Mostly unseen, culverts allow waterways to flow while acting as a bridge in supporting roads and rail networks. These culverts are now ripe for attention as increasing adverse weather events, along with ageing structures, highlight the essential role they play in regional and metro 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.
Interflow business development manager Stephen McGowan said the taxiway was closed as any potential risk of it collapsing as an aircraft travelled overhead was unacceptable.
“Closing down any critical infrastructure at a major airport has a very high daily cost, and they asked if we could provide a solution, and how quickly could we mobilise,” he said.
“We came up with a solution, verified by our in-house chartered engineers, and had the works completed just weeks after they first approached us.”
Interflow delivered the site works over three days and was awarded the contract on the basis of its competence and their trust in the company’s ability to meet the client’s high standards.
This case study is valuable in demonstrating two important points, one is that culverts can be found in many situations that are vital to the performance and safety of the land and infrastructure around them.
The other is that there are highly effective maintenance and renewal solutions available to asset owners with outcomes that don’t involve the digging of trenches, the closure of roads or runways or requirements of costly and time-consuming stakeholder issues.
Why choose culverts now
Once culverts are installed, they don’t receive a great deal of attention.
McGowan said that has been because of the cost to the organisation responsible for their management and that they don’t attract a revenue stream, unlike wastewater and potable water.
Another is because it was assumed these assets would have a 100-year service life, which McGowan said “is proving wildly incorrect in most cases”.
As a result of factors including increased traffic loads, more frequent major weather events, and assumptions around materials and coatings, many culverts are showing signs of failure in less than half that time.
Some materials in place, such as zinc coated corrugated metal pipes, are deteriorating much earlier that assumed.
For many culvert asset owners in local council, rail, and arterial roads, that’s right about now.
“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,” McGowan said.
“That research is vital to V-Line, which relies on 5000 culverts and 1200 bridges on the Victorian regional rail network, but information contained in the report can also be extrapolated out to other culvert applications.”
Data from this research and other similar studies can be used by infrastructure managers to re-assess the performance life of their own culverts.
Interflow culvert experts regularly discuss such insights with infrastructure managers and can devise trenchless solutions for culverts that are reaching or have gone beyond their end of functional life.
Remote-controlled culvert renewal
The safety of its people is a fundamental component of how Interflow operates. In instances where it’s difficult or dangerous for people to go in, Interflow offers non-person-entry options.
“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.”
For every customer a unique solution is designed after a deep dive into their specific needs and the needs of their stakeholders.
“We have two of Australia’s top pipe rehabilitation thought leaders in our business, with over 65 years of experience between them,” McGowan said.
“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.”
According to McGowan, the company’s experts leave a legacy through their work.
“At Interflow we strive to be the very best at what we do, and in doing so we create better legacy,” he said.
Reducing disruption while shoring up infrastructure
An example of a project that involved innovation, a customised solution that required an enormous level of experience and insight, was one in Victoria, for the Department of Transport and a tier-one civil engineering contractor.
The contractor was responsible for the rehabilitation of 11 bridge structures, one of them had a culvert made up of three cells using RCP pipes that were each 1.8m in diameter. They were a significant size and channelled water under a major high-traffic arterial road.
The culvert pipes, installed in 1992, had begun to fail, threatening the physical security of the road overhead.
The design of the original solution involved diverting traffic and digging up the road to lay new pipes.
Interflow instead recommended a trenchless fix, removing any need for detours and delays for road users and delivered the project in 12 days.
For more information, visit Interflow’s website.
This article featured in the April edition of Trenchless Australasia.
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