Pair of Crossover TBMs Completes Triple Tunnel Drives in Mumbai
Jul 28, 2021
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.
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.
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.
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.
The News in Brief:
- The second of two 6.65 m (21.8 ft) Robbins Crossover XRE TBMs made it’s final breakthrough at India’s Mumbai Metro Line 3 in spring 2021.
- The two Robbins XRE TBMs were uniquely designed for basalt, tuff, shale and breccias, and featured a screw conveyor as well as two-speed cutterhead drives.
- JV contractor L&T-STEC achieved good advance rates in tough ground conditions, completing a push in as little as 14 minutes.
- The Robbins Crossover TBMs are the first in India to be used in the benching of a NATM tunnel as they passed through an intermediate station site.
- The completion of Mumbai Metro Line 3, which is expected in 2025, will decrease road traffic by 35% and correspondingly reduce daily fuel consumption by 460,000 liters.
More News and Articles
Jul 24, 2024
News
UK utilities place multiple orders for settlement tank technology
Northumbrian Water, Southern Water, and Dŵr Cymru upgrading wastewater sites
Three UK water utilities have agreed orders for the installation of a total of six conical settlement …
Jul 22, 2024
Article
Reusing wastewater, rethinking water: Maharashtra's roadmap
How Maharashtra turns wastewater into a resource
Water resource management is a critical issue globally, and in India, the state of Maharashtra is pioneering efforts to regulate and …
Jul 19, 2024
News
Kansas City advances fire hydrant leak detection technology
An acoustic fixed-base pipe monitoring technology that uses fire hydrants to host multi-sensor devices, has already found more than 30 leaks for Kansas City Water, says Lou Rossetti …
Jul 17, 2024
News
When two bores right a wrong
The Edge Underground team is adamant: there is always a risk of things going wrong on a trenchless project, even for the most prepared contractor.
Experience and having the right equipment can be the difference between …
Jul 15, 2024
News
Adapting to a region’s growing water and wastewater needs
Gippsland Water has completed two major projects to provide local communities with water security. Trenchless Australasia takes a look at the two projects helping increase water supply …
Jul 12, 2024
News
Connections made in Glastonbury
Difficult ground conditions called for a specialist solution when new PE pipes for potable water services had to be installed underneath two, 10-metre road crossings in the grounds of the UK’s ultimate music festival …
Jul 10, 2024
Article
The Water-Energy Nexus: Interdependence and Challenges
Niclas Andersson, CEO of AirWater2All, explains the connection between water and energy. The importance of this connection and the areas in which it needs to be considered are explained …
Jul 08, 2024
News
Minimising cultural impacts with trenchless technology
Yarra Valley Water is leveraging the benefits of trenchless technology to lessen impacts on the Upper Darebin Creek branch sewer project.
The project consists of building a 2.7km sewer pipe …
Jul 05, 2024
News
SprayWall: Reinforcing Underground Infrastructure with Unmatched Strength
In the trenchless technology industry, finding a rehabilitation solution that offers ease of installation and exceptional structural integrity is paramount.
For three decades, …
Jul 01, 2024
News
“Don’t let stereotypes hold you back”
Trenchless Australasia sat down with Rob Carr project manager Marie Piette to discuss her career and work at the microtunnelling contracting company.
From Norway to Cambodia and now Perth, Western Australia, …
Jun 28, 2024
News
Transforming Wastewater: Towards Climate-Neutral Sewage Treatment
Baden-Württemberg’s Minister President Winfried Kretschmann recently toured the Büsnau Training and Research Sewage Treatment Plant, where a pioneering project led by researchers …
Jun 26, 2024
News
Bothar advances with significant new contracts
Having commenced work on the Fitzroy to Gladstone Pipeline earlier this year, Bothar Boring and Tunnelling has announced the award of further contracts as part of its ongoing collaboration with …
Contact
The Robbins Company - A Global TBM Company
Desiree Willis
Technical Writer
29100 Hall Street
OH 44139 Solon
United States
Phone:
+1 253 872 4490