FitzGibbon, Abraham Coates (1823–87), railway engineer and antiquary, was born 23 January 1823 at Mount Eagle, Kilworth, Co. Cork, second son of Lt Philip FitzGibbon, RN, and Elizabeth FitzGibbon (née Coates) of Killinure, Co. Wicklow. Educated at the Royal Navy school in London, he was apprenticed in 1873 to Sir Charles Lanyon (qv), who employed him as an assistant engineer. In this capacity he worked on several railway projects, including the construction of the Belfast–Ballymena and Londonderry–Enniskillen lines. In 1847 he joined the company of William Dargan (qv) and worked for five years as one of his principal agents and managers. During this period he completed ten miles of the Dundalk–Enniskillen line, sixty miles of the Dublin–Cork line, and all of the Newry–Portadown line. Commissioned by the Fox Henderson Co. (1852), he went to the USA to survey the entire route of the proposed Illinois Central Railroad, over 700 miles (1,127 km) in length. On the completion of this assignment he remained in the United States and Canada for a further four years, working on railway and harbour engineering projects. In October 1857 he was appointed as principal assistant engineer on the Colombo–Kandy railway in Ceylon (Sri Lanka). This difficult project was suspended in 1860, and shortly afterwards FitzGibbon was engaged by the Dun Mountain Copper Mining Co. to select and survey a railway route in New Zealand. Three years later he was invited to Australia by the government of Queensland and commissioned to survey the routes for the Ipswich, Toowoomba, and Dalby line and the Toowoomba–Warwick line. Requested to prepare estimates for this work, he recommended a 3 ft 6 in. (1.07 m) gauge line in order to reduce costs – the first time that this gauge (subsequently used in several major projects) was used in Queensland. His proposals were accepted in September 1863 and he was appointed as chief engineer of the Queensland railways. Elected a member of the Institution of Civil Engineers (Jan. 1866), he retired two years later and returned to live in England.
FitzGibbon had a keen interest in the history of the Geraldine period in general and the history of the FitzGibbon family in particular. Cooperating with his brother Maurice FitzGibbon, he carried out extensive research among manuscript sources. The two brothers generously funded further research, the results of which, under the general editorship of the Rev. Samuel Hayman (qv), appeared in four volumes as Unpublished Geraldine documents (Dublin, 1870–78), including a piece by FitzGibbon, ‘The sept of the Old Knight’ (1871). He died 4 April 1887 at his English residence, Moorside, Bushey Heath, Hertfordshire.
He married (March 1853) Isabelle Stovin of Kingston-on-Thames, Surrey; they had three sons and two daughters.