Six historic bridges in Bendigo which helped shape the development of the reinforced concrete bridge we know today have been awarded Engineering Heritage Markers.
Although they don’t look much today, these Monier arch bridges were built using reinforced concrete; both the design and material were novel at the time.
The Monier system of construction was patented in 1867 by Joseph Monier, a French manufacturer of garden ware. He used a grid of small-diameter iron bars embedded in a coarse mortar especially for the construction of planter pots. It was only later that the technique and patents were gradually extended to cover, amongst other things, arch bridges
Around the turn of the 20th century, the Bendigo Council decided to clean up Bendigo Creek, which ran through the centre of Bendigo. The creek had been the scene of frantic gold mining activities during the Gold Rush and this left it in dire need of repair to prevent frequent flooding.
The creek was straightened, widened and reformed to run in a formal channel. Existing bridges had to be replaced to span the rebuilt creek.
The Council sought proposals for eight new bridges and after much negotiation the contract between 1901 and 1902 the bridges – of which six still stand and carry traffic – were built in by the Monash & Anderson engineering company, led by General Sir John Monash who went on to be a military commander in World War I.
The gracefully curved design of the Monier bridge transfers some of the weight of the bridge and its traffic to a horizontal force resisted by the abutments, lending it significant strength.
“The Monier arch bridge design has since been superseded by bridges of T-shaped concrete beams, but represent an important ‘stepping stone’ in the development of reinforced concrete bridges. Monier arch bridges took us from masonry and timber bridges to the reinforced concrete bridges we see today,” said Owen Peake, chair of Engineers Australia’s Victorian Heritage Committee.
Originally all eight bridges were designed as wide single arch structures. Following an accident at the King's Bridge in 1901 – when a section of the arch collapsed during the load test, killing contractor Albert Boldt – the bridge was redesigned to have two spans and a central supporting pier, and still stands strong today.
“At the turn of the century when these bridges were built, Australia was undergoing a transformation into a car loving nation. These bridges helped Bendigo and the surrounding area evolve into the city we see today,” Peake said.