Construction began in 1930, in the lull after the War of Independence and the Civil War and when the coffers of the newly independent state, were straining mightily. The reconstruction of architectural treasures such as the Customs House and the Four Courts were a priority. The chief engineer of the Port and Docks Board, Joseph Mallagh, was handed the brief and with Pierce Purcell, consultant, the Liffey’s first reinforced concrete bridge was designed. The central span of just over 34 metres aligns neatly with the Loopline piers downstream for ease of river navigation. The approach spans are 12.2 metres each and the parapets are of Ballyknocken granite. The bridge crosses the Liffey at a slight skew.  http://www.bridgesofdublin.ie/bridges/butt-bridge