Downshire Bridge, The Cut, Banbridge, Co Down, BT32

Downshire Bridge is a single-arch stone and brick road bridge carrying the Scarva–Rathfriland road over the Cut in the centre of Banbridge. Although rebuilt in 1885 in a widened form, it replaces an earlier bridge of 1834 that was part of an ambitious road improvement scheme initiated by the Postmaster General.

The bridge and the Cut together form what is reputedly Ireland's first flyover—a road-over-road crossing. The Cut itself is a two-lane road excavated through the north-facing slope rising from the River Bann in 1831–34 to reduce the gradient along this stretch of the Banbridge–Newry turnpike road. This excavation, some 180 metres long and 15 feet deep, was completed in 1834 at a total cost of £19,000 for the entire scheme including the viaduct and approaches. The work was carried out by William Dargan and financed by the County Down Grand Jury.

The 1885 bridge displays fine quality workmanship. The abutments are of rock-faced blackstone embellished with ashlar granite quoins. The arch is of segmental profile and constructed of granite ashlar, with a dressed granite platband running through it at spring level. The soffit is of purple brick, arranged in five sections that step up by a course from north to south in line with the road gradient—a feature of technical interest. The spandrels comprise randomly sized finely dressed granite blocks with a granite string course at crown level. The parapets consist of replacement vertical steel railings on dwarf rubble blackstone walls coped with oversailing chamfered granite blocks. The parapet walls terminate in ashlar granite piers projecting outwards from just below string course level. On the south-west terminal pier is a polished granite plaque reading "Downshire Bridge / These tablets were inserted by / the inhabitants of Banbridge / to commemorate the coming of age / of the / sixth Marquis of Downshire / 2nd July 1892". On the north-east pier is a second plaque reading "Downshire Bridge / erected AD 1834 / rebuilt 1885". The deck carries two lines of traffic and two footpaths. Modern height warning signs (3.5 metres and 11 feet 6 inches) have been affixed to either side of the arch crown on both faces, and the edge of the arch on both elevations has been painted with alternate yellow and black warning stripes.

The Cut's sides are lined with almost-vertical random rubble blackstone walls which continue up as parapets alongside the roads on either side of the cutting; these parapets are coped with dressed granite blocks. The side walls continue for a short distance at both ends as steel railings on dwarf rubble walls coped with granite flags, which are clearly later additions. The walls are secured with steel plates anchored into their sides.

The bridge was originally known unofficially as 'The Jingler's Bridge'. It was renamed 'Downshire Bridge' in 1892 to commemorate the twenty-first birthday of the town's landlord Arthur Wills John Wellington Trumbull Blundell Hill, sixth Marquis of Downshire (1871–1918). The bridge and Cut are prominently located in the centre of Banbridge town, flanked on either side by two and three-storey historic and modern buildings, now predominantly of commercial use. The former town hall and post office stand immediately to the west.

Nineteenth-century flyovers such as this are rare in Ireland, and the bridge is of historical interest both for its attested date and its industrial archaeological significance as part of a pioneering road improvement scheme.