Page 8 - TunnelTalk Annual Review 2017

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Bergen, Norway, hosted the successful WTC2017 World Tunnel Congress
HDighlights of the 2017 conference circuit
uring 2017, TunnelTalk attended and the merits and potential drawbacks and Shani Wallis, TunnelTalk was represented at more than 15 concerns of applying TBMs or open face
conference events across the globe. excavation methods for projects where
community relations, occupational health and safety, improvement of productivity through the planning, design and construction phases, and integration of modern and future technologies into the design and management of underground transportation systems.
The vast capital investment currently in underground infrastructure in Australia and New Zealand was described in detail, including:
Sydney: The AUD$12.5-13.5 billion Sydney Metro project for which five new Herrenknecht TBMs will complete 15.5km of twin running tunnels to connect five new underground stations, two mined and three open cut; the AUD$3 billion NorthConnex 9km long twin tube highway tunnel project and the three stages of the AUD$16.8 billion WestConnex highway complex that comprises 22km of twin-tube tunnelling and on which 50 roadheaders are already working on the two stages that are in construction.
Melbourne: The AUD$11 billion Melbourne Metro project that requires 8.4km of twin running tunnels and five new underground stations for which four TBMs and a fleet of roadheaders will be procured, the AUD$5.5 billion West Gate highway project for which two mega-TBMs of 15.6m diameter are ordered with Herrenknecht to excavate the twin 2.8km and 4km tunnels.
Brisbane: The Cross River rail project involves a 5.9km tunnel under the river and central business district plus five new stations to link the city’s northern and southern rail networks.
Perth: Work progresses on the 8km twin running tunnels of the AUD$1.86 billion Forrestfield Airport rail link project on which two Herrenknecht VDM TBMs have launched.
Auckland: Completion of the NZ$1.4 billion 2.4km twin tube Waterview motorway tunnel excavated by a 14.5m Herrenknecht EPBM; early construction works on the Auckland City Rail Link; the new 13km long x 4.5m diameter central interceptor sewer tunnel currently in the procurement stage.
All of the completed, planned and progressing projects are required and inspired by the rapidly increasing population of the cities. In her video recorded welcome address, Gladys Berejiklian, Premier of New South Wales, gave professionals in the room warning that the “pace will not be slowing down. There will be tunnelling to be achieved for many, many years to come.”
Each event presented valuable information to ever growing audiences of engineers and professionals.Lessonslearned,technological developments, revisions of best practices and industry experiences were shared and discussed and reported in TunnelTalk conference articles and videos. The 2018- 2019 schedule will be equally as busy.
Better use of underground space
Optimising the use of underground space within the circumstances of rapidly expanding cities was the conference theme of the fourth annual Arabian Tunnelling Conference (ATC) in Dubai in February 2017.
A keynote presentation by Han Admiraal and Antonia Cornaro, Chair and Vice Chair of the ITA committee on the Use of Underground Space (ITACUS) inspired the delegates to think about other types of underground space developments. “Planners and civil engineers need to work together to realise the potential of the urban underground space and use it to maximum effect,” said Cornaro. “If we don’t expand our thinking towards more creative uses then the space under our cities is a waste of space!” concluded Admiraal.
In reply to a question from the floor that asked: “How can we create public underground spaces without feeling we are in a small or confined environment?” Admiraal replied that it is the interface between the surface and the underground facility that is important. “We must explore methods of introducing more natural daylight and to ensuring that the space and the connecting passageways, and corridors are spacious andaccommodatingratherthanfeelingsmall and over crowded,” he said.
The presentation included a report on the Committee’s Think Deep initiative and the establishment of its Young Professionals Think Deep Programme (YPTDP) that sponsors workshops to investigate the potential contribution of underground solutions to urban problems. After a successful project in Scotland to examine the potential for redevelopment of the Clyde River waterfront for the city of Glasgow, there are developments to organize workshops in several other cities including Dubai which is a city in search of solutions to urban transportation and protection from its harsh summer climate.
TBMs versus open face
A particularly engaging session at the conference was the panel discussion on
either would be suitable.
The debate opened with a call
for standardization of both TBMs and open face excavations to help optimize investment in machinery and reduce the costs of design and construction.
The point was made that on a current road tunnel project in the UAE, three sets of in-situ concrete lining formwork will be obsolete and worthless at the end of the contract as the forms are project specific and highly unlikely to be applicable to any other road tunnel project.
In response, it was explained that all metro running tunnels for different cities in France from 1985 to 2005 were of the same diameter with the same TBMs being moved by contractors from city to city, and that in Norway open face road tunnels are of a standard size – T9.5, T10.5 and T12.
An engineer working on Crossrail underground stations in London described how, for one large underground station, there were initially 20 or so different cross sections. “We managed to reduce these to five standard cross sections but it was a difficult process as there were good arguments for why other cross sections were required.”
Comments of another case study described how open face excavations are often described as ‘conventional tunnelling’, “but there is nothing conventional about the designs put forward,” was the comment. “In one case, the design for a 2m thick heavily reinforced cast in-situ concrete lining was reduced to a 15cm thick unreinforced layer of shotcrete.”
Another question in the debate asked if deciding to place metro and other transportation infrastructure underground is a waste of money? The conclusion, after several contributions, was that no matter the initial budget, or even an over run of cost and time, in the end, the underground infrastructure will become whole heartedly accepted and the woes and troubles of the construction time forgotten.
Terrific regional workload
A concentrated programme of underground space development in Australia and New Zealand was a key focus at the 16th Australasian Tunnelling Conference in Sydney in November 2017. More than 600 delegates from 19 countries appreciated a programme of 129 presentations across the three-day schedule of the triennial event.
Presentations studied important aspects of project development including
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