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By Willow Aliento
October 8, 2018
Major infrastructure projects for underground road and rail are seeing new skills, new technologies, and new business models emerging as part of the tunnelling effort. Many current projects including the Melbourne Metro, the Westgate Tunnel, and the Sydney Metro are also utilising the latest generation of massive Tunnel Boring Machines (TMBs).
Mega tunnel projects have a few major differences from above-ground civil projects or smaller underground endeavours, according to David Grist, Chair of the Victorian Division of the Australian Tunnelling Society.
For a start, the big tunnel projects, such as Melbourne’s Metro, will typically have many more important stakeholders involved.
“This requires a greater effort from both the project owner and the construction team to ensure that the stakeholders are consulted and communicated with. Only this way they are able to deliver a satisfactory outcome,” Grist says.
The projects are often delivered by joint ventures, for example, Sydney’s NorthConnex is being delivered by a joint venture between Lendlease and Bouygues Construction. The projects are generally then procured by a team assembled for the purpose.
“This puts a greater emphasis on the teams to select and train users in business systems practices to be used on the projects,” Grist says.
Subcontractors and consultants brought onto the project may need to understand and adopt systems and software that are different from the ones they are used to. Individuals new to both the client entity and the project team are also often engaged and need to be integrated.
All these factors mean that early in a project’s life, the adoption, communication, and training in the systems and processes are crucial in ensuring the undertaking of a common approach, Grist says.
TBMs have been in use in Australia since Melbourne Water launched the first one in the 1950s. It was used to build part of the sewer network to the Eastern and Western treatment plants.
Grist says that while some aspects of the machines have not changed much, TBMs are becoming more adaptable to different geologies, thus allowing TBM tunnelling in areas which may have not been possible in the past.
Variable density TBMs as well as “hybrid” TBMs are able to be converted from one operating mode to another, which also allows longer and more continuous tunnelling to happen.
Meanwhile, on the ground, there are a number of other new technologies coming into play, particularly in the safety space. According to Grist, they include proximity detection devices which can slow or stop moving plant if it gets close to an individual wearing an RFID or similar tag. Nowadays, these tags are often embedded into PPE, such as helmets or cap lamps.
Automatic location detection is also utilised so that workers are automatically detected entering or leaving an area. “This assists in evacuations to ensure the tunnels and other worksite areas do not have anyone in them.”
Besides serving a role as safety measures, these technologies can also speed up the process of clocking people on and off the site, for example during shift changes.
On any tunnelling job, the program is “crucial”, Grist says.
Compared to an above ground road or rail project, there are also a number of unique systems and design features for tunnels, such as smoke and fire alerts and protection; working with emergency services to provide ingress and egress points for emergency crews; and ensuring refuges for future road users or rail users are compliant with the access stipulations of the Disability Discrimination Act.
Also, because WiFi technologies are not reliable underground, massive amounts of cabling are required for communications, lighting, electrical, traffic management, and fire and smoke safety systems.
“In the big tunnel projects, the commissioning can often involve multiple stakeholders and can be difficult to estimate accurately in a tender,” Grist says.
During the life of the project, he says, as much emphasis is placed on defining the testing and commissioning phases as is placed on monitoring the construction of the tunnels.
While some of the plant and equipment used is covered by existing federal or state licensing rules for operators, a supervisor might undertake a Verification of Competency to ensure people operating some tunnel-specific equipment, such as TBMs are appropriately qualified.
Grist explains that a Verification of Competency can involve the use of virtual reality technology. This way the operator can simulate the operation of a specific item at a site above ground. VR is also used by some of the equipment suppliers as part of the training they provide to project teams procuring their plant items.
During the life of the project as much emphasis is placed on defining the testing and commissioning phases as is placed on monitoring the tunnels' construction, according to Grist.
In terms of training via Australian tertiary institutions, there has been no tunnelling-specific option available. The Victorian Government is changing this, with the announcement of funding for Australia’s first Tunnelling Training Institute at Holmesglen Institute’s Chadstone Campus.
The various certificate and diploma courses are due to have their first intake next year.
Regardless of the lack of domestic courses prior to this, Grist says that as tunnelling is an international occupation. Therefore, when the people cannot be found locally, they can be found internationally.
“A lot of local people have gained experience overseas and will bring that back here,” Grist says. “Experienced overseas people are coming here as well.”
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