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Johann August Röbling (1806-1869) — Early Projects in Context

Kahlow, Andreas

Roebling became acquainted with Navier's theory at the Berlin Bauakademie in 1824/25. During his road planning work in Westphalia, he developed several suspension bridge projects in 1828. Roebling's travels along the Rhein and Ruhr in the winter of 1828 were connected with these projects. Roebling supplemented his notes on Dietlein's bridge-building lectures at the Berlin Bauakademie with excerpts from newer literature on suspension bridges. Under the title "Remarks on Bridge Construction" he discussed the results of his studies. Four known bridge projects can be distinguished. Two are only elaborated as an idea, in one case the project is only known by official letters. Only in the case of the Freienohl Bridge is there an exact description of the project. None of them have been brought to realization. Security considerations of the Berlin Oberbaudeputation probably led to the decision not to execute Roebling's Finnentrop project. This decision ought to be understood within the context of a bridge collapse in Nienburg /Saale in December 1825. When Roebling immigrated to the United States, he used his knowledge in construction methods and experiences with an experimental approach. For this reason, it is interesting to compare the early German projects with his first American bridges. While Roebling's first canal aqueducts combined suspension bridges with trusses, the Niagara Bridge marks a radical step forward to another dimension and to a new approach that emphasized thinking in terms of "systems". Interestingly, he also consistently maintained his construction principle for attaining stability by using rigid, wrapped main cables, inclined stays and wooden trusswork. Although he later used wrought iron profiles, he continued to use wooden constructions in his basic plans for a long time. There is no evidence that he made any contribution to the theories of trusses in a manner comparable with Whipple, Culmann, Gerber or others. Roebling's special talent lay in his constructive gifts.