Aggiornamenti tecnologici per l'Acquedotto Storico di Genova: il caso del ponte sifone sul Geirato

The siphon bridge over the Geirato is an extraordinary architectural, engineering and hydraulic work from the late 18th century, part of Genoa's historic aqueduct system, whose design and construction took more than a century, involving scientists and famous architects of the calibre of Luigi Vanvitelli and Carlo Barabino. The siphon bridge has undergone continuous modifications and upgrades to improve its efficiency and keep it in line with the changing needs of the city. This contribution aims to investigate, through images and documents, the adjustments that the siphon bridge has undergone over time: from the installation of a new set of cast iron pipes in the first half of the 19th century, to the replacement of individual elements, highlighting the historical transition form wedges to threaded bolts, to the pioneering water purification system in the 1950s. The latter took place after the aqueduct had already been decommissioned, in order to remedy the declaration of non-potability of the water issued by the Prefect of Genoa in 1917 and to supply water to the small village of Molassana Alta using the old loading tank of the siphon itself. The siphon bridge over the Geirato still defines the profile of the valley of the same name and, thanks to volunteer associations, it is possible to visit it and appreciate part of its complexity.