Tunnelling contractor Tata Projects Ltd will use the S96 machine to build Corridor 3, from Venugopal Nagar Station to Kellys Station. The work involves the construction of 18km of bored tunnels. Terratec will provide five of the seven TBMs required for the package.

The mixed ground EPBMs were chosen because of the variable geological conditions along the alignment; boreholes indicate sand, silt and clay on the tunnel drives, as well as some weathered rock.

The TBM’s mixed-face dome-style cutterheads are designed to work effectively in the geology on these contracts at pressures of up to 4 bar. Other features include VFD electric cutterhead drives, tungsten carbide soft ground cutting tools that are interchangeable with 17in roller disc cutters, high torque screw conveyors, active articulation systems and state-of-the-art guidance and control systems.

As the TBMs progress, they will install 1,400mm-wide by 275mm-thick universal reinforced concrete lining rings consisting of five segments plus a key.

Chennai Metro is India’s fourth longest metro system, in one of the country’s fastest growing cities. The network currently consists of two lines covering a distance of 54.65km. The new Line 5 will have 48 stations and connect from Madhavaram to Sholinganallur. The project is expected to be completed in about four years.

In the past nine years Terratec has supplied 40 TBMs for Indian projects, including Phase III of the Delhi Metro, Lucknow Metro, the Ahmadabad Metro, Pune Metro and Mumbai Metro.