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Author: Robbins
Twin Robbins EPBs make milestones near Taj Mahal
On June 21, 2024, crew members celebrated a milestone at India’s Agra Metro Project. A 6.52 m diameter Robbins EPB had completed an intermediate breakthrough into SN Medical College Metro Station. The breakthrough was a significant achievement for the contractor, Afcons Infrastructure – Sam India Consortium, as the machine continues its bore on the 29.40 km Agra Metro Phase 1 project.
The Robbins spoke-type EPB TBM completed a 508 m long bore through soft clay strata in less than three months.
“We want to congratulate Afcons-Sam India on the continued success at Agra Metro. They’ve completed this most recent bore in less than three months in a dense urban setting, which is a great result,” said Robbins President Lok Home. “We are confident in the long life and exceptionally robust design of our TBMs, especially when they are well maintained and properly operated.”
The machine was launched on March 23, and completed the 508 m bore through soft clay strata. The breakthrough is the fourth for the Robbins EPB, nicknamed ‘Yamuna’. Previous breakthroughs included one in close proximity to the Taj Mahal. About 200 m or two soccer fields away from the world-renowned structure, that breakthrough was heavily monitored and tracked by the office of the Prime Minister and many others.
‘Yamuna’ is the first of two 6.52 m Robbins EPBs to reach the SN Medical College Metro Station. It’s twin, nicknamed ‘Ganga’, is currently boring a parallel tunnel. The two spoke-type Robbins EPBs, refurbished and customized for soft ground conditions, were originally launched in February and April of 2023. The condition of the TBMs has been good as they broke through into various intermediate stations, requiring no further refurbishments and brief maintenance periods of 15 to 20 days before they were launched again. The TBMs have required minimal usage of spares and cutters during their bores, and both TBMs have thus far successfully bored within their contractual time frames. The bores thus far have included: Ramleela Maidan to Agra Fort Station (334 m); Agra Fort Station to Shahjahan Gardens Midshaft (175 m); Shahjahan Gardens Midshaft to Taj Mahal Station (1175 m) and finally Agra College to SN Medical College (508 m).
Now, the Robbins TBM ‘Yamuna’ will be moved through the station box of SN Medical College and recommissioned in the direction of Jama Masjid Station, also known as Mankameshwar Mandir Station. It will cover a distance of about 1290 m.
With the completion of the 11th breakthrough, seven more remain: two at Raja ki Mandi, two at Agra College, one at SN Medical College, and two at Jama Masjid (Mankameshwar).
Afcons – Sam India Consortium was awarded the Rs. 1819.79 crore civil construction contract for underground Package AGCC-02 by Uttar Pradesh Metro Rail Corporation (UPMRC) in March 2022, with a 48-month timeline. Twin tunnels link the seven stations at Taj Mahal, Agra Fort, Jama Masjid, SN Medical College, Agra College, Raja Ki Mandi, and RBS College.
The high-profile project is one of many metro railway tunnels underway in the country from Mumbai to Delhi, Bangalore to Chennai. Rajat Jain, Sr. Manager of Sales & Operations at Robbins India, sees it as a trend likely to continue: “India has emerged as a top market for tunneling due to several key factors and trends. These include India’s rapid urbanization and demand for infrastructure development, advances in tunneling technology that have made the process more efficient and safer, and India’s growing economy. Tunnels play a crucial role in developing seamless connectivity across the country, reducing travel time, and enhancing the efficiency of goods movement.”
Long Haul TBM: Use of a Rebuilt Main Beam Machine at the DigIndy Tunnel System in Indianapolis, IN
TBMs can last for decades and be rebuilt project after project with proper maintenance. How successful can rebuilt TBMs be? At the DigIndy Tunnel System in Indianapolis, Indiana, USA, a rebuilt TBM was used to great effect. The 6.2 m diameter Main Beam, originally manufactured in 1980, bored 40+ km of tunnels and set three world records in its size class of 6 to 7 m, including a best month of 1,754 m. In this paper, the authors analyze the TBM rebuild, performance and lessons learned to make recommendations for future projects seeking to use rebuilt TBMs over long distances.
