The work carried out on theSanta Marta Bridge, located at KP 6+450 of the PO-300 road (T.M. Vilanova deArousa – Ribadumia, Pontevedra) over the Umia River, is detailed. The former bridge crossed the river with an intermediate metal arch with a lower footbridge hanging from it. On April 18, 2023, it was closed to traffic when several ofits suspension profiles broke. After studying the structure, it was concluded that the most appropriate thing to do was to dismantle it and then build a newbridge. To replace it, a Warren-type truss with an isostatic span of 54 metreswas designed. The lower chord is used for pedestrian traffic.

The Santa Marta Bridge is located at KP 6+450 of the PO-300 road (Municipality of Vilanova de Arousa – Ribadumia, Pontevedra), spanning the Umia River.

Span 2 of the existing bridge crosses the river via an intermediate steel arch with a composite deck, featuring a lower steel walkway suspended from it. This span has a length of 60 meters and a width of 10 meters.

On April 18, 2023, the existing bridge was closed to traffic following the detection of damage in several hangers, which caused part of the roadway to sag. No personal injuries were reported as a result of this incident.

To determine the appropriate course of action, the following steps were taken:

• Theoretical study of the bridge’s behavior before and after the incident.
• Visual inspection.

Following these studies, it was concluded that the most suitable solution was the controlled dismantling of the existing bridge and the design of a new one. The state of yielding and corrosion in certain elements made their reinforcement or replacement impossible without an intervention of greater magnitude than the construction of a new bridge.

The project was declared as Emergency Works.

The first action taken was the shoring of the existing structure to prevent its collapse and allow for its controlled dismantling.

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To replace the existing bridge, a Warren truss with a 54-meter span was designed, supported by two piers on both riverbanks.

Lattice pre-slabs (acting as stay-in-place formwork) rest on the two truss planes, upon which the deck slab carrying road traffic is cast. Pedestrian traffic is accommodated within the interior of the truss structure.The truss depth varies between 3.55 and 4.28 meters, measured center-to-center of the chords. It was necessary to raise the landing elevation to clear the frequent river floods.

The scope of work is complemented by on-site Technical Assistance and spot repairs to the approach spans.

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