- A new TBM of 17.6m diameter is destined to become the largest machine in the world when its 2015 scheduled launch date arrives. The mega-Mixshield, on order from Herrenknecht by the Dragages Hong Kong-Bouygues Travaux Publics JV as one of two machines reportedly needed for its Tuen Mun-Chek Lap Kok undersea highway link contract in Hong Kong, is marginally larger than the current largest machine in the world, the 17.48m diameter Hitachi Zosen EPBM on the Alaskan Way viaduct replacement highway tunnel project in Seattle. The order pushes the diameter of mega-TBMs ever larger, the technical demand ever greater and the expectation of the current tunnelling industry ever higher.
- In the meantime, Italy has two mega-TBM stories. On the island of Sicily, a 15.08m diameter NFM EPBM is assembled and ready to complete the 3.9km long twin tube highway tunnel for the €392 million contract by the CMC di Ravenna JV. The first mega-TBM used in Italy, for the twin tube Sparvo highway tunnel project, is being offered for a repeat performance on a new project of similar dimensions in either Italy or elsewhere in the world. After completing the two tube 2.5km long highway tunnel, the 15.55m diameter Herrenknecht EPBM system and its experienced operating and management team, was into peak, routine performance when final breakthrough approached, but the €65 million investment was far from amortised on a total 5km of tunnel excavation, and the proven system is offered to a new project's advantage. If reused, it would join other mega-TBM systems that moved from the initial project to another, including the 14.2m diameter Herrenknecht Mixshield that moved to the Lifortovo highway tunnel in Moscow after completing the 4th Elbe River highway tunnel in Hamburg.
- With the news from Hong Kong and notice of other needed revisions, we have updated our tracker of the world's mega TBMs for mid-September 2014.
* = TunnelTalk article - See References below
|2005||Hong Kong||Tuen Mun - Chek Lap Kok
subsea highway link*
|1 Herrenknecht Mixshield||17.6m|
|2015||China||Wuhan Metro road/metro river crossing*||2 Herrenknecht Mixshields||15.76m|
|2013||China||Shouxhiou Lake Highway Tunnel||1 Herrenknecht Mixshield
|2013||Italy||Caltanissetta highway tunnel, Sicily*||1 NFM Technologies||15.08m|
|2011||China||Shanghai West Changjiang Yangtze River Road Tunnel||1 Herrenknecht Mixshield
Ex-Shanghai Changjiang highway tunnel Project
|2013||New Zealand||Waterview highway connection, Auckland*||1 Herrenknecht EPBM||14.41m|
|2011||USA||Alaskan Way highway replacement tunnel*||1 Hitachi Zosen EPBM||17.48m|
|2011||China||Weisan Road Tunnel, Nanjing*||2 IHI/Mitsubishi/CCCC slurry TBMs||14.93m|
|2012||China||Shanghai Hongmei Road||1 Herrenknecht Mixshield||14.93m|
|2011||Italy||A1 Sparvo highway tunnel*||1 Herrenknecht EPBM||15.55m|
|2010||Spain||Seville SE-40 Highway Tunnels*||2 NFM Technologies EPBMs||14.00m|
|2010||China||Hangzhou Qianjiang Under River Tunnel||1 Herrenknecht Mixshield Ex-Shanghai Changjiang highway tunnel Project||15.43m|
|Russia||Orlovsky Tunnel, Saint Petersburg*||1 Herrenknecht Mixshield
Project on hold
|2009||China||Yingbinsan Road Tunnel, Shanghai||1 Mitsubishi EPBM Ex-Bund Tunnel machine||14.27m|
|2008||China||Nanjing Yangtze River Tunnel*||2 Herrenknecht Mixshields||14.93m|
|2007||China||Bund Tunnel, Shanghai||1 Mitsubishi EPBM||14.27m|
|2006||China||Jungong Road Subaqueous Tunnel, Shanghai||1 NFM slurry shield Ex-Groenehart machine||14.87m|
|2006||China||Shanghai Changjiang under river highway tunnel||2 Herrenknecht Mixshields||15.43m|
|2006||Canada||Niagara Water Diversion Tunnel*||1 Robbins hard rock gripper TBM
Rebuilt Manapouri tailrace tunnel machine
|2005||Spain||Madrid Calle 30 Highway Tunnels||2 machines
1 Herrenknecht, 1 Mitsubishi
|2004||Russia||Moscow Silberwald Highway Tunnel||1 Herrenknecht Mixshield
Ex-Elbe project machine
|2004||China||Shangzhong Road Subacqueous Tunnel, Shanghai||1 NFM Technologies
|2004||Japan||Tokyo Metro||1 IHI EPBM||14.18m|
|2001||Russia||Moscow Lefortovo Highway Tunnel||1 Herrenknecht Mixshield
Ex-Elbe project machine
|2000||The Netherlands||Groenehart double-track rail tunnel||1 NFM Technologies||14.87m|
|1997||Germany||Hamburg 4th Elbe River Highway Tunnel||1 Herrenknecht Mixshield||14.2m|
|1994||Japan||Trans Tokyo Bay Highway Tunnel||8 machines
3 Kawasaki, 3 Mitsubishi, 1 Hitachi, 1 IHI
- * TunnelTalk reference below.
