Once considered an unfashionable civil engineering solution, a series of colossal multibillion dollar tunnelling projects is changing the way Australia thinks about infrastructure.
Tunelling has long been associated with European know-how, with vast rail projects carved through mountainous terrain, or high-tech societies such as Singapore, where complex underground systems have enabled urban high density.
Yet Australia’s tunnel engineering expertise is now being recognised globally, along with pioneering innovations that have arisen from the sophisticated local mining industry and unique conditions.
As the populations of the country’s major cities continue to grow, so too does the demand for efficient transportation systems, water management and utilities.
By some estimates, Australia is in the midst of an infrastructure boom the likes of which has not been seen since the 1980s.
Tunnelling has come a long way since then and meets community expectations in terms of sending traffic and resources underground, minimising disruption to existing infrastructure and preserving valuable above-ground real estate.
Consequently, major tunnelling projects have boomed in recent years, with a surge in investment and technological advancements leading to bigger and more complex operations.
In terms of scale alone, in the 1980s, there were only about 90 projects worldwide with an excavation width span between 15 m and 20 m, whereas today, tunnels regularly go up to 30 m.
Better safety standards and the development of new materials and construction methods have also allowed engineers to build tunnels in a wider range of environments, including underwater and in geologically challenging terrain.
Significant Australian projects currently underway include the Melbourne Metro and West Gate Tunnel in Victoria; WestConnex, Sydney Metro and Snowy 2.0 in New South Wales; and Cross River Rail in Queensland.
Major new tunnels are also being planned, such as the North-South Corridor in Adelaide, the Greater Western Highway in the Blue Mountains and the Inland Rail Tunnels in South-East Queensland.
With this appetite for state-of-the-art infrastructure not expected to slow down any time soon, tunnelling is set to play an increasingly important role in shaping Australia’s future.
To appreciate how far we’ve come — and to learn about the opportunities and challenges in this exciting field — create sat down with a number of leading Australian tunnelling engineers.
A proud history
“Australia has a long and proud history of tunnelling, even before the Snowy Mountains Scheme,” said Aurecon engineer Dr Harry Asche, the head of the Australian Tunnelling Society.
“There was, however, a time in the ’70s and ’80s, which was the freeway age, when population density hadn’t grown to the extent it has now. By the end of the 1980s, a resistance developed to putting freeways through suburbs, and tunnels became more popular again in Australian cities.”
In recent years, Asche said, the resurgence in tunnelling for new railway lines, roads and sewers has been seen particularly in Sydney, Melbourne and Brisbane.
He is currently working on Sydney’s Western Harbour Tunnel, which is using the largest tunnel boring machine in Australia to connect the city’s Inner West with its northern suburbs.
“Around 40 years ago I commenced my career on a project with essentially the same alignment called the second Sydney Harbour crossing, which ultimately failed for political reasons,” he said.
“That tunnel was 10 km across, which at the time was considered way too long; now we have WestConnex, which, when joined up, is over 20 km long.
“The other issue was that the ability to build a tunnel in mixed ground with soft material and water under the harbour was not really feasible back then with the tunnel boring machines we had.”
Asche explained that Australians played a significant role in the revolution that is tunnel boring machines, with local engineer David Sugden helping to perfect the disc-cutting technology that is used in all of today’s big rock machines.
“The first working rock tunnel boring machine in the world was actually in Tasmania,” Asche said.
“It set records that just blew everyone’s mind, doing more than 200 m in a week — well beyond what anyone else had ever done.”
Asche believes that one thing in Australia’s favour is that there is no “Australian method” of tunnelling. Instead, the country’s engineers have sourced the best innovations from around the world.
“All of the vehicles are less polluting than they used to be, and the ventilation and fire requirements are better understood,” he said.
“Road safety technology is much better than it used to be in a 10 km long tunnel and, of course, the tunnel excavation and safety of doing that is much more versatile than it used to be.”
Asche maintains that tunnel projects make cities more resilient, sustainable and capable of decarbonising — and new methods of automation are something that will only make the process better.
