Ampliación de las luces de 15 pasos superiores continuos postesados, para conseguir el ensanchamiento a seis carriles de la autopista A-7 Barcelona-La Junquera. Tramo: Hostalric-Maçanet

Enlargement of the spans of 15 continuous prestressed concrete overpass to spans at six lanes the A-7 highway Barcelona-La Junquera. Sectio: Hostalric-Maçanet

In order to enlarge the overpasses, each bridge is provided with two steel box romboidal shape girders of strict depth, that rest on the new needed piers sequence. These girders are placed under and at both sides of the transverse cantilevers of the prestressed concrete deck. Through several jacks hanged from the couple of girders, the reactions of the concrete deck on the piers that must be eliminated, were transferred directly to the above mentioned girders. Afterwards, through bars inserted in holes transversely drilled in the concrete deck, a transversal prestressing closes the whole. The jacks were then withdrawn and the ancient piers demolished, leaving the concrete deck in the same initial state without suffering any kind of movement. The whole system remains then prepared to recieve the liveng loading with the new pattern of piers. This new procedure has allowed with maximum security the enlargement of the spans without interfering at any time neither the intense traffic of the highway nor that of the overpasses.