• Mighty Hitachi TBM tested before delivery to Seattle
DISCUSSION FORUM Tracking the world's mega-TBMs
TunnelTalk reporting
With successful TBM drives proving that bored tunnels of mega dimensions of 15-17m and more in diameter are possible, 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.
 Fig 1. Multi-modal Tappan Zee alternative

Fig 1. Multi-modal Tappan Zee alternative

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.
This expands the list of mega-TBMs, those of more than 14m in diameter, to an impressive record with the application of these tremendous mechanical excavation efforts to all parts of the world but it is not the first time it has been suggested. In the early 2000s, a similar road and rail crossing of the Hudson River in New York was suggested for the urgent replacement of the ageing, deteriorating and seriously overloaded and congested Tappan Zee 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, increase property prices on the river banks (and the associated property tax revenues in return). 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 albeit four tunnel crossing needed to provide a 12 lane line with three lanes in each tube. The possibilities for the tunnel alternative continue to improve and expand.
Let us know if our table needs further updating and we will continue to track the work of these mega machines.
Start date Country Project
* = TunnelTalk article - See References below
TBM manufacturer Diameter
2014 China Wuhan Metro road/metro river crossing* 2 Herrenknecht Mixshields 15.76m
2013 Italy Caltanissetta highway tunnel, Sicily* 1 NFM Technologies 15.08m
2012 China Shanghai West Changjiang Yangtze River Road Tunnel 1 Herrenknecht Mixshield 15.43m
2012 New Zealand Waterview highway connection, Auckland* 1 Herrenknecht EPBM 14.5m
2011 Russia Orlovsky Tunnel, Saint Petersburg* 1 Herrenknecht Mixshield
Engineering started 2009
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
2011 China Hong Mei Road, Shanghai 1 Herrenknecht Mixshield 14.9m
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 Qianjiang Subaqueous Tunnel, Hangzhou
Second tube currently under construction
1 Herrenknecht Mixshield Ex-Shanghai Yangtze River Tunnel machine 15.43m
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 Yangtze River 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
Ex-Groenehart machine
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.
Any discussion of mega TBM applications must refer to the world’s largest TBM ever that is at a standstill with bearing seal trouble in Seattle at the moment. At a quite awesome 17.5m diameter, the giant Hitachi TBM came to a standstill in early 2013 and is unlikely to resume the double deck highway drive before March 2015 as work progresses to sink a rescue shaft, remove the giant cutterhead and gain access to replace the main bearing of the machine and its vital and currently damaged sealing system.
The unfortunate situation for the TBM, for everyone involved, for the project and for the industry at large is no reflection of poor design or manufacturing or poor workmanship or management of the TBM operation. 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 never completed. Faced with mechanical or geological adversity, the project does 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.
Workers dwarfed by a giant 17.48m diameter Hitachi EPBM

Workers dwarfed by a giant 17.48m diameter Hitachi EPBM

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 over stating the associated risks. The problems, technical failings, and situations that appear to be non-recoverable will be overcome and the tunnel will be completed. There are very few tunnel projects around the world that have never been completed with faced with mechanical or geological adversity and the assurance 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 completed and in operation the memory of cost and time overruns (never of lost life) is quickly forgotten as the element of underground infrastructure, despite often vociferous objection ahead of construction, becomes indispensible and taken purely for granted.
For all projects promoted, 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.
Have your say!
Join the discussion via the TunnelTalk Feedback facility.
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.


Add your comment

Thank you for taking the time to share your thoughts and comments. You share in the wider tunnelling community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language professional.
In case of an error submitting Feedback, copy and send the text to Feedback@TunnelTalk.com
Name :

Date :

Email :

Phone No :

   Security Image Refresh
Enter the security code :
No spaces, case-sensitive