Breakthrough celebrations in Mumbai 07 Mar 2019

The first of seven Terratec TBMs working on the 33.5km underground Line 3 for the Mumbai Metro broke through after its first drive. Breakthrough was celebrated on the first 690m section of the UGC-06 contract from the CSIA International Airport Station to Sahar Road Station. It is one of three 6.68m Terratec dual mode hard rock TBMs working for the J Kumar/China Railway No. 3 Engineering Group (CRTG) JV on the 4.45km-long twin-tube UGC-06 package and on the 4.94km long twin tube UGC-05 contract. “The Terratec dual-mode TBM worked successfully through mixed geology and considerable water ingress,” said Haluk Emre, Package 6 Project Manager for the JV.

Breakthrough for the first Terratec TBM

The Terratec single shield TBMs are equipped to operate in either open or closed mode in the predominantly fresh and slightly to moderately weathered basalt and breccia expected on the two contracts. The hard rock cutterheads are equipped with heavy-duty 17in cutters, that are interchangeable with ripper tools, and feature large bucket openings to provide a 10% opening ratio. The 2,000kW electric variable frequency drives provide a maximum cutterhead rotation of 7 rev/min and a torque of up to 8,500kNm to excavate efficiently in harder rock zones and cope with more fractured zones along the alignment. The machines also have active shield articulation and a two component annular backfill grout system.

In addition to the three new hard rock TBMs, the J Kumar/CRTG JV is also operating two re-manufactured 6.61m diameter mixed rock Terratec EPBMs through a section of highly weathered ground on contract UGC-05.

Fig 1. Contract packages on the 33.5km long Mumbai Metro Line 3

“The five J Kumar/CRTG TBMs are performing well and have excavated a total of more than 5.7km of tunnel to date,” said Bill Brundan, Terratec Site Operations Manager.

A further two new 6.68m diameter dual-mode hard rock TBMs are being used by the Hindustan Construction/Moscow Metrostroy JV to build the twin running tunnels for the 4km long Line 3 UGC-02 contract. Both machines were deployed from the Chhatrapati Shivaji Terminal (CST) launch shaft and are currently travelling towards the Mumbai Central Station TBM receiving shaft, having now completed 3.7km of tunnel with progress rates of up to 525m/month.

When complete, the 33.5km long Mumbai Metro Line 3 will be the first underground metro line in the city and will connect Cuffe Parade business district in the far south to the Santacruz Electronics Export Processing Zone (SEEPZ) in the north with 26 underground, and one at-grade, stations (Fig 1).

Construction of the line is divided into seven tunnel-and-station packages that were awarded to five contracting joint ventures in 2016. These five contractors will deploy a total of 17 TBMs with Terratec being the lead TBM supplier on the project with a 41% market share. Terratec field service support experts are on call to assist TBM operations with close monitoring throughout. In total, the seven Terratec machines have excavated 9.5km or 42% of their planned drives.