Former Railway Viaduct at 10 Knockduff Road Jerrettspass Newry BT35 6LU

Former Railway Viaduct, Jerrettspass, County Down

This is a three-span (originally four-span) semi-circular arched viaduct built of squared stone, dating from 1862–3. It was designed by the noted railway engineer George Willoughby Hemans to carry the former Newry and Armagh Railway over a river that was formerly dammed to form a mill pond, over the driveway to a private dwelling at No. 10 Knockduff Road, and formerly over Knockduff Road itself. The viaduct is located to the west of Jerrettspass, approximately five miles north of Newry, and now sits within the private grounds of No. 10 Knockduff Road, accessed via electric gates. It is now isolated, as the former railway line is no longer extant.

The structure is built of squared, random-coursed, rock-faced stonework, with parapets and retaining walls of the same material. The arches are formed with cut stone voussoirs, and the parapets are finished with cut stone coping. Viewed from the north-east, the left-hand arch spans the driveway, while the two right-hand arches span the former mill dam. A fourth arch, which originally spanned laterally over Knockduff Road, is no longer standing. Only a small section of its pier survives on the opposite side of Knockduff Road, where it is abutted by the modern stone boundary wall of No. 11 Knockduff Road. The deck of the viaduct, which formerly carried the railway line, is now covered in grass.

The viaduct has an interesting constructional history. An earlier bridge of several arches had been built on a slightly different alignment approximately 200 metres to the east during the first phase of works between 1858 and 1860. When the route of the line was revised in the early 1860s, that earlier structure was demolished and its stone reused in the construction of the present viaduct on its current site. A newspaper report from July 1862 describes stone being recovered from the redundant stretch of line, and by December 1863 the completed structure was described as "a fine stone bridge of four arches which spans what once was a mill-dam, together with the public road which runs past it," with the ruins of an old flax mill immediately adjoining to the south, set within what was described as "a deep and most romantic ravine." The old mill, now gone, was in fact located to the east side of the bridge.

The wider history of the Newry and Armagh Railway is closely bound up with this structure. The 21-mile line was originally conceived under an Act of 1845 — on the eve of the Great Famine — as part of an ambitious route between Newry and Enniskillen via Armagh. The first sod was cut on 17th August 1846, but works were suspended in September 1847 due to difficulties in raising funds, with only the earthworks between Newry and Goraghwood completed. The project was relaunched as the Newry and Armagh Railway in 1853, the Enniskillen ambition having been abandoned, and the section between Newry and Goraghwood formally opened on 1st March 1854. George Willoughby Hemans, a Welshman and son of the celebrated poet Felicia Hemans, was engaged to survey the line from Goraghwood to Armagh in October 1856 and served as engineer-in-chief for the construction of this section. Hemans had previously been resident engineer on the Dublin and Drogheda Railway, where he was responsible for erecting the first major wrought-iron lattice girder railway bridge over Dublin's Royal Canal, and had subsequently worked on the Great Southern and Western Railway, the Midland Great Western Railway of Ireland, and several other Irish lines. He was regarded as an innovator in designing railways across bogland and is said to have constructed more railways in Ireland than any other engineer of his era.

The resident (assistant) engineer on the line was Richard Hassard of County Cavan, who had worked as an assistant to Hemans on several other Irish railways. The contractor initially engaged to build the Goraghwood to Armagh section was the Donegal-born William McCormick, working with partners Henry Greene and King of Birkenhead. McCormick had made his name in England organising Irish labourers on railway and public works, and had subsequently worked on the Coleraine and Enniskillen lines in Ireland in the late 1840s. Work began in the closing months of 1858 and was reported as progressing satisfactorily by January 1859, but was suspended again by February 1860 due to lack of funds. McCormick and his partners took no further part in the project. By January 1862 works had resumed under a new contractor, the London firm of John Watson and James Overend, who later worked on the mid-Wales railway. Progress was then being made on the Lissummon tunnel, described as the main difficulty of the line. At the height of construction in early 1863, some 1,500 men were working on the entire section between Goraghwood and Armagh. Many workers were brought over from England, often with their families, and were housed in temporary wooden cottages near the track. Hemans reported in February 1863 that 19 of the 29 bridges between Goraghwood and Markethill were complete or nearly so.

The line from Newry to Armagh finally opened on 25th August 1864. Its construction had been protracted and difficult, and the railway did not subsequently generate the hoped-for revenues. The directors were persuaded to merge with the Great Northern Railway in 1879, the line becoming the Armagh, Newry and Warrenpoint Branch. The line closed in 1957, and by 1974 the northernmost arch of the viaduct had been demolished.

Although the viaduct is of considerable social and industrial archaeological interest, the loss of the fourth arch over Knockduff Road has been judged to reduce its special interest sufficiently that it does not meet the criteria for statutory listing. It is nonetheless considered a good example of a historic structure of local interest.