7t apiece, are now being lifted at 50m radius by the 21LC550 from the barge or ground to the bridge deck area. The chosen hoisting mechanism for each of the five cranes at the job site was the optional 65kW, which allows speeds of up to 220m per minute, very suitable for this type of project. In addition, the easy manoeuvrability of the crane and its great precision in locating the load, made construction fast and agile.

During the project execution, the tower cranes were equipped with lights for air navigation, as well as lightning protection to ensure safe working conditions for the staff. The construction of the five towers, and the connection of steel bridge decks between three of the towers has recently finished. The work of jacking-down and dismantling of the cranes has already begun. These tasks, especially the dismantling of the ties, are critical because the cranes are very close to the stay cables, which could be badly damaged by any small impact, requiring repair or replacement of the complete cable.

The Nhat Tan Bridge is on track to open to traffic in October this year after 60 months of construction and completion is due to take place in time for the 60th anniversary of Hanoi Capital Liberation Day.