Culverts, which are often unseen, play a critical role in allowing waterways to flow while supporting roads and rail networks. In an era of growing uncertainty and funding challenges, it is increasingly important to recognise their essential role in our infrastructure.
Recently, a major Australian international airport conducted a regular condition assessment of its stormwater assets and found that one of the stormwater pipes running under a taxiway showed some emerging defects. Consequently, the taxiway was closed, as any potential risk of collapse as an aircraft travelled overhead was deemed unacceptable.
“Closing down any critical infrastructure at a major airport has a very high daily cost,” said Interflow Business Development Manager Stephen McGowan. “They asked if we could provide a solution and how quickly could we mobilise. We came up with a solution, verified by our in-house Chartered Engineers, and completed the work just weeks after they first approached us. We delivered the site works over three days and were awarded the contract based on our competence and their trust in our ability to meet the high standards expected of an international airport.”
This case study is valuable in demonstrating two essential points. Firstly, culverts can be found in many situations vital to the performance and safety of the land and infrastructure above and around them. Secondly, advanced and highly effective maintenance and renewal solutions are available to asset owners, with outcomes that don’t involve digging trenches, the closure of roads or runways, or requirements of other costly and time-consuming stakeholder issues.
Why culverts? Why now?
Typically, once culverts are installed, they don’t receive a great deal of attention.
That has been for various reasons, McGowan said. One is because they’re a cost to the organisation responsible for their management. They don’t attract a revenue stream, unlike wastewater and potable water.
Another is that it was assumed these assets would have a 100-year service life. That assumption is proving wildly incorrect in most cases.
Due to factors such as increased traffic loads, more frequent major weather events, and assumptions around materials and coatings, many culverts show signs of failure in less than half that time. Some materials in place, such as zinc-coated corrugated metal pipes, are deteriorating much earlier than assumed, McGowan said.
“For many culvert asset owners in the local council, rail and arterial roads, that’s right about now,” he said. “There’s research initiated by V/Line’s Principal Structures Engineer, Ali Chaboki, that presents findings regarding the remaining life in buried corrugated steel culverts at particular service life stages. That research is vital to V/Line, which relies on 5000 culverts and 1200 bridges on the Victorian regional rail network. But the information in the report can also be extrapolated to other culvert applications.”
Infrastructure managers can use data from this research and similar studies to reassess the performance life of their culverts, ensuring maintenance and renewal work is carried out before major failures impact various stakeholders.
Interflow culvert experts regularly discuss such insights with infrastructure managers and can devise trenchless solutions for culverts that are reaching or have reached the end of their functional life.
Remote-controlled culvert renewal
Interflow’s operation is fundamentally based on the safety of its people. It also offers non-person-entry options when it’s difficult or dangerous for people to go in and do a culvert repair or renewal job.
“That’s something unique that we offer,” McGowan said. “It means that no one has to go into particular culverts, and that’s a major safety improvement. When a culvert is close to collapse, that’s a far better option.”
He said no two culvert projects are ever the same. After a deep dive into each customer’s specific needs and those of their stakeholders, a unique solution is designed for each.
“We have two of Australia’s top pipe rehabilitation thought leaders in our business, with over 65 years of experience between them,” said McGowan. “That’s why I mention comfort and confidence. Every engineer wants to know they’re making the very best choices for the future of the infrastructure they manage. We all leave a legacy through our work. At Interflow, we strive to be the very best at what we do, creating a better legacy.”
Reducing disruption while shoring up infrastructure
An excellent example of a project involving innovation, a deeply customised solution that required enormous experience and insight, was a recent one in Victoria.
“This job was for the Department of Transport and a tier-one civil engineering contractor,” McGowan said. “The contractor was responsible for the rehabilitation of 11 bridge structures. One of them had a culvert of three cells of RCP pipe, each 1.8 metres in diameter. So, they were a significant size and channelled water under a major high-traffic arterial road.”
The water under the bridge was tidally influenced, gushing in and out twice daily. But the culvert pipes, installed in 1992, had begun to fail, threatening the physical security of the road overhead.
The original solution’s design involved diverting traffic and digging up the road to lay new pipes. Interflow recommended a trenchless fix, which would eliminate any need for detours and delays for road users.
“Our solution was to install a temporary coffer dam, which is an isolation dam, and re-line each culvert, one at a time,” McGowan said. “We delivered the project in 12 days and didn’t have to dig up the busy road. It was a completely trenchless solution for a great outcome without disrupting the traffic above. This was an excellent example of doing something innovative in the culvert space to solve customer problems and to minimise disruption for stakeholders, which is very much aligned with our purpose – to improve the lives of the communities we serve for generations to come.”
For more information, visit https://www.interflow.com.au/
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