Pneumatic foundations in the bridges of the first Italian railways

In the first half of the 19th century the French geologist Jacques Triger developed a construction process useful for excavating waterlogged soils that applied a caisson to pump compressed air into the working site. His invention was widely deployed in construction engineering, especially for sinking bridge pier foundations in riverbeds. This technology was first used in Italy in the 1850s under the supervision of British and French building companies. It served for the construction of many bridges in the new Italian railway network and resulted from a fruitful collaboration between Italian and foreign technicians.This essay will describe the evolution of cast iron and wrought iron caissons in Italy, a country which provided a favorable environment for the experimentation of this new technology.