The 26m-deep inclined adit will facilitate construction of 3.3km of tunnel through NATM, by allowing simultaneous access for tunnelling 1.6m on each side. TBMs, with 13.6m diameters, will build 16km of the 21km tunnel, and the remaining 5km will be constructed using NATM. The adit will allow vehicular access to the main tunnel during construction.
The excavation work for the adit started in December last year. A total of 214 controlled blasts were carried out using 27,515kg of explosives.
Shafts are now being built at BKC, Vikhroli and Sawli for the bored section of the tunnel. A 7km stretch will extend under the sea at Thane Creek.
The 16km section will require 76,940 segments to form 7,441 rings. Each ring will comprise nine curved segments and one key segment, with each segment 2m wide and 0.5m thick.
The casting and stacking yard, covering an area of 9.9ha, is currently being commissioned in Mahape. The yard will feature nine sets of moulds, each containing 10 pieces. Four sets of these moulds have already been installed on-site.
