American Bridge, Saint Petersburg

About

The American Bridge (also referred to as The Howe Bridges, or Nikolaev Railway Bridge until 31 December 2008) is essentially a group of railway bridges that connect the Bezymyannyi island (St. Petersburg) to the left bank of the Neva River via the Obvodny Canal, and provide links between the Central and Nevsky districts of the city of Saint Petersburg. The wooden bridges of the same design as now were constructed over the period 1840-1850 during the construction of the Nikolayevskaya Railway. The main construction works were supervised by the prominent American railroad engineer George W. Whistler to a design by William Howe, an American bridge builder and inventor. The essence of this construction project was that the bridge spans were a truss system (which was very new) consisting of timber support systems delimited by steel crossbars. The presence of metal components made the bridge structure much stronger without significantly increasing the overall weight. The William Howe's system was theoretically checked and then improved by the Russian engineer Dmitrii Juravsky, who was an executive assistant to George W. Whistler during the construction of the railway line. Juravsky performed structural analyses and tests on physical models of Howe trusses from 1843 to 1848, and executed studies of the effect of posttension in Howe trusses. He published two books "About Bridges of the Howe System" in 1855 and 1856. Juravsky was able to prove that the closer to a bridge's pillars, the greater the strain on the vertical tension bars and diagonal braces. So, he proposed to make the truss members of varying thickness depending on a specific location. His ideas were endorsed by Whistler, and then used in the construction of other rail bridges on this line. As the road was built in the forward direction, it was necessary to build 278 artificial structures.

Adapted from Wikipedia (CC BY-SA). Photography via Wikimedia Commons.