But he added that there is little worry about ChatGPT being asked to start drawing up plans for major infrastructure programs and putting engineers out of work, with automation used largely as a safety feature.
“I recently visited the West Gate Tunnel project in Melbourne that I worked on the design of, and it was really interesting to see how many precast, prefabricated items are being used in the tunnel construction,” Asche said. “A lot of manual labour is being taken out, which makes it safer and cheaper, without taking away from the skill of people who are working on it.”
Safety innovations
Australian experts highlight that the improvements in tunnelling safety play a key role alongside technological advances.
Pells Sullivan Meynink (PSM)’s principal geotechnical engineer Robert Bertuzzi CPEng labels the industry’s view on health and safety of staff and workers — and the community in general — the biggest change he’s witnessed over 30 years in the tunnelling industry.
“No one works under unsupported ground, and that’s an innovation that came from Australia’s mining industry — and it’s fairly unusual compared to most other countries,” he told create.
While the modern era of tunnelling is widely regarded as having begun in the 1970s, it was the Australian innovation of the permit-to-tunnel (PTT) system, which commenced about 15 years ago, that has been a game changer.
“The PTT said that every 24 hours, or every time we excavate the face, we get in the geotechnical engineer, the tunnelling engineer and the construction team together to review the conditions and the ground behaviour and confirm that there is a design to cater for those conditions and that it’s safe to proceed,” said Bertuzzi.
“It’s a big improvement.” Australia continues to pioneer the PTT system globally and has tried to introduce it into other jurisdictions.
“The industry recognised that the design is under construction, and we don’t have complete knowledge of what the ground will look like until you excavate it,” said Bertuzzi.
“Even the best geotechnical model, taking into account a reasonable range of conditions, can turn up surprises when you get to excavating.”
He said that the level of engineering done in Australia is to an exceptional standard.
“The comments I receive from international engineers is that we exceed in the detail and other considerations when it comes to the actual engineering of the problem.”
However, Bertuzzi has reservations about the increasing amounts of paperwork involved in Australian tunnelling and is concerned that the benefits of the PTT could be lost if this paperwork continues to become attached to the system.
“We could do better in terms of bureaucracy, where projects have become more contractually onerous,” he said.
“There is a place for them, but we’ve got management plans that cover design, dust control, air quality, water quality, noise, spoil management — and the list goes on. “These documents can be 50 or 60 pages each, which is a phenomenal burden. Foreign construction companies come in and get caught out, because they’re not aware of just how much paperwork is required to operate in Australia.”
Bertuzzi doesn’t want Australia’s culture of tunnelling innovation to suffer, especially given that much of it has been driven by the desire to remove people from unsafe areas.
On this front, he notes that many companies now use laser or optical scanning to get the excavated profile, which is useful for surveying and quantifying the amount of materials that have been used, as well as for geological mapping.
“We have developed equipment to be able to remotely install rock bolts and shotcrete and, I’m sure in the next few years, tunnellers will adopt the mining approach of more remotely operated equipment, such as roadheaders and tunnel boring machines,” he said.
“One innovation that PSM has designed is handlebar plates, which are a structural connection between the shotcrete lining and the rock bolts. It’s particular to our tunnelling environment where our permanent lining is often installed at the face.”
The moderately strong rock that typically underlies the major cities of Australia’s east coast means that there is high stress for their relatively shallow tunnels.
“Because we are designing for civil applications, we cannot accept any kind of cracking or signs of failure,” he said.
“We’ve come up with ways to counteract that through stress relieving slots, void formers in our lining to accommodate subsequent displacements [and] we monitor the displacement through endoscope cameras in the boreholes, which are all innovations particular to Australia.”
Shoring up talent
Elena Gavazzi, an associate principal at Arup, began her career in the United Kingdom before moving to Australia three years ago to work on the Melbourne Metro — a massive engineering project that involves navigating design and construction, space constraints, building in a busy environment, and having to deal with multiple stakeholders, subcontractors and supply chains.
“Once it’s open, Melbourne Metro will showcase Australia’s expertise in terms of building tunnels,” she told create.
