Multiple Delhi breakthroughs for Terratec

- On 8 September TBM S37 on contract CC-34 completed excavation on the down line from the Vikas Puri Station to the cut and cover shaft near to the Janakapuri West Station. The contractor is joint venture between Hindustan Construction Company Ltd. of India and Samsung E&C of Korea.

- On 30 September TBM S28 on contract CC-24 breakthrough after completing the drive between the Nizzamudin and Ashram Stations. The contractor was a joint venture between J.Kumar Infraprojects of India and China Railway Third Group (CRTG) of China.

- On 7 October TBM S36 on contract CC-34 completed excavation on the up line to the cut and cover shaft near to the Janakapuri West Station, like its twin S37 one month earlier.

- On 19 October TBM S26 on contract CC-24 completed excavation on the down line from the Lajpat Nagar Station to the Vinoba Puri Station.

A Terratec spokesman discussed the machines' technical specifications. "Terratec's S36 and S37 TBMs are 6.52m-diameter EPB Shields with a classic soil configuration equipped with a Spoke-Type cutterhead of 58 per cent opening ratio, which has been proven to be very efficient to excavate this type of soil along the drive. The cutterhead mounted soft ground tools, but it is designed to allow the replacement for 17in roller disc cutters, making the TBM to be able to bore through the diaphragm walls and cope with the presence of any unexpected obstacle on its way, such as old wells or foundations.

"The S26 and S28 TBMs are 6.61m-diameter mixed/rock EPBMs. The TBMs mount 960kW VFD electric driven cutterhead with a versatile design, which mounts 17in roller disc cutters interchangeable for soft ground cutting tools."

The spokesman added that the mixed/rock EPB design had already been successful boring quartz rock with uniaxial compressive strength over 200MPa on earlier Delhi work.