Undersea Tuen Mun-Chek Lap Kok highway route
- With the success of mega-TBM tunnel drives of 15-17m diameter and more, it was inevitable that sooner or later a TBM order would be for a multi-mode transportation tunnel. This has happened - for what is believed to be the first time - in China, for a combined three-lane highway and metro crossing of the Yangtze River in the city of Wuhan, and using another major TBM order from Herrenknecht.
- Two 15.76m diameter Herrenknecht Mixshields are ordered by STEC, the Shanghai Tunnel and Engineering Company, for the double-deck, multi-modal transportation link at up to 40m below the water surface under the Yangtze River to create a 2.6km long twin tube six lane river crossing and an extension of the city's Metro Line 7.
NFM mega-TBM launch ready on Sicily
- This is not the first multi-mode tunnel suggestion. In the early 2000s, a similar road and rail crossing of the Hudson River in New York was suggested for urgent replacement of the ageing, deteriorating and seriously overloaded Tappan Zee highway bridge (Fig 1). The New York authority has instead progressed a replacement bridge project, missing an opportunity to clear a blot on the fabulous river vista, improve the environment, and increase property prices - and the associated property tax revenues - for properties on the river banks. The construction of the bridge however has its own challenges with bedrock up to 300ft deep for piled rather than the existing pontoon bridge piers, organized public and environment objection to the bridge project, and reports of a runaway project budget. Could a multi-mode tunnel alternative still yet come from behind to provide the much needed new crossing? The possibilities for the tunnel alternative continue to improve and expand.
- Any discussion of mega-TBM applications must also refer to the world's largest TBM currently that is at a standstill in Seattle awaiting a main bearing replacement.
- The situation for the TBM is not a reason for assigning blame or fault. It is a result of having the courage to advance engineering possibilities and expand existing technological boundaries. There are few tunnel projects around the world that have never been completed. Faced with mechanical or geological adversity, the projects do get finished. The assurance of this, to the industry and its new generations of risk-takers, is that lessons are learned from those who took risks in the past, and that when the project is eventually in operation the memory of cost and time overruns is quickly forgotten as the element of underground infrastructure becomes indispensible and taken for granted.
- That does not excuse the necessary process of investigation and examination of potential negligence or incompetence, but it does warn against moves to stifle innovation and technological advance by overstating the associated risks. The problems, technical failings, and situations that appear to be non-recoverable will be overcome and the tunnel will be completed.
- For all proposed projects that push at existing technological boundaries the industry as a whole must stay united in its support and overall determination to take the possibilities to the next level.
- Join the discussion via the TunnelTalk Feedback facility.
Sparvo mega-TBM system available for new project - TunnelTalk, September 2014
Hong Kong awards major undersea highway - TunnelTalk, September 2013
Mega-TBMs for China double-deck link - TunnelTalk, May 2014
Video: Addressing Bertha's bearing seal issues in Seattle - TunnelCast, February 2014
'Yes' to bored tunnel alternative in Seattle - TunnelTalk, August 2011
Mega-TBM order is NFM's biggest ever - TunnelTalk, January 2013
Mega-EPBM naming ceremony at Hitachi Zosen - TunnelCast, December 2012
New Zealand joins the mega-TBM tunnelling set - TunnelTalk, August 2011
Russia confirms order for largest TBM ever - TunnelTalk, Aug 2011
A second mega-TBM river crossing for Nanjing - TunnelTalk, Aug 2011
Robbins TBM rolls into hard rock history - TunnelTalk, May 2011
Nanjing Highway Tunnels - TunnelTalk, Sept 2009
Seville SE-40 Highway Tunnels - TunnelTalk, April 2010
Giant TBM accepted and heading for Italy - TunnelTalk, Dec 2010
Seattle Alaskan Way bored highway tunnel - TunnelTalk, Oct 2009
UK contributor, name withheld by request
It is hard to say when the era of the mega-machine started. There was a time when 10m in diameter was considered the largest likely, or indeed possible. But whatever was once considered the technological limit for the size of TBMs, there are now many dozens of machines exceeding the 10m diameter size. This, of course, increases the benchmark for current mega-machine criteria. The need for ever-larger diameters is driven by the demand for ever-larger diameter tunnels able to incorporate extra and wider traffic lanes for heavy freight trucks as well as cars. Larger diameter bores are also needed to accommodate the latest in multi-modal transportation tunnels which will house both road and rail services as well as pedestrian and cycle-ways and perhaps also utility corridors.
Discussions in the past have considered the manufacture of the main bearing a limiting factor but these can now be designed and delivered in sections. Precision machining and welding has these vital components of the new mega-machines completed and built into them on site. A limit to the size and load of a single component to job sites was also considered a controlling barrier but first time on-site assembly, as promoted by Robbins in particular, overcomes some of these limitations.
Another consideration, as explained by Yasunori Kondo San at Kawasaki in Japan, is application of the thrust needed to advance such mega machines. For soft ground TBMs this force is applied directly to the precast concrete segments of the tunnel lining. These, as well as the number and size of the thrust rams around the perimeter of the machines, must be designed to take and deliver the powerful forces needed to move a mega-machine forward. There is a controlling factor on the number and power of the thrust rams needed to apply the force, as well as the surface area and ability of the precast concrete lining segments to accept the load.
Other considerations will be explored and added to the Discussion Forum as they are contributed.
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