“It’s a highly innovative project, creating a cathedral-sized tunnel underneath Melbourne. The only time this has been done before is in Moscow, Russia.
“The design and construction advancement that has gone into building means that, apart from the acoustic sheds, you wouldn’t know something is going on underneath.”
Gavazzi notes that Europe has seen something of a downturn in its major works projects, but the growth and evolution of Australia’s major cities has meant a lot of tunnelling projects are currently under way — and that it’s an exciting time to be working in engineering here.
Australia’s significant mining history means there is expertise that can be translated into all major infrastructure projects,” she said. “From an engineering perspective, one of the biggest challenges is actually servicing the amount of work with the skills that are out there, and that skills shortage includes construction and other specialists.
“Fire engineers are particularly difficult to find on the market to service these major projects.”
Fire safety is a key consideration for both construction and operation of a tunnel, with emergency evacuation and egress schemes required to be in place from start to finish.
“Covid had a big impact on a migration workforce coming to Australia to fill the skills shortage,” Gavazzi said.
“We also need to be looking at our young graduates and universities to see how we can better help with upskilling and get them interested in the tunnelling industry.”
Gavazzi is part of the Australian Tunnelling Society committee, which is engaging with universities by looking at their programs and seeing how to get students involved with initiatives such as the Victorian Tunnelling Centre, a specialist state government–funded training school for workers involved in the construction and operation of a variety of tunnels.
“Everybody needs to be on board when it comes to upskilling graduates, from universities to industry to contractors and consultants — it cannot be just one party,” she added.
“When someone takes a course, they need to be supported in understanding the opportunities and how their career can progress in the field.”
The industry is also working on a number of initiatives with universities, including organising site visits and talks with different companies involved in design, building and constructing Australia’s biggest infrastructure projects.
“Attracting talent from different backgrounds is also important — you don’t see a career if [you] don’t see somebody else that looks like you out there,” Gavazzi said, acknowledging that she wants to help tunnelling become less of a “blokey” industry.
“Forefronting examples of engineers from diverse backgrounds will help more young people see a future in our field.”
Sustainable tunnelling
University of Queensland geotechnical engineer Dr Jurij Karlovsek is similarly passionate about educating and preparing a new generation of engineers to lead major projects.
One way to help attract young workers to the field is to highlight a renewed push on the sustainability of tunnelling, which has not always been considered “green”.
“The tunnel industry is increasingly shifting its focus towards sustainability and environmental responsibility,” Karlovsek said. “A key question we are asking is how tunnelling can support urbanisation while simultaneously reducing the environmental impact in a heavy construction industry.”
Karlovsek said that the creation of underground assets in urban environments has been made possible with tunnelling. A significant amount of material — specifically concrete — is invested in creating these spaces, tunnelling remains an essential tool for urbanisation.
“As a representative of Australia at the International Tunnelling Association, I am proud to announce our initiative to develop sustainability indexing in the tunnelling industry,” he said.
“This indexing aims to highlight the value that tunnelling provides sustainable urbanisation.
“We are focusing on achieving a more sustainable vision for our planet and working with the United Nations to promote these indexing efforts globally.”
While digital technology has enabled the philosophy of sustainable indexing in tunnelling, Karlovsek added that the industry now has access to information modelling and data analytics tools that allow it to measure and monitor projects and assets more effectively, helping to focus on the value of tunnel development in urban areas.
“Despite its relatively small population, Australia is renowned for leading innovation, with expertise in supporting significant projects worldwide,” he said.
“The tunnelling industry is a global market, with companies competing and tendering for the same global projects.” Several Australian universities, including the University of Wollongong, the University of Technology Sydney, the University of Newcastle and the University of Queensland have established research centres and courses for underground development and technologies.
“However, industry support is crucial for these activities to be effective,” Karlovsek said. “With increasing difficulties in bringing in overseas talent for large projects, more industry support is necessary for universities to work effectively in this space.”
He believes that the Australian Tunnelling Society’s young members group is already increasing diversity in the society.
With its international counterpart at the International Tunnelling Association, which now has representatives from over 30 member nations, the society is opening up conversations across borders.