[1] Whitton, a successful railway engineer from England, chose one of Isambard Kingdom 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, with the bottom chords being large iron rods.

[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] The trusses are deck Queen post copied from one of Brunel's Cornish timber bridges (St Germans), built about 30 years earlier.

[1] The Severn River railway bridge was listed on the New South Wales State Heritage Register on 2 April 1999 having satisfied the following criteria.

The timber Queen post deck viaduct was a significant structure in place of the expensive iron lattice bridges preferred by John Whitton.