200-Meter High at the Corgo Viaduct
CAET XXI, a temporary consortium formed by the Portuguese construction companies Soares da Costa, RRC (Ramalho Rosa Cobetar) and the Spanish FCC, is presently building a viaduct over the Corgo river, in the Portuguese town of Vila Real, with the collaboration of two Linden Comansa tower cranes hired to Ibergru, Linden Comansa’s official dealer in the country. This viaduct, one of the longest and highest in Portugal, is part of the Transmontana Highway, which will soon link the city of Oporto to the Spanish border.
The Corgo Viaduct, with a length of 2,795 m, a height from the bottom of the valley of 230 m, and a main span of 300 m, will run over three roads and one railway line. Pillars number 18 and 19, the highest of the whole structure, are being built by two Linden Comansa Flat-Top tower cranes, model 21 LC 400, with maximum load capacity of 18 t, and erected with jib lengths of 70 m, allowing them to load up to 5,000 kg at the jib-end.
The cranes are currently erected with a height under hook of 168 m, but both of them will soon reach an impressive height of 207 m. The jacking-up of the cranes from the initial height (69.2 m) has been performed by Ibergru, using a hydraulic cage J4-1 in three phases (up to 101 m, 132 m and 168 m) and, in a few weeks, the last jacking-up will be carried out to reach its final height of 207 m.
In order to ensure the stability of the cranes at such height, each one holds four ties to the pillar, at heights of 50 m, 81 m, 113 m and 156 m respectively, and with a length from the crane’s mast to the viaduct’s pillar of up to 10 m.
The project of tie frames has also been executed by Ibergru. According to the company’s technical director, António Fonseca, its installation has demanded a strong coordination with the works in progress: “The metal sheets for the ties were set on each pillar by night and during the sliding of the formwork, allowing the sheets to be placed in merely 3 hours.”
Beside the common works of this type of jobsite (hoisting of concrete and iron), the cranes have lifted and assembled the framework trolleys, and are also assisting the assemblage of the suspension cables of the bridge. The tasks comprised by the assembly and disassembly of the supporting platforms located around the pillars due to their position, both large weight and dimensions, were especially complicated to perform.
“The 21 LC 400 tower cranes are matching the high requirements of this type of project, presenting minimal downtime periods while executing simultaneous tasks such as the segments of the deck, the mast and the suspension system and working 24 hours a day while constructing the pillars with sliding formwork,” says Luis Nogueiro, project director.
José Manuel Rio, production director, and Davide Borges, technical department, consider that the usage of these cranes allowed to minimize the number of the risky activities inherent to work at such heights – many heavy large-dimensioned structures have been preassembled on the ground, and then lifted up to the deck level so to avoid assembly works on the top of the pillars.
The cranes started to work on the construction of the viaduct in October 2010, which is planned to be concluded by October 2012. Ibergru has not only rented the cranes, but also contributed with its solid experience in large projects and technical consulting, in order to guarantee that the construction works are completed under the best conditions of both efficiency and safety.
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