The work carried out on the Mondariz Bridge located on the PO-254 road (T.M. Mondariz – Mondariz Balneario, Pontevedra) over the Xabriña river is detailed. During the Main survey, several pathologies were detected in the structure that forced the traffic to be cut off. After an exhaustive testing campaign and structural modelisation, the repair and reinforcement of those elements that required was designed. All corrosion points were eliminated and the drainage of the structure was improved, extending the life of the bridge.

The Mondariz Bridge is located at PK 8+540 of the PO-254 road (Municipality of Mondariz–Mondariz Balneario, Pontevedra), crossing the Xabriña River. The structure is a 59-metre-span steel bow-string bridge with a total width of 13 metres. It consists of two steel arches with an internal tie.

During the 2020 Principal Inspection, apparently severe damage was observed in some of the main structural elements (hangers, steel box girders, arches, etc.). This damage could imply a reduction in the load-bearing capacity of the structure. The bridge exhibited significant corrosion.

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The works were carried out under an Emergency Works contract and included exhaustive on-site investigations (visual inspection, ultrasonic testing, magnetic particle testing, Brinell hardness tests, macrographic examinations, videoscopy, etc.).
At the same time, a structural assessment of the bridge was performed in order to monitor the stress state of all structural elements.

Based on all this information, the required structural strengthening was designed.
Strengthening, repair or replacement measures were designed for the abutments, neoprene bearings, precast slabs, steel structure (arches, hangers, longitudinal box girders and transverse beams), pavement, vegetation removal and parapets.

All areas requiring intervention were identified, largely due to an advanced state of corrosion. In some cases, the design of additional strengthening plates was required.
For the repair of the hangers, temporary support frames were designed for the existing elements so that the structure was never left in an unstable condition.

Lower scaffolding was installed along the entire length of the structure to carry out underside repairs and painting works. The structure was protected with tarpaulins to prevent environmental contamination and pollution of the riverbed.
The works were complemented by on-site Technical Assistance during construction.