Bailey truss

Sir Donald Coleman Bailey (1901-1985) was a civil engineer from Yorkshire who invented the Bailey Bridge. He studied at The Leys School in Cambridge and at Sheffield University. He was knighted in 1946 in recognition of his bridge design. Bailey was a modeler, and presented a model of his temporary bridge design to his superiors in the British War Office, who saw some potential for his idea. The prototype Bailey Bridge was assembled in 1943 and remains in place today. The Bailey Bridge uses prefabricated, modular, rectangular panels that can be carried by 6 men and transported in military 3-ton trucks and do not require cranes for assembly. There are components that allow for panels to be "ganged" next to each other (up to three wide) and stacked double tall allowing the same pieces to be used for a light, short bridge or a long, heavy load bridge. The first military installation occurred in Italy in 1943, and production was ramped up for use during and after D-Day.

The US Army licensed the bridge design and began to use it during the war. Postwar, surplus Bailey Bridge components were sold for private and public use. Several examples of extant Bailey Bridges are shown below.

The main component of a Bailey truss is the panel that is (measured pin center to pin center) 10 ft long by 4 ft 9 inch tall [3.05 m by 1.45 m]. There are three verticals and two "square" diagonal braces in each panel. Other components are stringers, bracing frames, end posts, etc.

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Although it is common to call any prefab modular bridge a Bailey, there are actually a number of companies making similar modular bridge components. Some of the bridges in this (Bailey) category might actually be other types. The US DOT has published a guide to the different types of modular prefab spans here: http://www.fhwa.dot.gov/bridge/prefab/psbsreport03.cfm

For bridges built with pre-fabricated modular steel panels but are not actually a Bailey truss, see the category "Pre-fab, modular steel panel truss".