Year: 2023

Tunneling in Turkey: The Esme Salihli Railway

Large diameter tunneling in mixed ground has historically been seen as a challenge, but a recently completed tunnel in Turkey has changed the conversation. A 13.77 m diameter Crossover XRE TBM bored the Esme Salihli Railway Tunnel at world-record-setting rates of up to 721.8 m in one month, making it the fastest TBM over 13 m in diameter. What allowed the project to achieve such high advance rates?

A Robbins Crossover machine that bored 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.

Machine Design for Variable Geology

The Eşme-Salihli Railway Tunnel is a short section of high-speed railway, measuring 3.05 km (1.90 mi) through mixed conditions. Contractor Kolin Construction conducted 15 core drillings at 200 m intervals prior to the start of construction, with results predicting occasional groundwater and weak rock between 5 to 9 MPa (720 to 1,300 psi) UCS, with the potential for a gassy environment. Rock and soil types included sections of gneiss, sandstone, claystone, mudstone, quartzite, and silt.

A dual mode rock/EPB TBM design was created for the project, in which no design elements were sacrificed in the engineering: The machine was fully capable of operating in 100% EPB mode or 100% Hard Rock Single Shield Mode. The TBM was designed for sections of hard rock and mixed ground, in highly variable conditions. For details on the design, check out this technical paper.

The cutterhead in hard rock mode.

The cutterhead in EPB mode.









Epic Results

The 13.77 m Crossover XRE machine launched on its 3.05 km (1.90 mi) bore at the end of March 2021. While some of the crossover features proved beneficial the TBM was able to utilize the screw conveyor for mucking for the complete tunnel drive, which was a further benefit for the project’s overall schedule.

What allowed the machine to perform at high rates of advance? Utilization charts reveal that 38% of the total time was spent on excavation, 27% on ring assembly, 21% on planned downtime such as maintenance, and 14% on unplanned downtime.

Productivity pie chart.

When looking at planned downtime, the most time was spent on cutterhead maintenance at 28%, followed by crew breaks at 22%. An average machine push took 60 minutes, while ring builds averaged 42 minutes.

Delays caused by mechanical, hydraulic or electrical failures were very low. The contractor cited the main reasons for minimal downtime, and thus high advance rates, as regular planned maintenance, cleaning, an experienced team, and an adequate supply of spare parts. Ultimately the tunnel was completed in just 6.5 months.

Monthly advance rate chart in meters bored and rings built.

In Conclusion

Large diameter, dual mode rock/EPB machines can and will excavate mixed ground conditions efficiently – even at world record rates. While similar projects in Turkish geology have met with challenges, the Esme-Salihli tunnel shows that with proper maintenance and a knowledgeable crew, equipment downtime can be kept to a minimum and advance rates can remain high.

Personnel from contractor Kolin Construction and Robbins celebrate the breakthrough of a Crossover (XRE) TBM after it completed Turkey’s Esme Salihli Railway Tunnel.

Incredible India: Machines on the Move in Agra and Delhi

India’s metro network has undergone extensive growth in recent years, and is showing no signs of slowing. Multiple Robbins machines are part of tunneling work in cities across India, including Agra and Delhi.

Agra Metro: From First Site Acceptance…

On February 16, 2023 the Robbins crew and contractor SAM India celebrated the site acceptance test for the first of two 6.65 m diameter EPB TBMs at Agra Metro. The machine began boring a 1.3 km long tunnel in soft soils, for Uttar Pradesh Metro Rail Corporation Ltd.

The Robbins team celebrates a successful site acceptance test for the first of two Robbins EPBs at Agra Metro.

Robbins EPB TBMs

The Robbins EPBs, seen during their Factory Acceptance, are designed for soft soils.

To Second Site Acceptance…

With the first TBM well into tunneling, a second 6.65 m Robbins EPB underwent site acceptance on April 13, 2023 to bore a parallel 1.3 km long tunnel in soft soils. The crew gathered for a ceremony before sending the TBM on its way.

The crew gathers for the site acceptance ceremony of the second Agra metro EPB.

The crew gathers for the site acceptance ceremony of the second Agra metro EPB.

To First Breakthrough!

Just a few days later on April 26, 2023 the first machine made an intermediate breakthrough into a station site, completing the Jama Masjid to Agra Fort stretch of the metro. The machine bored a total of 345 m in sand and clay, and broke through to a celebration by the crew and project teams.

The crew anticipate the first breakthrough of the Robbins EPB at Agra Metro.

The crew anticipate the first breakthrough of the Robbins EPB at Agra Metro.

The Robbins EPB breaks through to much fanfare at Agra Metro.

The Robbins EPB breaks through to much fanfare at Agra Metro.

New Delhi Metro: Machines Ramping Up

On February 27, 2023 the first of two 6.65 m diameter EPBs for the Delhi Metro (owner is Delhi Metro Rail Corporation) was completed in the Robbins Gurgaon, India facility. The mixed ground machine will bore a 3 km long tunnel through rock with some gravel, sand, silt and clay for contractor Afcons Infrastructure Ltd.

