We begin with the board above the arch on the bridge over the river Tagus. Reservoir of Alcántara. Cáceres.

Once the arch has been closed, the tasks of dismantling and removing the temporary braces have been carried out, and the temporary braces have been dismantled. temporary braces removed the metal pylons demolished over the River Tagus, the Bridge over the River Tagus is ready to proceed with the construction of the to the execution of the section of the deck over the arch, which will mean the completion of the work. Firstly, the piers have been constructed. a40> on top of the arch that will have to support the deck.

Due to the need to make the process as symmetrical and balanced as possible, the deck will be constructed using two self-supporting formwork systems. These are already being assembled on both abutments, to be subsequently moved to their starting position. A less symmetrical construction process would have meant that the arch would have had to be oversized in relation to the service conditions, which is never desirable from both a design and economic optimum point of view.

The greatest challenge in constructing the remaining deck stems from the fact that it must be supported by an arch, which implies a degree of deformability in the supports that does not occur when constructing the deck sections of a standard viaduct. This not only requires enormous control over deformations during construction, but also consideration of the variations in relative stiffness of the system comprising the arch, piers and deck during the different phases of construction.
(Francisco Borja Martín Martínez, engineer at CFCSL).