Tunnel Boring Machines, History and Trends in Canada D. Ifrim HMM, Mississauga, Ontario, Canada D. Zoldy URS, Richmond Hill, Ontario, Canada

ABSTRACT In the past two centuries several industry pioneers efforts have made mechanized underground excavation more efficient. Among those famous names are Sir Marc Isambard Brunel, Henri-Joseph Maus, Charles Wilson, Joseph Hobson, James S Robbins, Dick Robbins, and Richard Lovat who shines as the Canadian icon of tunnelling. This paper discusses the history and evolution of the modern Tunnel Boring Machine (TBM), trends and new developments in the Canadian industry. The paper focuses on developments of mechanized tunnel boring machine technology. This paper included review of significant Projects and TBMs that have been built over the last 40 years, for the Canadian market. 1. INTRODUCTION “Tunnelling by its nature offered only a tiny working area, with a rock face not much larger than a bed sheet and about the same amount of room to stand in. Only a handful of people could labour within it at any one time, and much of every shift was wasted wrestling tools and work product out of one another’s way” (Hapgood 2004)

During the industrialization era of the 19th century, among other industries, tunnelling developed rapidly, main driver being the need of developing the railway network. In hard rock, tunnelling beginnings were in drill and blasting. Following the need to mechanize the drilling process the first developments were seen in creating more efficient drills. Some attempts for excavating the rock completely by machines were also made.

2. THE INDUSTRY PIONEERS The history of the development of the first Tunnel Boring Machines (TBMs) contains many attempts, which failed due to various problems mostly related to the technological limits and available materials.

2.1 The Early Years The first successful tunnelling shield was developed by the French-English engineer Sir Marc Isambard Brunel to excavate the Thames Tunnel. The project began in 1825 and due to lack of funds was completed in 1842. The tunnel opened to traffic in 1843. Brunel had been knighted in 1841 for his engineering achievement.

Brunel’s invention was not a complete TBM, but rather a shielded excavation concept, digging still being accomplished by standard excavation methods.

The first boring machine reported to have been built was in 1846 by Henri-Joseph Maus, and was nicknamed “Henri-Joseph Maus’ Mountain Slicer”. The machine was commissioned by the King of Sardinia in 1845 to dig the first rail road connecting France and through the Alps.

The machine was built in a military factory in 1846 nearby Turin, Italy. The Revolution of 1848 affected the funding of the project, and the tunnel was not completed until 10 years later, by using less innovative and less expensive pneumatic drills. “(Hapgood, 2004)”

The boring machine consisted of more than 100 percussion drills mounted in the front of a locomotive-sized machine, mechanically power-driven from the entrance of the tunnel.

Figure 1. The Mountain Slicer sketch by Henry-Joseph Maus, (from Hapgood 2004)

The massive power required to drive the mountain slicer would be generated outside the tunnel and carried to the work face via mechanical linkages. The further the tunnel proceeded, the more of these linkages would have been needed, and the more power would’ve been lost in transmission. It seemed inevitable that the slicer would eventually stall out. Although non-functional, the machine was viewed more like a piece of engineering art and definitely a step in the direction of what was to come later, in the development of the modern TBM.

2.2 The United States

In the United States, the first boring machine to have been built was used in 1853 during the construction of the Hoosac Tunnel. Made of cast iron, it was known as Wilson’s Patented Stone-Cutting Machine, after inventor Charles Wilson. The system drilled 10 feet into the rock before breaking down. The tunnel was ultimately completed more than 20 years later, by conventional methods. (Maidl, Schmid, Ritz, and Herrenknecht, 2008).

