Alteration of the span of a railway work without traffic interruption - PS 411 on the Feira/Carvalhos sub-section of the North Highway

The widening of the North Highway to 2x3 lanes, with a future widening to 2x4 lanes, required an intervention in the Overpass that allows the crossing with the Vouga Line, in order to increase the central span from 34 m to 45 m, without interruption of traffic on the motorway or rail.

The existing work consisted of a ribbed deck with three spans, 7.0 m wide, in pre-stressed reinforced concrete, with cylindrical pillars.

The solution developed takes full advantage of the deck and abutments of the existing work, changing it by eliminating the existing pillars, replaced by a new support structure. This new structure is composed of a monolithic prestressed joist with a deck that transfers the intermediate support reaction of the deck to two longitudinal beams also in prestressed reinforced concrete. These beams are implanted at the ends of the consoles of the deck, being supported on two pairs of shafts of elliptical section and fixed to the back of the abutments through definitive anchors in the ground that counterbalance the load applied to the console. to be implanted under the existing deck, therefore with difficult concreting conditions, led to the option of using self-compacting concrete. of deformations that made it possible to slightly raise the old deck, cut the pillars using diamond wire and then slowly and gradually deactivate the hydraulic system, transferring the reaction to the new structure.

It should be noted that the entire construction, including the load transfer operation, was carried out without any interruption of traffic.   

Client:  Brisa, Auto Estradas de Portugal, SA

Project: 2005; Entry into service: 2006