From the magazine, Microtunnelling, Tunnelling

Breaking ground around the globe


In mid-2010, contractors celebrated a city-wide excavation record on China’s Chengdu Metro, of 475 m in one month.

The 6.26 m diameter Robbins EPB has excavated at rates of up to 24 m per day.

The machine began excavation of Line 2, Lot 18 of the Chengdu Metro in January 2010, as part of a project for the China Railway Construction Corp, Ltd.

Ground consists of a matrix of alluvial geology found nowhere else in China, including highly permeable pebbles, sand, and clay. Crews are utilising foam injection to stabilise running ground, with continuous monitoring of surface subsidence.

Hong Kong

MTR Corporation has awarded Leighton Asia, acting in a joint venture, an $A409 million contract to construct the West Kowloon Terminus Approach Tunnel and Track Fan Tunnel section of the Guangzhou – Shenzhen – Hong Kong Express Rail Link (XRL).

This is the second XRL project contract to be awarded to Leighton Asia, following the award of an $A463 million contract in March 2010 for the construction of tunnels and a ventilation building in the Tse Uk Tsuen to Shek Yam section.

The latest contract includes the construction of a 31 m wide approach tunnel and 121 m wide track fan tunnel. Leighton Asia Managing Director Hamish Tyrwhitt said the company was pleased to be awarded this significant rail contract.

Contract works started in August 2010 with completion scheduled for 2015.


A Robbins 10 m diameter Hybrid EPB machine is making history as the first ever machine of its kind to be assembled onsite, in Madhya Pradesh, India.

The EPB/Single Shield TBM and continuous conveyor system are being assembled using onsite first time assembly (OFTA) – a process developed by Robbins to save both time and money to the contractor.

The machine is being initially assembled in Madhya Pradesh, rather than in a manufacturing facility.

The TBM, for contractor Coastal Projects Ltd. will be launched in early 2011 to excavate the 12 km long Sleemanabad Carrier Canal in highly varied ground including clay, gravel, marble, and jointed rock.


The 15.55 m diameter Herrenknecht Earth Pressure Balance Shield, the largest TBM in the world, will be ready to start work in 2011.

The shield weighs 4,300 tonnes, and has a cutterhead power of 12,000 kilowatts and an overall length of 120 m. It will be completed at the Schwanau plant in southwest Germany.

The machine is set to extend the A1 highway between Bologna and Florence, being constructed as part of the Variante di Valico extension project. This section is planned to accommodate at least three traffic lanes on both sides.

The six to seven lot of new alternate routes include the construction of the Sparvo Tunnel – the profile of which will set a new record in mechanised tunnelling as far as the drilling diameter is concerned. The tunnel will consist of two parallel-running tubes with a length of 2.5 km each.

Toto Costruzioni Generali S.p.A. decided to use mechanised tunnelling technology to improve work safety and to accelerate the works. Toto will carry out the tunnelling works in loose soils with local presence of gas.

In line with the current planning, the machine is expected to start tunnelling near Florence towards the north as early as the first half of 2011.

The six to seven lot is the last section of the Variante di Valico project, and will open, according to schedule, at the end of 2013.


After just under four years of construction, the second Tauern Tunnel in Austria was opened in April 2010. ‰ Õ

The 6.4 km tunnel was mined by Porr Tunnelbau GmbH for ASFINAG, a government-owned company that plans, finances, maintains and tolls the entire Austrian motorway.

The tunnel features seven lay-bys and 26 cross-cuts, 17 of which are accessible – six to emergency vehicles and three to European Union trucks – as well as full cross-ventilation and bright, reflective tunnel wall coating.

Executive Director of ASFINAG Bau Management GmbH Gernot Brandtner said “Spending $A239.2 million, ASFINAG has acquired maximum quality for the construction of the second tube, which is looked upon as a flagship project for future tunnels.”

Following renovation of the twin tubes, the tunnel should be opened to traffic for full operation in late June 2011.


At the beginning of November 2010 the world’s largest hard rock TBM, the 14.4 m diameter Robbins Main Beam TBM, had completed over 8.7 km of the 10.4 km conduit being tunnelled beneath Niagara Falls, Ontario, Canada.

The Niagara Tunnel Project is being undertaken for Ontario Power Generation and will add up to 500 cubic metres per second for hydroelectric generation to the Sir Adam Beck Generating Stations when it is completed.

Geologic conditions have largely determined the project’s advance, from periodic stoppages, to a world record month of
467 m in July 2009.

Project Manager for contractor Strabag AG Ernst Gschnitzer said, “We also raised the tunnel alignment by 45 m to bring the tunnel out of the Queenston shale and into more competent rock, in order to reduce over-break.”

Conditions in the tunnel have been highly variable, with significant over-break occurring within the first 200 m of tunnelling in Queenston shale.

The finished 12.8 m diameter tunnel will be fully lined with 600 mm thick continuously-poured concrete and a polyolefin waterproof membrane to prevent leakage. The tunnel is being lined behind the Robbins TBM using separate invert and arch lining systems as well as a membrane laying machine.

The Niagara Tunnel Project was initiated in June 2004 and is expected to be completed in 2013.


Mexico’s largest TBM, a 10.2 m diameter Robbins EPB, is excavating just 7 m below city streets in a densely urban area of the capital.

Crews are utilising two-liquid back-filling and continuous monitoring to minimise settlement beneath building foundations, roadways, and existing utilities.

The TBM is boring the country’s first new rail route in a decade, the Mexico City Metro Line 12, for contractor Ingenieros Civiles Asociados.

By November 2010, the machine had broken through into its second of seven underground stations after advancing at rates of up to 590 m per month.


At up to 2,000 m below the Andes Mountains, located in Olmos, Peru, crews on the 13.9 km long Olmos Trans-Andean tunnel have successfully faced rock bursting, floods, and fractured ground.

The 5.3 m diameter Robbins Main Beam TBM is excavating highly stressed volcanic rock using a unique method – the McNally Ground Support System, which utilises steel or wood slats to hold back falling rock.

After surmounting a severe rock bursting event, the machine was successfully re-started in August 2010.

Completion of the water transfer tunnel for Odebrecht Peru Ingenieria y Construccion is scheduled in mid-2011.

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