About 193 lives were lost during construction, leading to the nickname of "The Bloody Pit." The Hoosac Tunnel included the first commercial use of nitroglycerin in the United States. Some lives were lost due to the unstable nature of nitroglycerin, but many more were lost to the even more unstable black powder, which was used before the nitroglycerin was introduced. (HoosacTunnel.net)

The first successful attempt to use mechanized tunnelling was on the Oahe Dam in South Dakota, US in 1952 by James S Robbins (The Robbins Company 2012)

Figure 2. The First Successful TBM (from The Robbins Company) 2.2.1 Canada In Canada, the first mechanized tunnel construction was the St. Clair Tunnel, built between 1888 and 1890. In October 1884, the Grand Trunk Railway hired the St. Clair Frontier Tunnel Company as a Canadian corporation to construct the tunnel and Grand Trunk Railway appointed Canadian engineer Joseph Hobson in charge of the project.

After making two failed attempts to construct the tunnel by traditional means, in 1888 Joseph Hobson had successfully combined three innovative techniques for the first time in the construction of a large-size subaqueous tunnel: Tunneling shields, Cast iron tunnel lining and Compressed air work environment.

2.3 Pioneer TBM Manufacturers with work in Canada

2.3.1 The Lovat Inc Company

Lovat Inc. (LOVAT) was the first and remains the only Canadian TBM manufacturer to date. LOVAT activity

dates from 1963, when Richard Lovat founded the company named “Richard’s Machinery and Repair Ltd.” The company started by providing repairs to heavy equipment and fabricate custom tunnelling equipment. Shortly after, Richard Lovat developed various ideas for boring equipment, and established his own technology for Tunnel Boring Machines.

In the very first year of operation, the company built the first Tunnel Boring Machine (TBM) for a sewer project in Welland, ON. (TAC, 2000)

In 1972 the company changed its name to “Lovat Tunnel Equipment Inc.”

The first TBM to be fabricated under the LOVAT name was the fifteenth TBM built.

In 1974 LOVAT built the first TBM for the international market, for Catania, Italy. The TBM was the seventh machine built under the LOVAT name. Since inception LOVAT built over 250 TBMs for more than 700 tunneling projects worldwide.

Figure 3. LOVAT 250th TBM (from Lovat Inc.)

Throughout the years Richard Lovat developed and

patented numerous methods of increasing productivity, and maximizing safety for tunnel workers such as a ripper assembly, a rib expander, a device for erecting a segment tunnel wall lining and a head intake for tunnelling machines.

Figure 4. Launching of TBM at the Moscow Escalator Project (from Lovat Inc.)

In 2007-2008 LOVAT developed a TBM capable to tunnel at an incline of 30

0 to be utilized at mechanized

excavation of the deep Moscow Subway Escalators. Beside the special working conditions due to the steep incline the engineers at LOVAT had to deal with the project requirement for the TBM retrieval. Special tooling and equipment was developed to allow for the TBM disassembly inside the tunnel and safe removal. A special consideration was given to maintaining the tunnel support during TBM retrieval; solutions included sacrificial skins and grouting. The site engineers, technicians and the Contractor site staff showed great skills in completing the disassembly and removal of the TBM in a safe mode.

Some of the most outstanding achievements are listed in Table 1.

Table 1. LOVAT reference achievements

Year Country Project Details

1974 US 3961825 Patent for Tunnel Machine

1977 US 4010676 Patent for Rib Expander

1986 US 4732427 Patent for Head intake for tunnelling machine

1987 UK Thames Water Ring Main

Lovat manufactured its first EPB TBM, 3.6m DIA for tunnelling 4.5km without intermediate shafts at 6.5 bar

1993 Canada / US

St. Clair River Tunnel

EPB TBM, with a diameter of 9,530 mm to excavate 1884m tunnel under the St. Clair River

2008 Canada TTC Developed the Owner Procurement Process for TBMs

2009 Russia Moscow Escalator Tunnels

11 m diameter EPB TBM to excavate several tunnels at 30 degree decline

2.4 The Robbins Company The Robbins Company (Robbins) was the first to supply TBMs for work in Canada with the Robbins Main Beam TBM supplied for Humber River sewer tunnel in Toronto in 1957.

Robbins designed and built the world’s first working TBM for the Oahe Dam diversion project near Pierre, South Dakota, USA, shortly after the company’s founding by James Robbins in 1952.

