Tenterfield Creek railway bridge, Sunnyside

When John Whitton, Engineer-in-Chief for Railways 1856–1890, extended the Main North railway line from Muswellbrook to Glen Innes, 1870–1884 it climbed through the highest parts of the Great Dividing Range into the New England Region. Gradients were steep, curves were sharp, there was heavy earthworks and some major iron lattice bridges. It was expensive railway construction.[1]

So when the section from Glen Innes to Tenterfield was planned, economies were made, particularly with bridges. They had to be timber, mostly ballast top timber beam bridges but at three locations larger bridges were required, over Beardy Waters, Severn and Bluff rivers.[1]

Whitton, a successful railway engineer from England, chose one of the famous I. K. Brunel's timber bridge viaducts built in Cornwall during the 1850s. The model chosen was the St Germans Viaduct composed of composite deck Queen post trusses, the bottom chords were large iron rods. Whitton's staff redesigned the trusses to be all timber and the viaducts were built during construction of the Glen Innes to Tenterfield section 1884-86.[1]

The final section to Wallangarra, 1888, was mostly easier over plateau country but the crossing of Tenterfield Creek required a large bridge and a timber Queen post truss viaduct was built there also, the fourth between Glen Innes and the Queensland border.[1]

Only two other such timber viaducts were built in this period, on the Bombala railway line over Ingalara Creek and the Bredbo River, see separate inventories.[1]

Former railways chief David Hill called the old Great Northern line that first linked Sydney and Brisbane the most important stretch of heritage track in the country.[1]

The Queenslander reached Wallangarra with their line in 1887. The NSW line came north from Tenterfield in 1888, but because the two systems used different track gauges, passengers had to change trains at Wallangarra's unique railway station.[1]

In 1930 a standard gauge track was completed all the way to Brisbane via Kyogle and the Great Northern Railway started to go into decline. The last passenger services went north to Wallangarra in 1972 and to Tenterfield, 20 kilometres (12 mi) further south, in 1989. These days the New South Wales section of the line runs from Sydney - Armidale.[2][1]

Bridge in poor repair, 2015

The single 4 ft 8+1⁄2 in (1,435 mm) standard gauge railway bridge is located 784.233 kilometres (487.300 mi) from Central Sydney railway station or 12 kilometres (7.5 mi) north of Tenterfield. The six-span timber truss viaduct bridge has a 12-metre (40 ft) span centre to centre of timber trestles. The Queen post trusses are deck Queen post copied from one of I. K. Brunel's Cornish timber bridges, the one called St Germans viaduct, built about 30 years earlier.[1]

As at 4 April 2006, the timber Queen post truss viaduct was an economic bridge for the Glen Innes to Wallangarra Railway at a time when the boom years of the 1880s was ending and funding for railway construction was decreasing. Despite a degree of inaccessibility, the timber viaducts over the Beardy, Severn and Bluff rivers are impressive structures within their rural landscapes. At Tenterfield the adjacent New England Highway provides easy viewing of the forth such viaduct. There are also two more on the Bombala railway line.[1]

The Main North Railway made a significant contribution to the development of the New England Region from the time of its construction 1882–88, and the four timber viaducts were important items of the railway's infrastructure. The timber Queen post deck viaduct was a significant structure in place of the expensive iron lattice bridges preferred by John Whitton. The viaducts were technically sound and durable, having been built from renowned ironbark hardwood. They are a unique class of railway bridge.[1]

The Sunnyside rail bridge over Tenterfield Creek was listed on the New South Wales State Heritage Register on 2 April 1999 having satisfied the following criteria.[1]

The place is important in demonstrating the course, or pattern, of cultural or natural history in New South Wales.

The timber Queen post truss viaduct was an economic bridge for the Glen Innes to Wallangarra Railway at a time when the boom years of the 1880s was ending and funding for railway construction was decreasing.[1]

The place has a strong or special association with a person, or group of persons, of importance of cultural or natural history of New South Wales's history.

This item is assessed as historically significant due to its association with the early expansion of the NSW railways to colonial borders during John Whitton's tenure as Engineer-in-Chief.[1]

The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales.

Despite a degree of inaccessibility, the timber viaducts over the Beardy, Severn and Bluff Rivers are impressive structures within their rural landscapes. At Tenterfield, the adjacent New England Highway provides easy viewing of the fourth such viaduct.[1]

The place has a strong or special association with a particular community or cultural group in New South Wales for social, cultural or spiritual reasons.

The Main North Railway made a significant contribution to the development of the New England Region from the time of its construction 1882–88, and the four timber viaducts were important items of the railway's infrastructure.[1]

The place has potential to yield information that will contribute to an understanding of the cultural or natural history of New South Wales.

The timber Queen post deck viaduct was a significant structure in place of the expensive iron lattice bridges preferred by John Whitton. The viaducts were technically sound and durable, having been built from renowned ironbark hardwood.[1]

The place possesses uncommon, rare or endangered aspects of the cultural or natural history of New South Wales.

Sunnyside is one of four viaducts and the two on the Bombala railway line are the only ones of their type built. They are a unique class of railway bridge.[1]

• Sunnyside railway station, New South Wales
• List of railway bridges in New South Wales

Media related to Sunnyside rail bridge at Wikimedia Commons