The evolution of timber truss road bridges in New South Wales

Abstract

This paper explores the development of timber truss road bridges in New South Wales (NSW). In the early 1900s timber bridges were so profuse in NSW that it was widely known by travellers as the 'timber bridge state' of Australia. Timber truss road bridges evolved over at least five distinct stages culminating in the impressive trimmer, more efficient and unique composite designs of the early 1900s. Whilst the English and US influence was strong, there also developed an even stronger colonial 'can do' style. This came about through the need for greater economies, increased vehicle loading, improved materials knowledge, excellent quality Australian hardwoods and Australian-trained engineers, who in turn had a greater appreciation of local conditions. A combination of these factors led to revolutionary ideas in terms of timber bridge truss development, enabling larger, more durable and economic structures to be built. A number of these structures are still in service. Techniques are also discussed as to how some of these bridges have been kept in service, how there is an increasing consciousness of heritage value, how this can be utilised and how this is upheld against contemporary pressures for replacement.