Evaluating TBM Design and Performance, 30 Years Apart: The Lesotho Highlands Water Tunnel, Phase 1 and Phase 2
Two massive tunnel projects 30 years apart: The Lesotho Highlands Water Project (LHWP) is a multi-phased project that has taken place over decades to provide water to the Gauteng region of South Africa and to generate hydroelectricity for Lesotho. Phase I tunneling began in 1992 and utilized multiple Main Beam TBMs to bore long tunnels in basalt and dolerite ground conditions. Phase II, now under construction, consists of 38 km of transfer tunnel to be excavated by both TBM and drill & blast.
This paper details the design for the TBMs to be used on the Phase II tunnel, while comparing the modern-day machines to the history-making Main Beams used in the 1990s. It draws some conclusions and lessons learned about boring in volcanic rock at depth utilizing Main Beam vs. Double Shield TBMs.
Overcoming Mountainous Geology at Nepal's Sunkoshi Marin Project
Learn more about the Sunkoshi Marin Diversion Multipurpose Project (SMDMP) in this in-depth video featuring a record-setting Robbins Double Shield TBM. Find out how the crew were able to bore through mountainous geology at an impressive 1,503.3 m in one month and 72.6 m in one day.
Swift Robbins TBM breaks through 11 Months Early
On May 8 in Nepal’s Sindhuli District a crowd of people attending the breakthrough of a speedy TBM had much to celebrate. The 6.4 m diameter Robbins Double Shield machine had overcome incredibly challenging geology to cross the finish line 11 months ahead of schedule. Nepal’s Sunkoshi Marin Diversion Multipurpose Project (SMDMP), at 13.3 km in length, is one of the longest TBM-driven tunnels through the Himalayan mountain range and is only the second such tunnel to be completed in the country. View the breakthrough video here.
At a breakthrough ceremony attended by Nepal’s Prime Minister Pushpa Kamal Dahal, the crowd celebrated an epic TBM breakthrough 11 months ahead of schedule.
“The overall design of the Robbins TBM is proven, and the equipment’s performance and integrity are excellent. Additionally, its adaptability to the Himalayan geological conditions is very impressive,” said Mr. Liu Fengfan, SMDMP Project Manager for contractor B-2/COVEC (China Overseas Engineering Group Co. Ltd and China Railway No. 2 Engineering Group Co Ltd).
Ground conditions included two major fault zones with challenging and varied geology ranging from highly jointed mudstone, sandstone and conglomerate to quartzite, granite, and more. The tunnel was bored through mostly igneous rock with maximum overburden of 1,320 m.
The TBM and its experienced crew were able to persevere through multiple instances of the shield becoming trapped with bypass tunnels required to free it, including one instance 4 km into tunneling that required 27 days’ worth of work to free the machine from collapsing and squeezing ground. Despite the challenges, the crew were able to more than make up the time with swift advance rates including an impressive 1,503.3 m in one month and 72.6 m in one day, both project records set in March 2024.
The success of the machine, despite adversity, is in part due to its proven design. The refurbished TBM was originally used at a smaller diameter on Nepal’s first TBM-driven tunnel, the Bheri Babai Diversion Multipurpose Project (BBDMP). The design incorporates many of the same components of that original machine, and the process involved final assembly on location at the jobsite. It’s something the contractor sees as a positive: “One of the highlights is that this machine integrates the overall structure of the 5.06 m diameter TBM from the Bheri Babai project. After upgrading to 6.4 m diameter, all new front shield components were not assembled in the factory. Instead, we adopted Onsite First Time Assembly (OFTA). This was very effective, and I find it particularly noteworthy,” said Mr. Jin Haikuan, Deputy Project Manager & TBM Production Manager for B-2/COVEC.
With tunneling complete, the work of providing both power and water can begin. The tunnel is connected to a new 28.6 MW surface powerhouse on the Marin River to alleviate the shortage of power supply in the area. It will also be used for farmland irrigation in the districts of Dhanusha, Mahottari, Sarlahi, Rauthat and Bara in the Terai Plain, diverting water from the Sunkoshi River to the Marin River for the project owner, the Department of Water Resources and Irrigation under Nepal’s Ministry of Energy, Water Resources & Irrigation.
