Year: 2021

Turkish TBM Records, Twice Over

History has been made twice over at Turkey’s Eşme-Salihli Railway Tunnel where a 13.77 m (45.18 ft) diameter Robbins Crossover XRE TBM has set new world records for best day, week, and month in the 13 to 14 m (42.6 to 46 ft) diameter range. The machine broke all three records first in May with 25.3 m (83 ft) in one day, 117 m (383.8 ft) in one week, and 345.6 m (1,134 ft) in one month, then again in June with 28.5 m (93.5 ft), 133.2 m (437 ft), and 455.4 m (1,494 ft) respectively. The TBM, which sat in storage for seven years before being newly upgraded for this project, proves the robust durability of Robbins machines.

Crossover Machine Launch Site

Thus far the Robbins machine has encountered a mix of mudstone and gneiss.

The Crossover TBM surpassed all previous performance rates by a machine in its size range. The closest another 13 to 14 m (42.6 to 46 ft) machine has come to these numbers was a 13.7 m (45 ft) diameter mixed ground TBM that achieved a 7 m (23 ft) average per day and a best day of 12 m (39 ft) at the Eurasia Tunnel project.

Onur Kansu, TBM Manager for project contractor Kolin Construction, attributes the machine’s success to the team operating it: “The most important reason for achieving fast advance rates is that we have an experienced and qualified team. If we open it up even further, such a team allows us to anticipate the malfunctions and to go to the solution in a very short time. In addition, all necessary maintenance is carried out on time, and the appropriate consumables are selected to increase the performance.”

The machine launched on its 3.05 km (1.90 mi) bore at the end of March 2021 as part of the Ankara-İzmir High Speed Railway Project for the Turkish State Railways (TCDD). Thus far the machine has encountered a mix of mainly mudstone with gneiss. “When we look at the overall tunnel geology,’ said Kansu, “we are excavating in complex and weak ground. In this geology, the advantages of the Robbins XRE TBM are highly favorable. The Robbins XRE TBM shows high performance in both complex and weak ground. It should also be noted that the TBM is very strong when looking at parameters such as torque and thrust.” To get through the challenging conditions, the large diameter XRE has a number of unique features. The large diameter design enables both a screw conveyor and belt conveyor to remain in place, enabling swift conversion between modes, and operation in full EPB and hard rock modes.

Regarding the future of the Turkish tunneling industry, Kansu is optimistic about the effects these new records will have: “It has been seen how well the engineers and application teams in Turkey have excelled in complex geologies and the large-scale tunneling industry. At the same time, it has shown to the whole world, especially Turkey, that with the right choices, it is possible to carry out excavations of this scale and complex geology without any problems and quickly. This project will be a pioneer in the Turkish tunneling industry, showing that faster and more economical tunnels can be built.”


Robbins XRE TBMs Cross the Finish Line in Massive Metro Project

In Spring 2021, the second of two 6.65 m (21.8 ft) diameter Robbins Crossover XRE TBMs made its third and final breakthrough for India’s Mumbai Metro Line 3. The first machine made its final breakthrough for the project in late April. The tunnel drives were a triumph for joint venture contractor Larsen & Toubro and the Shanghai Tunnel Engineering Company (L&T – STEC), as the crew and equipment overcame unpredictable terrain, high-pressure water ingress, and government-imposed lockdown orders during the Covid-19 pandemic.

Surya I breakthrough

The first of the Robbins Crossover machines broke through in April 2021.

The two custom-built machines were selected to bore parallel 2.9 km (1.8 mi) tunnels between the Cuffe Parade station and CST stations, breaking through into several station sites along the way. “It is the first time in India that Dual Mode, Crossover type TBMs equipped with a horizontal screw conveyor and high torque / high speed (two-speed) cutterhead drives were used. Overall, the performance of the Crossover TBMs was found satisfactory and we are in the process of shifting these TBMs for the L&T Chennai Metro project,” said Mr. Palwinder Singh, Head – Tunnel Construction for the L&T – STEC JV.

In another first for India, the Crossover TBMs employed a unique technique in a 554 m (1,820 ft) long section from Hutatma Chowk to CST stations. They were used in the benching of the NATM Platform tunnel through basalt rock (removal of the bottom section of rock remaining in the station after conventionally removing the top section). “This requires fine control on the operational parameters of the TBM because only 25% of the cutterhead is excavating the rock mass, while the remaining 75% of the cutterhead has no contact with rock or soil. In addition, the TBM was relaunched without using a reaction frame, instead taking reaction from half segments erected during the benching of the NATM Platform Tunnel. These innovative concepts were accomplished for the first time in India at Mumbai Metro Line-3, Package 1, and I therefore have many reasons to feel proud on the completion of tunneling,” said Singh.