Robbins major breakthrough in the design of the hard rock TBMs came in 1956 with the development of the first Beam Machine equipped with Disc Cutters. The TBM was used in the Humber River tunnel in Toronto, ON.

Robbins also developed and built the first Double Shield TBM, in collaboration and based on the concept introduced by Dr. Carlo Grandori in 1972( (Maidl, Schmid, Ritz, and Herrenknecht, 2008).

Table 2. The Robbins Company reference achievements

Year Country Project Details

1953 USA Oahe Dam First rock TBM

1957 Canada Humber River First successful use of disc cutters

1977 Italy Orichella First Double Shield TBM

1

2006 Canada Niagara Hydroelectric Power Project

World largest Beam TBM

1The contractor for the project, SELI, needed a TBM solution

that would protect workers in broken ground and provide a rapid rate of advance, while simultaneously lining the tunnel. To fit their need, The Robbins Company developed Dr. Grandori concept to construct the first Double Shield TBM.

3. CANADIAN TUNNELS Unlike other mountainous countries such as Switzerland or Norway and despite its size, Canada is not distinguished by well-known rail or road tunnels. It is possible to travel from sea to sea, from Halifax to Vancouver, by CN Rail, without going through any major tunnels, merely a few short ones.

There are, however, some notable tunnels in Canada, for utilities and even transportation that are unique. Some of these tunnels, built by TBMs or other methods, will be discussed in this paper.

3.1 Western Canada 3.1.1 Mount Macdonald Tunnel The Mount Macdonald Tunnel supplements the nearby Connaught Tunnel that the CPR opened in 1916. Construction commenced in 1984, and the first train passed through in 1988. At 14.7 km, the Mount Macdonald tunnel is the longest railway tunnel in the Americas.

The tunnel includes a section of 8353m of round top heading constructed by a TBM. The section employed a Robbins TBM model 222-183.

Figure 5. Top Benching - Key hole method (from Knight, 1987)

The TBM tunnel works were affected by a sealing system and then Main Bearing failure due to overload while mining in extremely hard marble and quartzite (30,000 to 40,000 psi).

Despite the 10 weeks delay the work continued at a fast pace achieving an average of 23.3m a day (average penetration rate of 2.62m/hr) and a peak daily rate of 63m and a weekly high rate of 250m in a 5 day week (Knight, 1987).The TBM completed the tunnel on schedule breaking through on June 1986.

The tunnel features the first use in North America of a concrete “Pact-Track” floor system, eliminating the need for wooden railway ties and crushed rock ballast, greatly reducing maintenance costs.

3.1.2 Edmonton LRT Tunnels Among many TBM driven tunnels in Alberta and Edmonton in particular, Edmonton LRT distinguish itself by size and significance. The tunnel, 5.4m in diameter, was the first LRT tunnel in Canada.

The project employed a Lovat TBM, Owner procured. The first project included a total of 470 metres of TBM bored tunnel with Ribs and Lagging as primary support in sandy clay soils.

The first tunnel was constructed on Jasper Ave. between 101 St. to 107 St. The tunnel construction started in 1976 and completed in 1977 in preparation for the 1978 Commonwealth games.

Several other tunnels were completed with the same TBM in 1981 and 1982.

City of Edmonton has developed a unique approach for tunnelling, by developing a tunnel construction group. The group operates and maintains a number of TBMs purchased along the time to construct its own tunnels for sewers and water mains.

3.1.3 Canada Line LRT project, Vancouver, BC The tunnel project represented the critical path on Vancouver's 19km long Canada Line rapid transit construction program. The tunnel is a twin bore 2.45km long, and extends through the downtown area. The project was constructed by SELI-SNC Lavalin joint venture.

Figure 6. Canada Line Breakthrough, (from Lovat Inc.)

The project employed a 6 metre Lovat EPB TBM, to construct a 5.3 metre segmental lined tunnel.

