The Miguel Torga Bridge crosses the Douro Valley at a height of 90m in a hilly area with large rocky outcrops and of great natural richness, next to Régua, intersecting also the railway line of the Douro and two national roads. The bridge is 900m long and 25.70m wide and the alignment is curved in plan and in elevation. The deck is a continuous prestressed concrete, single-cell box-girder of variable height cross-section. It has 11 spans and the span over the river is 180m long.
The webs are 60cm thick, with the exception of the 180m span and the two adjacent spans, which have a thickness of 70cm. The webs are interconnected by slabs and by crossbeams 5m apart. In addition to the longitudinal prestress, the deck’s upper slab and upper crossbeams are also prestressed. All prestress is adherent. Reservations for eventual future reinforcement (external and grouted prestress) were included.
The bridge was entirely cast “in-situ” using the balanced cantilever method in 5m segments.
The shaft of the tubular piers has a constant cross-section. In the tallest ones, four ribs of variable size provide the necessary widening and stiffness towards the base.
The deck is supported by piers P1 to P6 on pot-bearings and it is monolithic with the remaining four.
Foundations are laid directly and almost superficially on granite and schist formations.
The Miguel Torga Bridge was completed in 1997 and was awarded the Engineering Prize in the 1st Ibero-American Biennial of Engineering and Architecture for its innovation and technical difficulty.