L&T – STEC made impressive progress throughout tunneling despite the many exacting circumstances surrounding the scope of work. Above ground, the joint venture not only had to navigate the restrictions of working within an urban environment, such as limited work hours and the slow removal of muck due to minimal space and traffic, but also faced concern for major structures such as the Mittal Towers and the historic Bhikha Behram Well located along the tunneling route. The Crossover TBMs excavated with only 15 to 20 m (49 to 65 ft) of cover separating them from these important structures, which had to be instrumented to monitor vibrations, movements, and potential settlement.

Benching the NATM station

In a first for India, the Robbins Crossover TBMs were used in the benching of the NATM Platform tunnel through basalt rock in a 554 m (1,820 ft) long section from Hutatma Chowk to CST stations.

Underground, L&T – STEC faced a complex geological mix of fresh greyish basalt, soft volcanic tuffs, shale, and breccias—consolidated rocks of angular fragments of disintegrated volcanic rock. One of the biggest concerns, however, came from the tunnels’ proximity to the coastline of the Arabian Sea. During one point, TBM 1 was only 25 m (82 ft) from the coastline, with the invert level of the tunnel running approximately 22 m (72 ft) below mean sea level. As anticipated with circumstances such as these, the Crossovers faced a significant amount of groundwater with up to 300 liters/min during their excavation.

Despite these obstacles, the TBMs were still able to maintain impressive rates. TBM 2 even completed one push in a swift 14 minutes. “In fact, the boring rate of the Crossover TBMs was never an issue for us. It was only limited by the rate of muck removal and we could have finished the tunnels much faster,” said Singh.

The Robbins Crossover TBMs were the first machines of their kind employed in India, using both a horizontal screw conveyor and high torque / high speed (two-speed) cutterhead drives.

L&T engineers were highly involved in the specifications and designs of the machines and worked closely with Robbins to prepare for the challenges the project presented. While L&T had extensive tunneling experience, tunneling with a Crossover machine was entirely new to them. To remedy this, Robbins provided a team of key personnel to train L&T in all aspects of the machines’ design and operation. “Working with Robbins field service was more than satisfactory. Even during the Covid-19 pandemic times, Robbins field service was available 24 hours a day, 7 days a week. What else can one expect?” said Singh.

Each milestone reached on this project is another step closer toward significantly improving the lives of Mumbai residents. As the financial capital of India and one of the most populated cities in the world, Mumbai is faced with an excessive amount of road traffic. It currently takes up to two hours to drive the 25 km (15 mi) distance from Cuffe Parade to the airport—the same trip on the finished metro will take a mere 50 minutes. The completion of Mumbai Metro Line 3, which is expected in 2025, will not only save residents transit time, but is expected to initially decrease road traffic in the area by 35%, reducing daily fuel consumption by 460,000 liters.


Rock Tunnels at High Water Pressure: Non-Continuous Pressurized TBMs vs. Slurry

The choice of TBM type is never easy, but it becomes especially challenging when faced with a hard rock tunnel with expected high water flows and pressure.  Slurry Shield tunneling has a long history of being used in these conditions to minimize the risk, though this method has brought with it other risks along with cost considerations. At recent projects around the world, another method has been proven to effectively manage these project risks without utilizing Slurry Shield tunneling: Shielded, Non-Continuous Pressurized (NCP)-TBM tunneling in rock with a comprehensive grouting program. In this paper, the authors will analyze the use of Shielded NCP TBMs at projects around the world as compared with slurry shield tunneling in rock under water pressure. Recommendations will be given in order to establish a clear picture of the optimal tunneling method.


Cutting Edge 2021

Event Name: Cutting Edge Conference
Dates: November 15-17, 2021
Location: Dallas, Texas, USA

Come visit Robbins at the Cutting Edge Conference, and learn more about the largest hard rock TBM ever to operate in the USA at the Mill Creek Project. The 11.6 m (38.1 ft) diameter Robbins Main Beam TBM is excavating an 8 km (5 mi) long tunnel in Dallas, and is the conference’s main field trip.  The annual Cutting Edge Conference examines the latest advances in tunneling technology, its methodology and how they can be harnessed to assist the nation’s major upcoming underground projects. Visit Robbins at our booth and talk to our experts with decades of experience on our latest projects and products.


The Utility Expo

Event Name: The Utility Expo 2021
Dates: September 28-30
Location: Louisville, Kentucky, USA
Venue: Kentucky Exposition Center
Booth: N1961

Covering more than 30 acres, The Utility Expo is the largest event for utility professionals and construction contractors seeking the latest industry technologies, innovations, and trends. Visit Robbins at our indoor booth N1961 and talk with our expert staff on our latest products and projects. We look forward to seeing you there!