The TBM arrived on site in May 2006 and completed the tunnels in March 2008.

For the most part the TBM has operated in EPB mode under pressures ranging from 0.6 bar to 2.6 bar. Settlement readings along the route have been negligible - mostly less than 4mm and a maximum of less than 7mm. The TBM averaged a steady rate of 18 rings a day.

3.1.4 Evergreen LRT Line, Vancouver, BC The project links the cities of Burnaby, Port Moody and Coquitlam with an 11km advanced light rapid transit line between Lougheed Town Centre in Burnaby and Douglas College in Coquitlam. The project includes a 2000 metres single bore long tunnel and seven stations. SNC-Lavalin was chosen as the primary contractor to construct the Evergreen Line. The tunnel construction employed a 9.86 metre diameter EPB TBM made by Caterpillar.

The TBM was named “Alice” in honor of Alice Wilson, Canada’s first female geologist. The tunnel project started in March 2014 and is scheduled to complete in 2015.

The TBM encountered complex geology comprised of tills, glacial outwash, glaciomarine and ice contact deposits, as well as boulders with maximum UCS of 350 MPa. 3.1.5 The Seymour Capilano Twin Tunnels Project,

Vancouver, BC The Twin Tunnels component of the project comprises twin, 3.7 m diameter, 7.2 km TBM bored tunnels, the 180 m deep Seymour Shaft as the main launch shaft, and two 4 m diameter, 268 m deep raise bore exit shafts at Capilano.

The Twin Tunnels have been planned as predominantly unlined tunnels sited at depth entirely within granitic bedrock.

Figure 7. Robbins TBM launching for Saymour Capilano Tunnels (from Robbins Company)

The project was originally awarded to Bilfinger Berger

that completed about 50% of the tunnel construction before leaving the project.

When the project came to a halt in January 2008, the two 3.8m-diameter TBMs were struggling to navigate the worst ground conditions of the five support classes identified in the GBR. Class V support includes “steel ribs and shotcrete” in “extremely poor” rock (Tunnel Talk, 2009)

The project restarted in 2009 with a different contractor (Frontier-Kemper/J.F Shea/Aecon JV) on the same design utilizing the Robbins Beam TBMs. The tunnels were complete in 2013. 3.1.6 Other notable tunnels in Western Canada Other notable tunnel projects in Western Canada are included but not limited to the content of Table 3. Table 3 Western Canada Tunnels

Tunnel Means Year Use Location

Fraser Canyon Tunnels

D&B 1957 Road Fraser, BC

Cassiar Tunnel

C&C 1992 Road Burnaby, BC

Connaught Tunnel

D&B 1885 Rail Revelstoke, BC

George Massey Tunnel

Immersed Tubes

1959 Road Richmond, BC

Big Hill Spiral Tunnels

D&B 1909 Rail Canadian Rockies, BC

Port Mann Water

TBM 2014 Utility Surrey, BC

3.2 Central Canada (Ontario) 3.2.1 Saint Clair River Tunnels First Tunnel The tunnel works started from the need to solve one major challenge for the Grand Trunk Railway. Everything and everybody had to be unloaded in Sarnia, put on a ferry for the short ride across the St. Clair River and then back onto railroad cars for the continued trip to Detroit or Chicago. The solution was a tunnel. In 1884 the railroad chartered a St. Clair Tunnel Company, with funding from both American and Canadian governments. Construction began in January, 1888 with crews working from both sides using a new shield method. The tunnel was completed and opened for service on September 19, 1891.

The tunnel was an engineering marvel. Underneath many broad rivers, the soil is soft and porous making digging challenging. The new shield method used for this tunnel involved excavation in a compressed air environment. A cast iron lining was put in place as the digging progressed. The crews met at the appropriated location on August 30, 1890. This was the world’s first railroad tunnel under a river.

Figure 8. Compressed Air Shield Cross-section (from Oil-Electric.com)

The portions under the shore were driven without compressed air. But when the banks were reached, brick bulkheads containing air locks were built sealing the tunnel, and the section beneath the river, about 3,710 feet long, driven under air pressure of 10 to 28 pounds bar (above atmosphere.)

