After nine months of little visible activity, pile driving has begun on the Rande cable-stayed bridge's two new access viaducts.
The Rande Bridge is a fan-system cable-stayed bridge near Vigo, Spain, spanning the Vigo Ría estuary and linking the municipalities of Redondela and Moaña, around 20km north of the Portuguese border.
The steel-reinforced concrete composite Rande Bridge forms part of the AP-9 Autopista del Atlántico highway that links Portugal’s A-3 highway with the cities of Vigo, Santiago de Compostela, A Coruna and Ferrol in northwest Spain.
Photo: Xunta de Galicia
At the time of opening in 1978 the 1,558m Rande Bridge was the longest cable-stayed bridge of its type in the world. The main bridge is 695m long and 24m wide and is made of three spans of 147m, 401m and 147m. These spans are of the orthotropic type with a reinforced concrete slab. Its four reinforced concrete towers have a height of 148 metres above the estuary.
Two new lanes will carry regional traffic across the estuary between the city of Vigo and the Morrazo Pennisula, thus relieving traffic on the AP-9 stretch of the highway. It is estimated over 50,000 vehicles per day use the current Rande Bridge.
The project involves the construction of two new access viaducts and 706m-long, 5m-wide bridge decks on either side of the existing Rande Bridge. Additional cables on the existing tower portal frames will support the new central bridge decks, which will also be connected to the existing deck with hinged triangular trusses.
Four anchor boxes will be laid on top of the existing towers to accommodate the additional cables that will support the new decks.
The first phase will involve the installation of temporary working platforms in the estuary at the side of the base of each of the four towers, which will then be extended and connected to the towers to support four cranes.
The second phase will involve the transportation of four metal anchor boxes to the temporary platforms by pontoons. These will then lifted using hydraulic jacks along each pylon and then attached on top of the tower portal frames. The first 21m-long steel deck segment will be lifted in the same way and then fixed laterally to the existing deck at regular intervals. Additional bridge sections will be added using mobile cranes that will be set up on adjacent completed sections.
The new access viaducts will be built in the same style as the current bridge using post-tensioned concrete box girders.
Six emergency crossing areas will connect the three bridge decks to facilitate access across the gap between the structures.
The client of the new viaducts is Autopista del Atlantica (Audasa), which has the concession for the 219km AP-9 toll road. The owner is Spain’s Ministry of Development and the contractor is a consortium formed by ACS (Dragados) and Puentes y Calzadas Infraestructuras. The engineers are MC2, part of Typsa, and Manuel Juliá Vilardell, who took part in the construction of the original bridge.
The bridge-widening contract is valued at US$83 million.
Preliminary works began in February this year and the project is expected to be completed in early 2017.