The first of two TBMs set to bore in mixed ground at Delhi Metro, during the factory acceptance in February 2023.

The first of two TBMs set to bore in mixed ground at Delhi Metro, during the factory acceptance in February 2023.

A second machine factory acceptance followed in April 2023. Both machines are scheduled to launch on parallel tunnels this summer.

The second Delhi Metro EPB, designed to bore in mixed ground conditions.

RETC 2023

Event Name: RETC 2023
Dates: June 11-14
Location: Boston, MA, USA
Venue: Sheraton Boston Hotel
Booth No: 506

The Rapid Excavation and Tunneling Conference (RETC) is sponsored by the Society for Mining, Metallurgy & Exploration (SME). The show focuses on developments, technology, trends, and innovations that directly affect the tunneling and underground construction industry through a wide variety of technical presentations. Stop by the Robbins booth #506 to meet with our expert staff and found out the latest about our products and projects. Be sure to check out our technical presentations as well:

9:30-10:00 AM
Enhanced Probe Drilling and Pre–Grouting Design and Recommendations on Hard Rock TBMs
Presented by Stryker Magnuson, Robbins Design Engineer

10:30-11:00 AM
Record-Setting Tunnel Boring Below Lake Ontario at the Ashbridges Bay Outfall Tunnel
Presented by Doug Harding, Robbins Vice President


WTC 2023

Event Name: ITA-AITES World Tunnel Congress 
Dates: May 12-18, 2023
Location: Athens, Greece
Venue: Megaron Athens International Conference Centre (MAICC)
Stand: 59

Come join us May 12-18 in Athens, Greece 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 59 to converse with our expert international team, and find out the latest about our products, projects, and talks at the conference.

Technical Presentations:

Tuesday May 16
Track 2, Theme 4 Mechanized Tunneling
4:30 – 4:50 PM
Mitropoulos Hall
Record-Setting Large Diameter Mixed Ground Tunneling in Turkey: The Eşme-Salihli Railway Tunnel
Presented by Detlef Jordan, Sales Manager Europe

Wednesday May 17
Track 4, Theme 6 Tunneling in Challenging Conditions: Case Histories and Lessons Learned
12:40 – 1:00 PM
MC2 Hall

Lessons Learned During Excavation of the Incredibly Challenging Yin Han Ji Wei Water Diversion Tunnel
Presented by Lok Home, Robbins President


Event Name: NASTT No-Dig 2023
Dates: April 30-May 4, 2023
Location: Portland, Oregon
Booth: 322

Join experienced Robbins staff at the largest trenchless technology conference in the world, NASTT No-Dig in Portland, Oregon. Find out more about our line of Robbins Small Boring Units (SBUs) —game changers in the trenchless industry, saving you time and money on your next hard rock or mixed ground utility tunnel.

Notice of Retraction and Apology

To all Visitors of our Site:  I declare that our website contained information that was inaccurate, and in retrospect, was offensive and disrespectful to our longtime Customer and highly qualified construction Client, Obayashi Corporation of Japan, along with their Joint Venture (JV) Partners, Taisei Corporation and Kosei Corporation.  The referenced Project Site name is Hiroshima Expressway 5 Shield Tunnel Project and the Robbins Technical Article titled, which states as if the JV selected the wrong type of TBM for the Hiroshima Project.

We retract the statements made in our article such as, “Contractors who are used to tunneling in soft ground may not realize that when using a Slurry TBM in rock, inspections must be frequent due to increased cutter consumption.  We have seen this borne out on recent projects such as the Hiroshima Expressway Line 5 in Japan” because these statements were not based on facts and were incorrect. This statement reads as if the contractor did not review other optional TBM types, when in fact, the JV did indeed study all TBM types and methods to excavate this Express Tunnel.

There were additional incorrect statements made in the Article as follows:

  • The same paragraph of the Article continues,”…, and they (contractor) were expecting up to 13 bar water pressure. This high pressure water zone was only in a small section of the overall tunnel length, about 5 percent.
  • The Article further states, “The contractor in Hiroshima had grouted off from the surface a planned safe zone in which to inspect the cutterhead without requiring a hyperbaric intervention, but this strategy did not go according to plan. The abrasive rock damaged the cutters and cutterhead before they could reach the safe zone, resulting in unplanned delays“.
  • The same paragraph of the Article continues, “…grout off from the surface a planned safe zone…“.

The reason for choosing a Slurry type TBM was not solely based on the high water pressure but was also a result of the JV’s extensive review of all aspects of the tunnel requirements.

There was no plan to grout a “safe zone/safe haven” from the surface as other plans for cutter changes were in place and such plans have proven to be effective over numerous cutter change events.

Robbins commits to have more peer review and where a Client is involved, to have the Client review prior to presenting such data on our website.