For most of the way, the clay was firm and there was little air leakage. It was found that horses could not survive in the compressed air, and so mules were used under the river.

Through the initial assessment was marked by lack of confidence. For that reason a special consideration was given to risk of failure and the work was planned to start from vertical shafts so in case the tunnel will fail there would be no money spent on the alignment approach to shaft locations.

In April 1888, the shafts were started near both riverbanks, but before reaching the design depth the almost fluid clay and silt flowed up faster than it could be excavated and the initial plan was abandoned and long open cut approach cuts were made and the work finally began.

Figure 9. TBM assembly (from Oil-Electric.com)

After the portals were established, several hundred metres back from each bank the tunneling work itself began. The portions under the shore were driven without compressed air. When the banks were reached, brick

bulkheads containing air locks were built across the opening and the section beneath the river, about 1,130 m long, was constructed under air pressure of 10 to 28 pounds above atmosphere.

For most of the alignment, the ground consisted of firm clay. The tunnel was not perfectly sealed and there was some little air leakage. It was found the hard way that horses could not survive in the compressed air, and therefore mules were used under the river.

In the firm clay, excavation was carried on several feet in front of the shield. A crew of about twelve miners worked at the face. However, in certain strata the clay encountered was so fluid that the shield could be simply driven forward by the rams, causing the muck to flow in at the door openings without excavation.

After each advance, the rams were retracted and a ring of iron lining segments was erected. Here, for the first time, an "erector arm" was used for placing the segments, which weighed about half a ton.

“In all respects, the work advanced with wonderful facility and lack of operational difficulty. Considering the large area, no subaqueous tunnel had ever been driven with such speed. The average monthly progress for the American and Canadian headings totaled 455 feet, and at top efficiency 10 rings or a length of 15.3 feet could be set in a 24-hour day in each heading. The 6,000 feet of tunnel was driven in just a year; the two shields met vis-à-vis in August of 1890" (Vogel 2012).

Second Tunnel By the early 1990s, CN Rail had commissioned engineering studies for a replacement tunnel to be built adjacent to the existing St. Clair River tunnel.

Unlike when the first tunnel was hand dug from both ends, a Tunnel Boring Machine named “Excalibore” was employed to bore the entire tunnel. The TBM was designed and manufactured by the Lovat Tunnel Equipment Inc. The TBM was one of the first Earth Pressure Balance Machine utilized in Canada and had a diameter of 9.53 metres.

Figure 10. “Excalibore” TBM (from Lovat Inc.)

The tunnel started on the Canadian side and dug its

way to the U.S. The TBM started mining on ---and broke through at

Port Huron on December 8, 1994. After that the first tunnel (original) was retired and filled in with sand. 3.2.2 Niagara Falls Hydro This preoject holds the world record by a Beam TBM (15.2 m DIA). The TBM was named Becky in the honour of Sir Adam Beck.

The TBM bored a tunnel about 10.4 km long, 140 m beneath the City of Niagara Falls from the Sir Adam Beck Generating Complex to a water intake complex above Niagara Falls.

The geology varied, consisting of limestone, dolostone, sandstone, shale and mudstone. The rock strength ranges from 15 to 180 MPa (2,100 to 26,000 psi), with most of the rock in the 40 to 100 MPa (5,800 to 15,000 psi) range.

Figure 11. TBM “Bertha” assembly on site, (from HMM)

Contractor Strabag AG of Austria took a unique approach to the tunnel construction for the Niagara power project when they elected to use a Main Beam hard rock TBM to excavate the 14.4 m diameter tunnel. Strabag had previous experience with Robbins HP-TBM™ technology from the Second Manapouri Tailrace Project in New Zealand. For Niagara, Strabag again elected to go with a Robbins HP-TBM™, this one being the world’s largest hard rock TBM. This machine is the first ever to be fitted with back-loading 20″ cutters (The Robbins Company, 2006).