The project’s successful completion is a triumph not only for the communities benefiting, but also for the future of tunneling in Nepal. “B-2/COVEC and Robbins have successfully introduced and spread TBM technology in Nepal and shown the advantages of it. This country needs more tunnels,” said Robbins President Lok Home at the breakthrough ceremony. “To have these good performances on these first two projects is really a good thing for the country and our industry.”
NAT 2024
Event Name: North American Tunneling Conference (NAT)
Dates: June 23-26, 2024
Location: Nashville, Tennessee, USA
Venue: Gaylord Opryland Resort & Convention Center
Booth: 901
Come join us in Nashville, TN June 23-26 at the North American Tunneling Conference, the premier tunneling event focusing on current projects, challenges, and successes in tunneling. Stop by our booth 901 to learn more about our ongoing and successful tunneling projects, and be sure to check out our insightful technical presentation.
Technical Presentation
Monday June 24
TBM Technology Session
Presidential Chamber A
11:25 – 11:45 AM
Long Haul TBM: Use of a Rebuilt Main Beam Machine at the DigIndy Tunnel System in Indianapolis, IN
Presented by Doug Harding, Vice President, Robbins & Christian Heinz, Tunneling Division Project Manager, J.F. Shea Construction
World Tunnel Congress 2025
Event Name: ITA-AITES World Tunnel Congress
Dates: May 9-15, 2025
Location: Stockholm, Sweden
Venue: Stockholmsmässan
Stand: B04:10
Come join us May 9-15 in Stockholm, Sweden for the ITA-AITES World Tunnel Congress, the premiere event for tunneling and underground construction. More than 2,000 professionals are set to take part in the world’s top-attended tunneling conference, where hundreds of technical papers will be presented on the latest topics of interest. Stop by our stand B04:10 to converse with our expert international team, and find out the latest about our products and projects.
Use of a Tunnel Boring Machine on Nepal’s First and Second TBM-Driven Tunnels
Nepal’s mountainous terrain has historically been a challenge to tunnel through. That very terrain also holds great promise for hydropower – a resource that the country is now beginning to tap into. Launched in October 2022, a 6.4 m Double Shield TBM is making Nepal’s hydropower plans into a reality as it bores the 13.1 km headrace tunnel for the Sunkoshi Marin Diversion Multipurpose Project (SMDMP). The tunnel is connected to a 28.6 MW surface powerhouse on the Marin River.
The SMDMP is the machine’s second tunnel: on its 12.2km first tunnel (the Bheri Babai Diversion Multipurpose Project/BBDMP), the TBM finished nearly one year early and achieved 1,202 m advance in one month. It was the first instance of TBM use in the country.
In this paper, we examine the successes and lessons learned in Nepal’s mountainous conditions during excavation of both the SMDMP and BBDMP.
Robbins Double Shield Sets Record in Nepal
In the southern Himalayan mountains of Nepal, a Robbins Double Shield TBM has crossed into new territory. At the end of June 2023, the machine turned in an impressive advance rate of 1,224.13 m in one month – a record for Himalayan geology and believed to be a TBM record within the Indian Subcontinent. Launched in October 2022, the 6.4 m diameter machine has been boring the 13.3 km headrace tunnel for the Sunkoshi Marin Diversion Multipurpose Project (SMDMP).
At the end of June 2023, a 6.4 m diameter Robbins Double Shield TBM achieved an impressive advance rate of 1,224.13 m in one month.
Multiple factors played into the successful result. “Proper TBM selection for the existing subsurface is the key reason for success. The Double Shield is the most logical TBM type and has played a major role in this successful journey. Operation, maintenance, and an experienced, dedicated team are additional factors,” said Mitra Baral, Project Director of SMDMP under the Department of Water Resources and Irrigation, part of Nepal’s Ministry of Energy, Water Resources & Irrigation.
Contractor Covec/B-2 echoed those sentiments: “The designed adaptation of the TBM & backup provided by Robbins is verified to be scientific and good under the geology, which are Siwalik stratum and the lower Himalayan zone–both quite complex and variable. The performance of the equipment is generally stable,” said Covec/B-2’s Project Manager, Mr. Liu Feng Fan.
Contractor B-2/COVEC (China Overseas Engineering Group Co. Ltd and China Railway No. 2 Engineering Group Co Ltd) have navigated the Robbins TBM through two major fault zones with challenging and varied conditions ranging from highly jointed mudstone, sandstone and conglomerate to quartzite, granite, and more.
