With a length of approx. 167 km, National Highway 1 in Cambodia connects the capital of Phnom Penh with the Bavet border crossing to Vietnam. Due to the increasing congestion on this important route, a decision was made to construct the Tsubasa Bridge in Neak Loeung 60 km south-east of Phnom Penh. The structure is a three span stay cable bridge crossing the Mekong River.
The project also included the construction of two 900 m and 675 m long approach bridges. Both structures consist of 35 spans, each of which is 45 m long. The precast concrete girders were fabricated in a construction yard and installed using two sets of erection girders. The precast girders were post-tensioned using Type 12S 15.2 DYWIDAG Strand Tendons, and Type 3S 15.2 DYWIDAG Strand Tendons were used for transverse post-tensioning.
The main bridge is 640 m long and divided into three spans with lengths of 155 m, 330 m and 155 m. The two pylons are 121 m high measured from the pile cap and consist of two individual pillars on the outside of the bridge that are connected by several cross beams. The pylons rest on cast-in-place, 2.5 m Ø concrete piles.
The main girder has a cross-section of 17 m and a height of 1.8 m. The bridge segments adjacent to the pylons were built first so that the stay cables could be installed at both pylons and anchored at the bridge deck.
In total, 930 t stay cables were installed
This way, the stay cables supported the weight of the form traveller during the construction of the bridge sections between the pylons. These were constructed using an underslung form traveller in a 10 day construction cycle. In total, 930 t of Type DG-P61, 55, 37, 31 and 22 DYNA Grip® Stay Cables were installed.
The stay cables are galvanized, waxed and inserted in HDPE ducts. In the main span area, transverse post-tensioning was carried out using 170 t of 32 mm Ø DYWIDAG Bar Tendons. The individual cross beams were stressed using 510 t of Type 12S 15.2 horizontal DYWIDAG Strand Tendons.
Furthermore, 140 t of Type 19S15.2 DYWIDAG Strand Post-Tensioning Systems and 200 t of Types 5S 15.2, 7S 15.2 and 9S 15.2 DYWIDAG Strand Post-Tensioning Systems were used in the pylons. Additionally, 180 t of 36 mm Ø DYWIDAG Bar Tendons were installed in the pylons.
The Tsubasa Bridge is not only a new landmark of the region, but also the longest bridge in Cambodia.