A 1,516 metre-long tunnel was excavated between Mandi House and Janpath metro station in Delhi by the Delhi Metro Rail Corporation (DMRC) within 182 working days.

The tunnel work is part of the Phase-III metro rail project in the capital city and the tunnel has an internal diameter of 5.8 metre.

The tunnel passes beneath a lot of important central Delhi buildings like American Centre, Nepal Embassy, Fulbright House, Antriksh Bhawan, Scindia House, Electrical Sub Station, Janpath Market and Jeevan Prakash Building.

On September 25, 2012, the tunnel boring machine (TBM) was lowered in the Mandi House shaft and after assembly of the TBM below the ground the initial drive began on October 23.

The TBM broke through from the North West Shaft of the Janpath Metro station close to the Tibetan Market. The maximum depth is 24 metre below the earth's surface and the excavated earth was deposited at Mukundpur Depot.

By next month, another TBM, which is working on the 1492 metre long Down Line, is expected to breakthrough.