sentences:  The Boyne Viaduct at Drogheda was not built until 1854–55, at a cost of £124,000, to the design of Sir John Macneill, who was the consulting engineer for the D&BJct.The D&BJct line from Drogheda to Portadown connected the Ulster Railway's – – Belfast original line with the Dublin and Drogheda Railway's Dublin Amiens Street – Drogheda line, forming the main line between Dublin and Belfast.In 1875, the D&BJct merged with the Dublin and Drogheda Railway (D&D), forming the Northern Railway of Ireland., which in turn was one the companies that amalgamated to form the Great Northern Railway of Ireland in 1876.