The 10,400 metres of tunnel was realized with a beam TBM supplied by The Robbins Company of US. The tunnel was designed by Hatch Mott MacDonald and constructed by Strabag. The construction consisted of a two passes with rock dowels, steel ribs, mesh and shotcrete, followed by a polyolefin membrane and unreinforced 600 mm thick cast-in-place concrete lining.

Project notable events were related the TBM onsite first time assembly and large over break at several locations.

3.2.3 Sheppard Subway

The project included 5.5 km of subway tunnel and 5 stations. McNally-PCL-Foundation JV constructed 6.4 km of twin tunnel with five stations to connect Yonge Subway with Don Mills Road. Two Lovat 5.9 m-diameter EPBs exceeded scheduled advance rates of 15 m/day/face in glacial deposits with boulders. The 3.3 km west drives were completed towards the end of 1998. The TBMs were removed for minor refurbishment prior to starting the east drives and completed tunnelling by the end of1999. The tunnels, 5.2 m in internal diameter were finished with precast concrete lining with 6+1 segment ring configuration. 3.2.4 Spadina Expansion

Four Caterpillar EPB TBMs were procured by TTC for Toronto's 8.6km (5.4 mile) Toronto-York Spadina Subway Extension. The project was divided in two contracts one awarded to the JV of Aecon-McNally-Kiewit and the second one to the JV of OHL & FCC.

The tunnels were complete by late fall of 2013.

Figure 2. TBMs named “Yorkie” and “Torkie” breakthrough (from HMM)

One of the notable events was under passing Schulich Building. To mitigate potential settlements extensive compensation grouting was performed from three shafts constructed the east and north sides of the building. 3.2.5 Other notable tunnels in Central Canada Other notable tunnel projects in Central Canada are included but not limited to the content of Table 4. Table 4. Central Canada Tunnels

Tunnel Means Year Use Location

Brockville Tunnel D&B 1860 Rail Brockville, ON

Detroit-Windsor Tunnel

IT1 1930 Road Windsor, ON

Heart Lake Road TBM 1973 Road Mississauga,

Tunnel ON

York-Durham Trunk Sewer

TBM 1980 Utility Markham, ON

John Street Pumping Discharge

TBM 1981 Utility Toronto, ON

Markham Road Sanitary Sewer

TBM 1982 Utility Markham, ON

YDSS TBM 2008 Utility Richmond Hill, ON

SEC TBM 2014 Utility Durham, ON

Eglinton LRT TBM 2014 Rail Toronto, ON 1 IMMERSED TUBE

3.3 Eastern Canada 3.3.1 Underground Interceptor along St. Lawrence River,

Montreal, QC

The tunnel 2.9 metre diameter tunnel was excavated between two access shafts using a full face Robbins TBM, model 91-155. The rock cover for the tunnel underlying the St. Lawrence River varied between 6 and 10 metres.

The 6,835 metres long tunnel was part of a project including 3 access shafts, one diffusing shaft and a waste water plant (Schneeberger, Cote and Aziz 1989).

The TBM was equipped with a protective roof about 3m long. Following excavation ground support consisting of rock bolts was installed. Tunnelling underneath the Aqueduct required extensive roof reinforcement. The reinforcement was designed in the form of a roof vault, supported by steel ribs, and installed at a distance of 4m behind the TBM advance.

Figure 33. Tunnel support solution under Aqueduct, (from Schneeberger, Cote and Aziz 1989) 3.3.2 Point Aconi Cooling Water Intake, Nova Scotia The 4.5m DIA tunnel measured 1 kilometre long and was constructed with a Jarva Mark TBM by Boretec Ltd. The TBM was retrofitted to suit the gassy environment. Tunnel work started on Nov. 1991 and completed on Feb.1992.

The tunnel support consisted of 100mmx100mm circular steel sets with 1.2m spacing and complemented with wooden lagging installed in the roof and the floor. The support was erected at 1.5m behind the tunnel face under a 2m long “fingers” roof support.

