Ian Berger

This paper examines the significant role played by opening bridges on the Murray-Darling River system for the passage of river steamers in NSW in the period 1878 to 1925. A number of forms of opening bridges were used during this period, including bascule, swing and vertical lift spans. The latter type was the most common, but within that type there was also developmental variation of design in approach spans and lifting mechanisms. There were three bascule spans bridges built on tributaries of the Murray River (at Darlington Point and Carrathool over the Murrumbidgee River and at Kyalite over the Wakool River); one swing span bridge on the Murrumbidgee River at Hay; and some 11 lift span bridges on the Murray, Darling and Murrumbidgee Rivers, totalling15 opening bridges during the subject period. In all over 50 opening bridges were built by road authorities in NSW to span navigable coastal and inland rivers through to the mid-1960s. Many of these replaced former pontoon bridges, pu...

This paper investigates the strong European influence on timber bridge design and construction in the early Australian colonies. Early bridge building, from circa 1826, comprised very rudimentary round timber beam bridges and with some beautiful masonry arch bridges. This initial period was followed in the mid-19 th century by a much more innovative period of timber arch bridges that were strongly influenced by European and English designs. The period continued until c. 1870 when improvements were made to design detailing and construction techniques of more conventional timber truss bridge designs, based initially on stocky English designs and later on more slender US designs derived from Howe trusses. Whilst only a relatively small number of timber arch bridges were built in the fledgling colonies, it was nevertheless a significant early period of bridge evolution. This review found that, whilst laminated timber arch bridges were an expedient and cost-effective in the short term, they presented maintenance and durability problems in the longer term progressively replaced by more effectively designed large span timber truss, metal or later concrete bridges. Considerable knowledge and artisan skills were acquired during this period in building such large structures, using limited resources other than natural materials and ingenuity. Nevertheless these bridges very admirably fulfilled their intended purpose until traffic loading and volume increased and alternative material costs decreased sufficiently to warrant eventual replacement.