Foundation work of Forth Bridge

This is said to be the original form of the pneumatic caisson method, which was then spread across Europe and introduced into the United States, where the method has evolved independently. The world’s first foundation work using the pneumatic method was the pneumatic pile adopted for a bridge pier foundation near Rochester, U.K., in 1851. From then on, this construction method has evolved into pneumatic caisson, and in the late 19th century, it was adopted for the foundation of the Brooklyn Bridge and St. Louis Bridge in the U.S., the Forth Bridge in the U.K., the Eiffel Tower in Paris (2 among 4 piers facing Seine River), and so on. Then, iron-made caisson was gradually replaced by stone masonry, which had weak tensile force so people stopped using it. Meanwhile, in the U.S. where wood materials are abundant, wooden caisson was used for economic reasons, however, walls bend due to wood drying in compressed air, thus air leaks easily, and stress is unevenly applied during sinking, running the risk of problems and fire. As such, wooden caisson gradually fell into disuse. The pneumatic caisson was adopted also for many skyscrapers that were built in downtown New York in the beginning of the 20th century. Excavation work was fully manual at that time, and there were various issues concerning the work, including decompression disease often occurring due to a lack of knowledge. Furthermore, worker wages at that time were pretty high, reflecting the severe working environment, meaning it was an inefficient and expensive construction method highly dependent on manual work. For reference, measures against decompression disease were first considered around 1910, after more than 1,000 people had suffered from it. However, since there was no construction method for large-scale underground structures, this construction method was actively used in Europe and the U.S. and technological development continued until around 1930s. In Japan, the technology was introduced from the U.S. as part of the earthquake recovery project after the Great Kanto Earthquake in 1923, and it was adopted for new establishment work of the destroyed Eitai Bridge, Kiyosu Bridge, and Kototoi Bridge. Afterwards, development of steel products and construction machines progressed in the U.S. and European countries except for Germany, and when new construction methods such as long and massive steel piles and open caisson were developed, this expensive pneumatic caisson method with severe working conditions came to be disliked, and all at once it almost stopped being used during the 1930s, and this trend has continued. Conversely, in Japan and Germany, pneumatic caisson was steadily used even during World War II. As both countries were in the middle of a hopeless war, they could not afford to assign important resources such as steel materials to anything other than military purposes, especially in Japan, and they didn't have the capabilities to develop new construction methods using lots of steel materials that are superior to pneumatic caisson.

Foundation work of Forth Bridge