Designed by Charles Nixon (a former pupil of I.K. Brunel) and built between 1849 and 1851 by Fox, Henderson and Co, which also built the Crystal Palace in London.
The viaduct is 91 feet high, has four 110 feet spans, each span composed of four cast iron arched ribs, carried on masonry piers 20 feet thick and 30 feet wide. The overall span between end abutments is 500 feet. The 100 feet cast iron ribs were cast on site. When in situ they had transverse diagonal bracing and lattice spandrels that supported a deck of iron plates. These in turn supported the permanent way. The structure was seriously damaged in the Irish Civil War in 1922, but was subsequently repaired. The decking was removed after closure in 1961.