Hundreds of small-scale timber bridges are now being switched out and replaced with concrete under a NSW government program, which has seen dozens of rural and regional councils spend millions of taxpayers’ dollars on replacing still-functioning hardwood bridges with concrete.
That is according to Chris Swadling, Director of Ironwood Australia, who spoke with Wood Central about Transport NSW’s Fixing Country Bridges Program, allowing 58 councils to apply for funding to replace aging timber bridges in poor condition on council-owned and managed roads.
“At a time when the public wants more timber bridges, councils are actively replacing them,” according to Swadling, who said the $500m program has seen councils, like the Murray River Council, spend thousands of dollars opting for carbon-intensive replacement over timber substitutes Pointing to Taree – on the Mid North Coast – Swadling said that the decision to prioritise concrete replacement over timber maintenance and replacement has led to a farcical situation where residents on the Manning River (impacted by floods) can no longer cross the river. “That decision has added hours to the school run, and the council is still months from replacement.”
As it stands, about 30% of Australia’s 10,000 timber bridges are in poor condition – including 1,800 in NSW alone; however, instead of full timber-to-concrete replacement, the solution could lie in new technologies like stress-laminated timber: “Full replacement can be costly, but engineered timber allows councils to build new bridges and extend the life of existing bridges by decades, at a fraction of the cost,” according to a major timber bridge supplier who attended the International Conference on Timber Bridges in Rotorua, New Zealand.
“Engineered timber gives engineers far more confidence when it comes to measuring loads fators on bridges; which in effect means that we can design new timber bridges to meet the full 100-year design life.”
Why replace bridges when we can repair and restore them instead?
In April, Wood Central spoke with Professor Keith Crews, an international expert in timber bridge construction, who said that better connectors and off-site construction have made timber a compelling alternative to precast concrete in bridge construction: “There are (numerous types of) timber-based technologies that can be used to meet the requirements of the national (AUSTROADS) bridge design code.”
Published in AS 5100.9:2017, Bridge Design, Part 9: Timber, the code outlines the requirements for designing and constructing timber bridges and associated structures, including members with steel connectors, as well as the design of stress-laminated timber (SLT) decks and bridges.
- To learn more about timber bridges, which can be designed to last 200 years or more, click here for Wood Central’s special feature on the Prymont Bridge in Sydney.
