Mulvin Bridge, (former Railway Bridge), just south of Victoria Bridge, Strabane, Co.Tyrone

Mulvin Bridge is an early 20th-century three-span steel plate girder railway bridge, constructed around 1910–11, spanning the River Mourne in an unspoiled rural setting approximately 1.4 kilometres south-east of Victoria Bridge, near Strabane, County Tyrone. It sits roughly halfway between Strabane and Omagh along what was the 120-kilometre Great Northern Railway (Ireland) line running from Portadown to Londonderry. The bridge and its approaches are enclosed by dense woodland down to the river banks, with open pasture to either side. It has been disused since the closure of this section of line in 1965.

The bridge is the third structure on this site and represents a clear progression of technological advancement in structural engineering. It replaced a cast-iron girder trellis bridge which had itself superseded the original timber crossing built by the Londonderry and Enniskillen Railway around 1850. The current bridge is aligned north–south and carries the former railway — historically known as the GNR(Ireland) 'Derry Road' — over the Mourne River.

Structurally, the bridge consists of two main-span riveted steel plate girders supported on two intermediate stone piers, with a secondary internal plate girder structure carrying the road bed on abutting, contiguous sleepers. The running rails and raised horizontal check rails have been removed, though the support structure for the check rails remains in place. The span is single track in width.

The two intermediate stone piers each have a coping and an intermediate string course. The coping is continuous but is deeper on the east side. The string course on both piers survives along the western two-thirds of each pier but does not continue beyond that point to the east; from this point the stonework also changes character, from coursed rock-faced masonry to uncoursed hammer-dressed ashlar. This indicates that both piers were extended eastward at some stage. The abutments are similarly asymmetrical: although built throughout in rock-faced stone, the western portion of each abutment is flat with a slight batter while the eastern side has a semi-circular projection. Together, these observations suggest that the supporting structure was altered and extended to accommodate a second main span for double track. Tooled ashlar piers are present at the east abutment only, at both ends of the bridge. At the south end, the flat capstone is inscribed 'MULVIN BRIDGE'.

The northern approach to the bridge is level adjacent to the structure, with a cutting beyond it. The southern approach embankment survives, largely hidden in dense undergrowth. The main span is constructed from riveted steel plate girders and latticework. The piers are of coursed rock-faced and uncoursed hammer-faced ashlar basalt, and the abutments are of coursed rock-faced basalt.

The bridge was probably constructed by Alexander Findlay and Company of Motherwell, an engineering firm founded in 1888 that came to specialise in steel bridgework and is recorded as having built the nearby Camus Bridge for the Great Northern Railway at the same time.

The railway's history begins with the Londonderry and Enniskillen Railway Company, incorporated in 1845 and authorised to build a single-track line southwards from Londonderry. Work began soon afterwards and by April 1847 the line had reached Strabane, at a construction cost of approximately £10,000 per mile. However, due to the shortness of the line, storm damage, and competition from the Strabane Canal and Foyle Navigation, this first section was not a great commercial success. It was only with the extension of the line to Omagh in 1852, Fintona in 1853, and Enniskillen in 1854 that the full benefits of the railway became apparent. The line brought important commercial advantages to the towns it served and, indirectly, to the agricultural lands lying along the valleys of the Foyle, its headstreams and tributaries, and to the flanking upland areas to both east and west. Omagh and Strabane in particular emerged as major market centres from which goods could be conveyed northwards to the port of Londonderry.

The Londonderry and Enniskillen Railway was leased to the Dundalk and Enniskillen Railway Company in 1860 for 99 years. That company subsequently became the Irish North Western Railway Company, which was absorbed by the Northern Railway Company on 1 January 1876, which in turn merged with the Ulster Railway Company on 1 April 1876 to form the Great Northern Railway Company (Ireland). The original timber bridges on the line were replaced by cast-iron girder trellis bridges, which were themselves replaced in 1910–11 by the enclosed troughs of riveted steel sheets supported on massive steel girders that survive today at Mulvin, Breen, and Camus bridges. In the post-war period, increasing competition from road transport led to contraction of the network. In 1953 the GNR ceased to exist as a separate and independent company, its entire system being acquired jointly by the Governments of Northern Ireland and the Republic of Ireland and subsequently operated by a board of representatives of both governments. In 1958 the greatly diminished portion of the former Great Northern system within Northern Ireland passed under the absolute control of the Ulster Transport Authority. A period of further contraction followed in which many lines deemed unremunerative were closed, this section ceasing operation in 1965.

Mulvin Bridge has group value with the nearby Camus Bridge and Breen Bridge, which share similar constructional elements. As much physical evidence of the railway line has now been lost, this bridge is a good example of a largely intact steel railway bridge that retains historic authenticity, and it is a rare type, with only five other listed steel railway bridges in Northern Ireland. The townland name Mulvin derives perhaps from the Irish Mullach Fionn or Mail Fionn, meaning 'white summit'; the neighbouring townland of Knockroe derives from the Irish Cnoc Rua, meaning 'red hill'.