Robbins XRE TBM bores Eşme-Salihli Railway Tunnel

A Robbins Crossover machine is boring Turkey’s 3.05 km (1.90 mi) Eşme-Salihli Railway Tunnel through mixed conditions including sandstone, gravelstone, claystone, and siltstone for contractor Kolin Construction.

A Robbins 13.77 m (45.18 ft) diameter Crossover XRE TBM launched recently in spring 2021 in Eşme, Turkey. The large machine is boring the 3.05 km (1.90 mi) Eşme-Salihli Railway Tunnel through mixed conditions including sandstone, gravelstone, claystone, and siltstone. Contractor Kolin Construction expects some occasional groundwater and weak rock between 5 to 9 MPa (720 to 1,300 psi) UCS, with the potential for a gassy environment.

The titanic TBM was launched after more than seven years in storage, and following a few upgrades to systems to ensure they meet the newest safety and efficiency standards. “I am very happy that the TBM has been launched. Up to now, the machine has bored nearly 500 m (1,600 ft) in gneiss and mudstone. This is an opportunity for Robbins to prove that large diameter TBMs can bore in such tunnels, even in very complex geology and difficult ground conditions,” said Yunus Alpagut of ATES, Robbins’ Turkish subsidiary. Alpagut went on to explain why the project is so important: “Recently, there have been large diameter, non-Robbins machines that have failed at projects such as the high-speed railway in Bilecik, so this is very important to show the Turkish tunneling industry that large machines are up to the challenge.”

To get through the challenging conditions, the large diameter XRE has a number of unique features. The large diameter design enables both a screw conveyor and belt conveyor to remain in place, enabling swift conversion between modes, and operation in 100% EPB and hard rock modes.

In EPB mode, the screw conveyor operates as in any typical EPB machine. The screw features a replaceable inner liner and replaceable carbide wear bits for abrasion protection. A mixed ground cutterhead is fitted with knife bits that can be switched out with disc cutters in harder conditions. The machine design includes a man lock for cutterhead inspection and changes, and mixing bars inside the mixing chamber.

Esme Salihli XRE Cutterhead Rotates

The large diameter Robbins Crossover TBM has bored nearly 500 m (1,600 ft) in gneiss and mudstone as of May 2021.

To convert to hard rock mode, the mixing bars and initial portion of the screw conveyor can be optionally retracted. EPB knife bits are then replaced with disc cutters on the cutterhead, and the EPB scrapers on the cutterhead are replaced with bucket lips. Muck paddles are installed in the cutterhead to allow the muck to fall into the muck chute. A hydraulic muck ring allows a chute attached to the bulkhead to move forward and down at a diagonal angle, allowing rock chips to be deposited in the chute and through the screw conveyor onto the TBM belt conveyor. To keep up production rates in both modes, the Robbins Torque-Shift System is used: a two-speed gearbox that enables efficient tunneling in hard, mixed, or soft ground.

The Eşme-Salihli Railway Tunnel is part of the Ankara-İzmir High Speed Railway Project for the Turkish State Railways (TCDD). The 508 km (316 mi) line will eventually connect Polatlı in Ankara Province to Izmir, the third most populous city in Turkey, surpassing the Istanbul-Ankara High-Speed Railway as the longest rail line in the country once complete. The double-track railway system will convey passengers at top speeds of 250 km/h (160 mph), completing the journey between the two cities in 3.5 hours—a journey that would normally take 6.5 hours by car.


BTS 2021

Event Name: BTS Conference and Exhibition
Dates: September 30-October 1
Location: London, UK
Venue: QEII Conference Centre
Stand: B26

Register for the British Tunnelling Society’s upcoming conference and learn about the industry’s latest trends with 800+ other tunneling professionals. Debate and analyze the latest trends and topics in underground construction, and be sure to check out the lecture by Robbins President Lok Home. Stop by our stand B26 to talk about the latest Robbins products and projects with our team of international experts.

Robbins Lecture Description
Thursday September 30
Session 3 – Innovation in Action
2:00 – 2:20 PM

Non-Circular Tunnelling: A New Way Forward – Lok Home, Robbins President

When a flat roadbed is needed, is a circular TBM the best way to go? In this exclusive presentation, Robbins President Lok Home will discuss methods and equipment currently being used in the mining industry for flat inverts, and its increasing potential for use in civil tunneling. Home will look at case studies in both mining and civil tunneling industries to demonstrate that by using non-circular TBMs, a flat invert can be safely and economically created in one pass.