The record result is all the more impressive considering the adversity the machine has overcome to date. Approximately 2,156 m into the excavation the machine became stuck in jointed sedimentary rock, requiring nine days of intensive work and a bypass tunnel to free it. As the machine progressed to more than 4 km in, the geology changed to dolomite, slate, schist, quartzite and phyllite. The machine became stuck a second time 4,669 m in due to collapsing and squeezing ground, requiring a further 27 days of work to release it.
Despite the challenges early on, the machine and its experienced crew have persevered. Currently the TBM is more than 8.3 km into the tunnel and boring in high strength granite, having passed through the two major fault zones predicted on the tunnel alignment. “Timely support from Robbins has made for a good relationship and teamwork. It has been quite important for the success of our project,” said Mr. Liu.
Prajwal Man Shrestha, General Manager of Robbins Nepal, emphasized that the successful results thus far are a milestone for the use of TBM tunneling in the country: “There are now private sector hydropower developers considering the use of a TBM for their project instead of the conventional D&B method. Very soon we may see that most tunnels longer than 6 or 7 km will be exploring the possibility of using TBMs on their project.”
As for the future of tunneling in Nepal, Mr. Baral is positive it will continue to grow and evolve: “Many TBM projects could be planned for many different areas. Taking into consideration that Nepal is a mountainous country with complex geology, tunnels are indispensable not only for irrigation and hydropower but also roads, railways, water supply, and even metro lines in the cities.”
Final Breakthrough at Bahçe-Nurdaği Railway
In June 2023, a resilient 8.0 m diameter Robbins Single Shield TBM completed its second tunnel at Turkey’s Bahçe-Nurdaği Railway. The machine completed 9.6 km of tunneling, adding on to the 9.2 km it completed in its initial railway tunnel in 2020 – for a total of more than 18 km bored.
The Robbins TBM completed 9.6 km of tunneling, adding on to the 9.2 km it completed in its initial railway tunnel in 2020 (pictured) – for a total of more than 18 km bored.
“We are very proud to complete this tunnel in difficult rock formations with our excellent team by utilizing an extremely powerful and strong Robbins Single Shield TBM,” said Deniz Şahin, TBM Chief for contractor İntekar Yapı Turizm Elektrik İnşaat San. ve Tic. Ltd. Şti.
Geology in the second tunnel was comparable to the first, including incredibly hard and abrasive metasandstone with quartz, with an average of 220 MPa (31,900 psi) UCS and a Cerchar abrasion value of 3.87. The rock has some of the most extreme hardness and abrasiveness ever measured in Turkey.
After its first bore in the difficult ground, the machine required some inspection and repairs. “Robbins Field Service was always available when we requested,” said Şahin. “The biggest repairs we undertook with Robbins Field Service technicians were the main bearing seal change and checking and repairing of the TBM before launching it on the twin tunnel after the completion of the first tunnel. Both operations were completed in a short time due to good planning with Robbins technicians.”
The machine began its second bore in February 2021, achieving a best monthly advance rate of 411 m. “During tunneling we performed a normal maintenance program as given in the TBM manual, and the machine had minimum downtime, which shows the durability of Robbins TBM in very hard and abrasive rock,” said Şahin.
The Robbins Single Shield TBM was designed to bore in incredibly hard and abrasive geology including metasandstone with quartz – some of the hardest rock ever encountered by a TBM in Turkey.
“The Robbins TBM has performed extremely well in this project with minimal downtime and good advance rates to complete the longest twin tube railway tunnels in Turkey,” said Yunus Alpagut, Robbins representative in Turkey.
The twin rail tunnels, for owner Turkish State Railways Directorate (TCDD), will provide an economic boost to a region recovering from two consecutively devastating earthquakes with magnitudes of 7.8 and 7.6 that occurred in February 2023. The project site is located very close to the intersection of two large active fault zones, the East Anatolian Fault (EAF) and Dead Sea Fault (DSF). The tunnels were inspected after the event and were found to have sustained only minor cracking in a few segments. The new rail line will provide service between the towns of Bahçe and Nurdağı, and is part of the TCDD’s plan to overhaul the railway connection in southeastern Turkey by providing a shorter, faster route in one of the country’s busiest railway corridors.