A major project designed to ease traffic congestion has also provided the Toowoomba community with flood mitigation and improved visual amenity.
What: The Outer Circulating Road Project, which involved the design and construction of a four-lane extension of Victoria Street, a new Gowrie Creek bridge, doubling the Russell Street culvert structure capacity and upgrading West and East Creek channels.
Who: Toowoomba City Council
Why: Initially planned to ease current and forecast congestion in Toowoomba’s CBD
How much: $45 million, with funding from the Queensland State Government through its Royalties for the Regions program
Toowoomba City Council’s Outer Circulating Road (OCR) Project received multiple gongs at the 2015 IPWEA Queensland division conference, named Overall Winner and best Design and Construction Project over $10 million.
OCR principal project manager Angela Fry says the main brief for the project was to provide a four lane extension, in response to a number of traffic studies which had recommended development of an OCR network in the Toowoomba CBD area.
“The Victoria St extension provided the final link in the OCR network which is designed to improve traffic efficiency and reduce congestion in the CBD,” Fry says.
Fry says as the project developed, it became apparent there was also an opportunity to provide significant flood mitigation due to the strategic location of the site.
The project site contains the confluence of West Creek and East Creek which join to become Gowrie Creek (part of the Murray-Darling Rivers system).
The area has had a long history of flooding with records showing devastating floods in 1893, 1906 and 1915 and flash flooding occurring at regular intervals since Toowoomba was established. The area was devastated in the 2011 floods, with significant damage to property and infrastructure and considerable economic loss for businesses and individuals.
Fry says the confluence of the two creeks effectively created a bottleneck where flood waters backed up into streets as the creeks were not able to handle the volume of flood waters.
The OCR project saw the construction of a new three-span bridge over the confluence, a doubling of the Russell Street culvert capacity on West Creek and significant widening and lining of the West and East Creek channels. A covered structure was also constructed over a section of West Creek to help contain water in the channel.
Fry says the project threw up a number of challenges, including contaminated soil.
“The contaminated soil meant considerable excavation was necessary to allow construction of the project,” Fry says. “An efficient truck disposal system was setup to ensure work could continue while contaminated soils were being removed.”
As well as the challenging geotechnical conditions of the contaminated site, the project was constructed at the confluence of two creeks which were prone to flash flooding.
Fry says in order to minimise the potential impacts of flooding, the project team tapped into the council’s Flood Early Warning System to ensure the safety of staff and equipment.
The proximity of the site to two major Toowoomba CBD streets meant that there was considerable social pressure to construct the project under traffic and minimise impacts on businesses and motorists in general.
“Considerable stakeholder engagement with the business and local community before and during construction meant the council was able to mitigate the impacts on residents and businesses while managing expectations,” Fry says.
“The formation of a working group representing area traders meant the speedy resolution of any issues raised.”
Construction on the project began in 2013, with the OCR Victoria Street extension opened to traffic in June 2015.
Fry says the project has been a resounding success.
“The project has garnered overwhelming community and business support while meetings its primary objectives of improving traffic efficiency and flood mitigation,” she says.
“Traffic modelling shows there has been redistribution of traffic throughout the OCR network as a direct result of the project, with an accompanying reduction in CBD congestion. Both East and West Creeks can now contain the nominal 100-year flood capacity within the channels, significantly reducing flooding to the surrounding areas, thus improving safety to surrounding areas during large rain events.
“The project has also had the added benefit of improving the visual amenity of the area, highlighting the iconic Toowoomba railway station."
Fry says since the project opened to traffic in June 2015, adjacent businesses have enjoyed increased patronage to the area, and the project is seen as an economic enabler for future development of the northern CBD.
Held in Mackay in October, the annual Excellence Awards recognise and reward practitioners within local government and public works who achieve innovation and best practice.
Fry also won the Geoff Wilmoth Memorial Award for Best Paper at the IPWEAQ State Conference for her presentation on the OCR.