THE LOST HERITAGE OF ROMAN IRON AND STEEL BRIDGES. VIRTUAL RECONSTRUCTION OF TWO CASE STUDIES

In the second half of 19th century the city of Rome knew a period of great urban transformations: the Pope Pio IX and after, the government of the new Kingdom of Italy, strongly pushed the modernization of the ancient and underdeveloped city, trying to follow the examples of the main European capitals. One of the most relevant signs of that period was the construction of multiple iron and steel bridges along the Tiber, that were built to improve the crossing network guaranteed by the old masonry links. Different supporting systems were used and many experimental technologies for the Italian context were tested, representing a crucial phase for the settle of a design and an industrial know-how that was firstly imported from the most advanced countries of the Northern Europe. In the 20th century most of these connections were unfortunately replaced, losing this precious heritage which was strongly linked to the technological culture of the time. Garibaldi Bridge, still present but radically transformed, and Alari Bridge, completely demolished, have been accurately modelled thanks to the availability of appropriate archival documentation and on-site tests, applied following a proposed methodology. The virtual reconstruction of the two case studies permits to spread the knowledge of this lost heritage, to ease the divulgation of past technologies and to recover the unusual image of exposed iron and steel structures surrounded by the ancient panorama of the Eternal city.