The story of the transformation of a structure: from arch bridge to…

The acquaintance of the constructive rules to assume in the recovery operations, often disregarded, should represent the cultural background in order to properly face operation of preservation and transformation. To this aim the case of Druso bridge is wanted to be introduced. The bridge was planned and realized in the first years thirty from the engineer Eugenio Miozzi, managing of the state roads division of the province of Belluno, Bolzano and Trento, and the engineer Gilberto Ricci. The designers, for this 3 arches bridge in reinforced concrete, covered with rose porphyry, planned a particular sagacity, the “systematic cracks”, based on the use of compensating joints. Miozzi improved then the technique, so that it was adopted in subsequent projects, such as the bridge of the Barefoot ones in Venice. The Druso bridge has been an experimentation that has affected the planning of the arch bridges, one of the many intuitions that confirm the technical talent of the Miozzi. The procedure of “stylistic washing” used in the seventies besides modifying the design has also altered the structural conception. In fact, all the elements, such as parapet and statues, curved out of stone from Vittorio Morelli, have been removed. As the method has been immediately criticized from the population, in the nineties the need to widen the bridge has required a new project. The street centre has been increased arranging the parapet and some ornamental elements similar to the original ones. The history of the bridge becomes therefore a good example to make us comprise that the improvement and therefore the preservation of the built enviromnental cannot be based just on formal parameters, but also on the technological ones.