Restoration of Pont Trencat: Weathering steel complements stone bridge ruins

Indaten®, ArcelorMittal’s weathering steel, was used to repair the Pont Trencat (Broken Bridge), a medieval stone bridge in the north-east of Spain. The steel arches, in their soft brownish-red colour, complement the exciting stone structure both functionally and aesthetically. After almost 200 years, this broken bridge was given a new life as a footbridge connecting two surrounding villages once again.

Detailed information

Restoration concept: The contrast of new and old

In 1811, during the Napoleonic Wars, the main arch of the Pont Trencat was destroyed. No one tried to repair it for almost one hundred and ninety years until 1996, when people from the two villages the bridge links, Sant Celoni and Santa Maria de Palautordera situated fifty kilometers north-east of Barcelona, created the Associació Pont Romà 2000 in order to raise funds to carry out its restoration.

Archaeological works and document research were first carried out to obtain the information available about the history and the construction sequence of the bridge. Remains of the old arch were found as well as part of the old pavement on both banks. Despite being said to be a Roman bridge - it is placed on the Roman Via Augustea - no remains from that time were found. It was not clear when the existing part had been constructed, but documents were found showing that in 1453 important works were carried out. It is quite likely that the current shape, with its pointed arch, dates from then.

The main issue to be addressed was what action should be taken. As the goal was to recover its functionality "only for pedestrians," the choice had to be made between giving the damaged monument its original shape or rebuilding the missing part in a new form.

It was a difficult decision as both options would be controversial. Since the bridge had been destroyed long time ago, no one knew what it had looked like before it collapsed. An attempt to give the bridge its original shape would have required a great deal of guess work. In addition, people had become used to seeing its broken shape as made clear in its name - Broken Bridge.

Following the ideas of some famous restoration theoreticians such as Austrian Alois Riegl (1858-1905) and Italian Camillo Boito (1835-1914), it was decided that it would be better to reerect the missing part with a modern structure in a way that reflected the contrast between the new work and the existing remains rather than trying to make a mimetic reproduction.

Structural restoration

The structure constructed consists of a two span box girder deck, 3 m in depth, supported by three pairs of bearings - two at both ends and the intermediate one placed over the crown of a hollow box pointed arch, spanning 24 m. To emphasise the old silhouette, the parapets of the deck were extended along the remaining structure. The top line of the new deck and the intrados of the steel arch follow the shape the old bridge was thought to have so that the new structure evokes the missing silhouette of the original bridge.

The work was divided into three phases. In the first phase, the existing remains were consolidated and repaired. Anything that could change its traditional appearance was avoided and, when this wasn't possible (for instance when reinforcing the bottom of the lateral walls), the intervention was highlighted using a completely different material - concrete. A new foundation for the arch on the right bank was constructed.

In the second phase, the abutments of the deck were made: one on the existing remains and the other one on the left bank. The steel structure was constructed seventy kilometres away from the work site and transported in five pieces - three for the deck and two for the arch. First, the two parts of the arch, which were joint welded in the crown, were lifted. For the deck, before it was erected, two of its parts were welded and then installed in two pieces welded to each other on site.

In the third phase, the pavement was made. Over the bridge, a timber pavement was chosen in order to provide pedestrians a warmer and more tactile material in contrast with the coldness of the steel. On both approaches, the pavement was a combination made of rosé granite stone and washed concrete pieces.

The street lighting over the bridge was placed into the parapets of the deck. On the ends, on each side, modern lampposts were installed. The monumental lighting was placed on the lateral slopes, over the maximum flood level.

This design restored the bridge's use, while, on some level, kept the bridge broken.

Project information

  • Sant Celoni and Santa Maria de Palautordera
  • Spain
  • Architect:
    Xavier Font Solà
  • 2003
  • Client:
    Ayuntamiento de Sant Celoni, Ayuntamiento de Santa Maria de Palautordera, Associació Pont Romà 2000
  • Engineering Firm:
    Xavier Font Solà, Enginyer de camins, canals i ports. Alfa Polaris S.L.
  • Contractor:
  • Photographer:
    Xavier Font Solà
  • Text:
    Xavier Font Solà