Der Bau eiserner Brücken im Südwesten Deutschlands 1844 bis 1889 - Vom Gitterträger zum Fachwerk (Teil 3)

The construction of iron bridges in the southwest of Germany from 1844 to 1889 - from lattice girders to truss girders (part 3).

Between 1856 and 1858, Bros. Benckiser, a company from Pforzheim in Germany, had built several lattice girder bridges for Switzerland's railway companies. In contrast to developments in Prussia, they were built as continuous beams without joints, spanning three to four bays. Benckiser used this structural feature for the construction process of the bridges and optimized it that way. The box girder was prefabricated as lattice girder at one abutment side and pushed on rollers and lifting mechanisms, cantilevering at the intermediate supports, into its final position.
With this construction process, which is known today as Incremental Launching Method and used primarily in concrete bridge building, Benckiser Bros. constructed two cross-boundary railway bridges between 1859 and 1860: the Rhine bridges Waldshut-Koblenz and Kehl-Strassburg. It was not until 1860 that the company adopted truss girders with single or multiple bracing for steel bridges with parallel or curved chords.