Bowstring Bridge | Sado (PT)
The construction of the new Lisbon-Algarda rail connection requires the crossing of the Sado River, which flows into the Atlantic Ocean south of the capital.
The topographical characteristics of this alluvial valley require the construction of two approach viaducts of 1,115 m and 1,140 m and a bowstring bridge, which is a continuous structure consisting of 3 spans of 160 m each.
In each span, the single-girder deck, capable of carrying two rail tracks, is supported by a central arch and vertical metal hangers, giving the whole a bowstring-type behaviour.
The particularity of this structure is in the hexagonal cross-section of the arches and the structural continuity of the deck between the three bridges.
The infrastructure of the complex, which is made of reinforced concrete, is based on piles and equipped with seismic load-absorbing devices.
The height of the piles varies from 4.5 m to 23 m.
SECO’s assignment consists of the technical inspection services of the design of the bowstring bridge and the approach viaducts.
SECO's essential contribution consisted of technical assistance to the client, the provision of technical advice and expertise regarding EUROCODES. Thanks to the fact that the SECO staff includes engineers who are part of the different standardization committees, SECO has a high knowledge of the new EUROCODES and the context for a correct use of these standards. This allows SECO to be able to interpret them correctly and safely, without becoming too conservative.
By reacting very quickly and estimating in advance the risks and possible alternatives, many problems and additional work can be avoided.