Heritage and conservation register

As a timber truss road bridge, it has strong associations with the expansion of the road network and economic activity throughout NSW, and Harvey Dare, the designer of this type of truss.

Dare trusses were fifth in the five stage design evolution of NSW timber truss road bridges. They were similar to Allan trusses, but contain improvements which make them stronger and easier to maintain. This engineering enhancement represents a significant evolution of the design of timber truss bridges, and gives Dare trusses some technical significance.

The Scabbing Flat bridge has iron piers, which is a rare technical and aesthetic feature, and has the ability to demonstrate much about the manufacturing technology of the early 20th century.

In 1998 there were 27 surviving Dare trusses in NSW of the 40 built, and 82 timber truss road bridges survive from the over 400 built.

The Scabbing Flat bridge is a representative example of Dare timber truss road bridges, and is assessed as being Regionally significant, primarily on the basis of its technical and historical significance.

The timber trusses are supported by painted cast iron twin cylindrical piers. The approach spans are supported by timber trestles. The bridge deck provides a single lane carriage way with a minimum width of 4.5m. A timber post and rail guard rail extends the full length of the bridge.

Timber truss road bridges have played a significant role in the expansion and improvement of the NSW road network. Prior to the bridges being built, river crossings were often dangerous in times of rain, which caused bulk freight movement to be prohibitively expensive for most agricultural and mining produce. Only the high priced wool clip of the time was able to carry the costs and inconvenience imposed by the generally inadequate river crossings that often existed prior to the trusses construction.

Timber truss bridges were preferred by the Public Works Department from the mid 19th to the early 20th century because they were relatively cheap to construct, and used mostly local materials. The financially troubled governments of the day applied pressure to the Public Works Department to produce as much road and bridge work for as little cost as possible, using local materials. This condition effectively prohibited the use of iron and steel, as these, prior to the construction of the steel works at Newcastle in the early 20th century, had to be imported from England.

Harvey Dare, the designer of Dare truss and other bridges, was a leading engineer in the Public Works Department, and a prominent figure in early 20th century NSW.

Timber truss bridges, and timber bridges generally were so common that NSW was known to travellers as the "timber bridge state".