by Ed Taylor, President, Australasian Tunnelling Society ATS, a technical society of Engineers Australia
In Australia, the recent growth of infrastructure projects that involve the use of the underground space as a part of the solution is a real boost for the local tunnelling industry. There are also many emerging trends and technologies that the underground industry must address in order to find better ways to complete these projects and reap the benefits.
Most of the current projects have been on the radar for many years in the planning phase, with their timing being influenced by political processes and influences. We have also seen what were once surface solutions being driven underground to satisfy community demands.
The number of future projects that almost certainly require a tunnel to enable them to be feasible in our highly developed cities is also quite significant. To avoid hindering these projects from coming to market, it is incumbent on industry to find solutions that are smart, sustainable and environmentally sound. If this philosophy can be adopted appropriately, the outcomes should also be cheaper to build and have lower whole-of-life costs.
Current industry trends
It would seem that Australia prefers to procure its underground projects on the basis that ‘bigger is better’. The trend for even larger infrastructure projects, often driven by the proponents’ preferred PPP delivery arrangement, has both benefits and some downsides.
It is not unusual for these works to have a long planning gestation which is most likely appropriate for the best transport or infrastructure outcome to be achieved. Unfortunately, the delivery of the whole project will almost certainly extend across state or federal political terms and therefore the ‘best planning solution’ may be altered down the track because of short-term drivers.
The market consistently seeks that there be transparency on timing and that they receive bipartisan support to ensure that the financial model and construction teaming can be aligned for certainty of delivery.
To deliver these big projects, large teams are required and are almost certainly all procured by joint ventures with multiple companies and disciplines, each with their differing systems and cultures. It has been shown generally that two party joint ventures work the best, but this has the impact of limiting the maximum project cost to around $3 billion.
To develop a joint venture culture which can deliver outstanding safety and quality outcomes, be environmentally sound, and deliver on time and within budget results, is a big ask. There are several examples of projects that have failed in one or more of these important goals.
There are many other delivery models around the world, many of which are based on numerous smaller contracts delivered by a single entity utilising established streamlined management and delivery systems. However, the Australian tunnelling market, in partnership with many international players, has the ability to deliver quality infrastructure on a larger scale.
Multiple large projects at once
This is the current state of play in Sydney and Melbourne. To put this into perspective, late last year, the suite of Sydney road tunnels saw upwards of 50 road headers operating at once. The introduction of two new metro rail projects and a large diameter machine-bored road tunnel has now introduced over ten new tunnel boring machines, all of which are currently under manufacture.
Despite the number of tier one European and Asian contractors joining the local market, the issue of resourcing is still significant. Appropriately experienced technical staff are already stretched to the limit despite the influx of staff from overseas companies. Almost all of the engineering houses are engaged on one or more projects and quality tunnel design staff are becoming very thin on the ground.
The same also applies to the skilled workforce. We have in recent years seen the establishment of training hubs on major projects to train workers in many of the unique tunnelling skills required. This must grow to full recognition of formal qualifications in tunnelling, with transferability across projects having a positive benefit for both the individuals and employers.
This trend may be seen as good for the economy, but many of the additional overhead costs associated with the resourcing and procurement constraints will become buried in the total community cost of these new projects. This could be alleviated by sensible programming across the states and their infrastructure businesses, levelling out the peaks and troughs, and creating a more streamlined and ongoing sustainable tunnelling market.
There are some interesting developments coming out of the fact that many of our ‘modern’ infrastructure tunnels (generally in the road space) are of an age where operational and performance issues are questioning the original design intent. From a tunnel systems perspective this is understandable as new technology is an ever-developing reality, and a number of tunnels are currently undergoing, or planning, system upgrades in the near future.
The whole traffic mix including electric and driverless vehicles and the use of artificial intelligence as an operational medium will also see the need for fundamental reviews of existing operating systems.
There are also questions being raised against the design philosophy of the primary tunnel structure as, over time, we are gaining a better understanding of the real impact on design life. Are we looking at a realistic tunnel maintenance regime in the longer term? On the positive side, some of our new tunnels are being appropriately specified to address some of these operational deficiencies.
Issues and challenges in the sector
The discussion on trends has highlighted a number of real issues that face our industry now and will continue in to the future. The aspect of operational learning as mentioned before is seen as a real issue because there is no coordinated industry-wide mechanism to appropriately capture the operational knowledge and feedback which needs to flow back into the planning and design process. This is needed to ensure future new infrastructure benefits from what the operators are having to deal with today. Things like design guides and specifications, product and material specifications, construction guidelines and the like all need to benefit from a proper review of operational findings.
Health and well-being
The health and well-being of our tunnel workers must also always be given high consideration in the planning, design, construction and operational phases of an underground project. It has been enlightening to see the workings and outcomes to date from the industry driven Air Quality Working Group in Sydney. This working group brings together clients, regulators, contractors and health professionals from across all current road and rail tunnels under construction in the Sydney basin to focus on the issue of airborne silica and its impact on all underground personnel. The genuine desire by all participating members to come up with real solutions for the benefit of worker health will see some recommendations that may significantly challenge the way we work and manage such projects in the future.
Professional skills shortage
The professional skills shortage within the local tunnel consulting industry has seen, in some cases, a watering down of experience and particularly local knowledge. There are hidden risks here especially where high risk underground solutions are proposed. The influx of experienced practitioners from around the world is clearly necessary and good for the industry, but there needs to be recognition that local environment and ground risks must be truly understood and not underestimated.
Adapting to new technologies
I had the pleasure of chairing a whole afternoon’s session at this year’s World Tunnelling Conference in Dubai, with the session topic being innovation in materials technology. There were several papers on spoil conditioners for use in EPB tunnelling, but the paper I enjoyed the most was on the use of graphene in concrete. The potential benefits in high strength concrete using much less cementitious product has to be good.
Concrete is a major building block in almost all of our infrastructure projects underground, but it is also one of the highest offenders in the production of global warming gases. The sustainability drivers on all new projects can only nibble away at some reduction in the environmental footprint where cement is used. But in saying that, the pressure is there, and the likes of graphene and geopolymer concrete are the sorts of initiatives that could deliver a step-change in concrete technology in the near future.
The growing adoption of 3D modelling in all aspects of concept, design and construction planning is no longer anything new, but the adaption of robotics and artificial intelligence into much of the most risky underground construction activities could make tunnel excavation and support no longer a man-entry process and could leave some of the tunnellers sitting behind a computer screen.
Smart monitoring systems will be essential in making such an activity work, and the same technology, when applied to the monitoring of permanent built assets, should have real benefits in optimising maintenance and planned replacement activities during the operational phase. This is very important in operating transport tunnel environments where any tunnel shut down, with loss of serviceability (revenue in the case of tolled tunnels), can be an extremely expensive exercise.
The time for dreaming is over, there are golden opportunities out there that can reduce the cost of what many see as a very expensive component of an infrastructure asset. We tunnellers must grab those opportunities with both hands and run with them!