Bridge Over North End, London Bridge Station

The bridge over the north end of London Bridge Station is a Grade II listed structure built with six composite cast- and wrought-iron trusses, designed according to James Warren's 1848 patent. It was reconstructed after the original bridge collapsed in 1850 and was built to support an extension to the station forecourt. In 1890, it was converted for pedestrian use. The bridge spans approximately 15 to 21 meters and has a depth of about 1.6 meters, with trusses spaced at approximately 4.2 meters apart beneath a flat-soffit, solid deck made of original cast-iron plates. The trusses consist of individual panels of cast-iron shaped like 60-degree triangles, which are bolted together at the top corners to form the chord. The downward-pointing apexes are pinned to the bottom chord of a wrought-iron flat chain, each measuring approximately 152mm by 3mm (6 inches by 5/8 inch). This bridge is a rare example of a structure made from both cast- and wrought-iron components, showcasing the engineering practices of the 1840s, where the two types of iron were used together. The tendency of cast-iron to fracture led to a preference for wrought-iron in such applications.