The TBM stroke being 600m, a steel set was installed after every second push. Horizontal probe drilling (75mm DIA) was employed to check for gases and water presence 45m ahead of the tunnel face.

The Tunnel had a final lining consisting of CIP Concrete of 3.72m. Following the cast in place concreting backfilling grout was used to fill any voids. 3.3.3 Other notable tunnels in Eastern Canada Other notable tunnel projects in Eastern Canada are included but not limited to the content of Table 5. Table 5. Eastern Canada Tunnels

Tunnel Means Year Use Location

Mount Royal Tunnel

D&B 1913 Rail Montreal, QC

Louis Hippolyte Lafontaine Bridge-tunnel

IT1 1967 Road Montreal, QC

Hydro Quebec TBM 1990 Cable Montreal, QC

St.Jerome Tunnel

TBM 1998 Montreal, QC

Petro Canada Pipeline

TBM 2002 Pipeline Montreal, QC

La Romaine Hydroelectric Complex

D&B 2012 Hydro Havre Saint Pierre, QC

1 IMMERSED TUBE

4. CANADIAN TUNNELLING TRENDS 4.1 TBM Manufacturing and Commissioning The Robbins Company introduced the concept of TBM first time assembly on site.

This approach eliminates the full assembly and testing at the manufacturer’s facility before dismantling and shipping the TBM to site. The on-site first time assembly was made possible by the recent design techniques including implementation of 3D CAD tools, modular TBM design and more advanced and stringent Quality Assurance.

Depending on the size and complexity of the tunneling machine being produced, and whether the machine is new or refurbished, the savings in both schedule and cost can be substantial.

On a small, 3.0 meter simple machine the savings in schedule can be as little as a month or so and perhaps 5,000 man- hours and 100,000 US dollars in transport cost. On a complex 10 meter or larger machine the savings in schedule can be as much as several months and possibly 15,000 man-hours can be saved as well (Roby and Willis, 2010).

Beside manufacturer cost savings, the Projects could benefit by a shorter lead time for TBM procurement.

The on site first time assembly was implemented first in Canada at the Niagara Tunnel Project in 2006.

4.2 TBM Refurbishment More often the Owners are requesting that TBM refurbishment is carried by or under direct assistance of the original TBM manufacturer to reduce risk of TBM failures. A full warranty for the refurbished TBM, similar to new TBMs is requested from the manufacturer.

TBM refurbishments at or near tunnelling site is often used to reduce cost associated with logistics and/or mitigate schedule.

These trends and approaches are not only visible in Canada and the USA; but globally.

4.3 Tunnelling Industry Innovations 4.3.1 Vertical Tunnelling Applications to mining industry and Shaft Construction:

• Vertical Shaft Machine for excavation and shaft construction in soft ground

• Shaft Boring Machine in Rock

• Shaft Drilling Jumbo

4.3.2 Multi-Mode TBMs Provides flexible machine technology for highly variable ground

• Combination of EPB and Open-face TBM

• Combination of Open-face and Slurry TBM

• Combination of EPB and Slurry TBM

4.3.3 Energy-Efficient TBMs With constant increase in energy costs, efforts for developing cost effective- energy efficient TBM systems are visible in the tunnelling industry also. Monitoring Power consumption provides useful data to designers to quantify effective values of the voltage and current strengths.

Reducing the Power Consumption of the electrical consumers is achieved by optimizing the TBM design:

• Selection of energy-saving components (i.e., LED lighting)

• Computerized models to analyze TBM energy needs

• Optimized TBM utilization, startups and shutdown of unutilized systems without compromising safety.

ACKNOWLEDGEMENTS Data compilation for this paper was made possible by Caterpillar, City of Edmonton, Fed Hapgood, Herrenknecht AG, HMM, Lovat Inc., Robert McDonald, McNally Inc., The Robbins Company, Strabag and TAC.

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