13 March 2012
Cranes being used to build Portugal’s Corgo Viaduct are nearing their final height as construction of the tallest piers of the 230m-high crossing progresses.
CAET XXI, a consortium of Soares da Costa, Ramalho Rosa Cobetar and FCC is building the viaduct over the Corgo River in Vila Real. Two Linden Comansa tower cranes are in use for the project and have been hired to Ibergru.
The viaduct, one of the longest and highest in Portugal, is part of the Transmontana Highway, which will link the city of Oporto to the Spanish border.
The Corgo Viaduct will be 2,795m long and have a height of 230m from the valley bottom and a main cable-stayed span of 300m. It will cross three roads and a railway.
The two tallest piers are being built by two Linden Comansa Flat-Top tower cranes of model 21 LC 400, with maximum load capacity of 18t. They are erected with jib lengths of 70m, allowing them to load up to 5,000kg at the jib-end.
The cranes are currently erected with a height under hook of 168m but both of them will soon reach a height of 207m. The jacking-up of the cranes from the initial height of 69.2m has been performed by Ibergru, using a hydraulic cage J4-1 in three phases of up to 101m, 132m and 168m. The final jacking will be carried in the next few weeks to reach the final height of 207m.
In order to ensure the stability of the cranes at such height, each one has four ties to the pier. The tie frames have been installed by Ibergru.
As well as lifting concrete and steel, the cranes have lifted and assembled the framework trolleys, and are also assisting the assembly of the cable sytaysof the bridge.
Project director Luis Nogueiro said that 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 piers with sliding formwork.
The cranes started to work on the construction of the viaduct in October 2010, which is planned to be completed by October 2012.
(There will be a full report on this project in issue 67 of Bridge design & engineering, published May 2012)