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Josling St. Pedestrian Bridge


Posted: 13th June 2015

Written by: BAC Technologies



Existing timber bridge

In late 2014, the Brisbane City Council (BCC) issued an open tender for proposals for the replacement of the Josling St. Footbridge located within Perrin Park in Toowong. Through routine council inspections of the bridge, it was determined that the existing footbridge was in poor structural condition and required replacement. The contract entailed demolition and removal of all existing bridge components including bridge superstructure, handrails, abutments, and approach paths.


Having been awarded the tender in early 2015, BAC was faced with several obstacles and design considerations which played a major role in the design and installation of the new modular fibre composite bridge. Some of the challenges BAC were faced with included:

-       The presence of Acid Sulfate Soils
-       The sensitivity of working in a Flying Fox roosting area
-       Highly sensitive floodway
-       Extended design life
-       Demolition of existing bridge components



Installation of the micropile system

Acid Sulfate Soils can cause some issues for civil designers as they have the potential to be harmful for the in ground foundation work of bridges. The solution BAC developed was the use of micropiles as the foundation system which involve the use of a grout which is resilient to harsh chemical attack as caused by Acid Sulfate Soils. The micropiles also caused marginal soil disruption during installation given their small, innovative design which minimised not only soils being moved but also significantly reduced onsite work. The presence of Acid Sulfate Soils also posed a challenge during demolition and construction stages onsite as the safe disposal of the soil was critical for environmental protection.

Perrin Park is home to a colony of environmentally protected grey-headed flying foxes that have made roost in the trees lining the banks of Toowong Creek. BAC found a solution to minimise any harm to the local flying foxes as per the Department of Environment and Heritage Protection’s ‘Code of Practice: Ecologically sustainable management of flying fox roosts’. The code suggests that all loud machinery must be started away from the roosts and brought slowly into site, this eliminates any sudden loud noises and lets the flying foxes adjust to the sound as the equipment enters the construction site. BAC also enlisted the services of a wildlife spotter to monitor and report the behaviour of the flying foxes during construction.



Installation of BAC's modular bridge

BAC’s modular fibre composite bridge design was a perfect application for the proposed replacement of the Josling St. pedestrian bridge. BAC’s state of the art resin infusion process was used for the manufacture of the bridge structure here in BAC’s Toowoomba factory while all other onsite work such as demolition and foundation work was underway. The delivery and installation of the modular bridge took less than a day once all abutment work had been completed. BAC’s ‘drop in’ method utilised the bridge superstructures light weight requiring only a single crane to lift the structure onto the awaiting abutments.

The use of fibre composite as the integral bridge structure ensures the bridge will withstand major environmental attack over and above the proposed 100 year design life. Not only has BAC provided the BCC with an excellent value for money bridge system but have also added a very appealing and attractive asset as part of the Perrin Park renewal project.





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