The Green Alternative: Small Hydro Machines for Clean Energy

When you’re faced with a hard rock tunnel on your next small hydro project, which tunneling method works best? Intake tunnels can be at diameters as small as 2 meters and at steep grades of up to 45 degrees.  Compared with the conventionally used method of Drill & Blast, small diameter tunneling machines offer increased production rates and reduction in cross section, among other benefits. The uniquely designed machines are engineered to take on steep gradients, and can bore tunnels kilometers long with minimal impacts to the surrounding environment.

In this complimentary, 60-minute webinar we discuss the use of small diameter tunneling machines on projects throughout Norway, where their popularity is increasing, as well as the method’s suitability on projects worldwide. Listen in on our conversation with Robbins Norway General Manager and Civil Engineer Sindre Log as we discuss recommendations for small hydro tunnels in hard rock.  Join us for a live Q&A session at the end to get a thorough answer from our expert speaker.

Watch the Recording


Most Momentous: 2021 Global Project Updates

From China’s largest Crossover TBM launch to an epic 13.77 m diameter XRE that began boring recently in Esme, Turkey, we’ve compiled the year’s most momentous events thus far. Read on to find out about Robbins machines embarking on tunnels large and larger.

Twin Crossover TBMs for Chongqing

Two 6.91 m (22.6 ft) diameter XRE machines are currently boring sections of the Chongqing Metro Phase 2 in ground conditions ranging from weathered mixed granite to weathered pegmatite and adamellite. The twin machines are the first of their kind in China, and are part of a trend towards more geologically challenging tunnels in China. To date, the machines have achieved up to 365 m (1,197 ft) advance in one month, with rates expected to ramp up as the machines progress.

Chongqing Metro Team

The team takes a moment to mark the assembly of one of two Robbins Crossover machines in Chongqing, China.

An Epic XRE Launch in Esme

In Esme, Turkey, a massive 13.77 m (45.2 ft) diameter Crossover XRE TBM began its bore for contractor Kolin Construction. Launched in late March 2021, the unique TBM is designed to tackle mixed ground conditions including sandstone, gravelstone, claystone and siltstone along the 3.05 km (1.9 mi) Esme-Salihli Railway Tunnel. The XRE can swiftly convert between hard rock mode using a belt conveyor and EPB mode using a screw conveyor, as both remain in place inside the machine.

Esme XRE TBM Launch

Launch of the 13.77 m diameter Robbins XRE TBM for Turkey’s Esme-Salihli Rail Tunnel.

Tunneling below Lake Ontario

A Robbins 7.95 m (26.1 ft) diameter Single Shield TBM launched recently on March 26th from an 85 m (280 ft) deep, 14 m (46 ft) diameter shaft. The machine, for the Ashbridges Bay Outfall with contractor Southland Holdings LLC in Toronto, ON, Canada has the task of boring a 3.5 km (2.2 mi) long tunnel below Lake Ontario. The completed tunnel will connect up to 50 in-lake risers to enable efficient dispersion of treated effluent over a wide area of the lake.

Asbridges TBM Launch

The Robbins Single Shield TBM for the Ashbridges Bay Outfall Tunnel launched on March 26, 2021. Photo: Alfredo Garrido

China’s Largest Crossover TBM

The largest ever Crossover (XRE) TBM in China launched in late March 2021 in Guangzhou for contractors Sichuan Jinshi Heavy Equipment Leasing Co., Ltd and CREC Bureau 2. Onsite First Time Assembly (OFTA) was utilized to build the 9.16 m (30 ft) diameter Robbins TBM, taking just four months from contract signing to machine launch. The hybrid machine is boring the 2.5 km (1.6 mi) long Pazhou Line Lot PZH-1 of the Pearl River Delta Intercity Railway Project, which will offer better commutes for Guangzhou residents traveling to and from University City.

Pearl River Delta TBM Assembly

The Robbins Crossover XRE TBM at the Pearl River Delta site was assembled using Onsite First Time Assembly in just four months from contract signing.


To Grout or Not to Grout?

When you’re faced with a hard rock tunnel where there are expected significant sections under high water pressure, which tunneling method do you choose?

While Slurry Shield tunneling has a long history of addressing this problem, this method has not always been problem free. Another highly effective method exists that can lower costs and risks: Non-continuous Pressurized (NCP) TBM Tunneling with a shielded machine.  When used in rock with a comprehensive grouting program or sequential advance in EPB mode, NCP TBMs have proven that they can successfully navigate high water pressures safely and effectively.

In this complimentary, 45 minute webinar we debate the pros and cons of Slurry and NCP TBMs, and look at case studies of both types of machines in hard rock under high water pressures.  Listen in on our conversation with Robbins President Lok Home and Brad Grothen P.E., Robbins Technical Director, as we discuss recommendations and the future of tunneling in rock under water pressure.

Watch the Video