By the end of the year, four tunnel-boring machines (TBM) from two directions would have created subterranean pathways for travel to the Chennai Central Metro Rail station, the largest underground station in the city.
For a start, the first TBM that started tunnelling from Washermanpet five years Buckingham Canal on Sunday night and is likely to break through the Chennai Central Metro station wall this week.
The other TBM from Washermanpet will complete tunnelling work by the end of December.
Also, two more TBMs from the Egmore Metro Rail station, tunnelling towards Central station, will reach their destination by mid-November and December respectively.
According to officials of Chennai Metro Rail Limited (CMRL), it was particularly difficult to tunnel from the Madras High Court Metro Rail station to Chennai Central as the TBM had to drill through rock. “It was challenging and time-consuming. The tunnel stretches to a maximum depth of 28 metres below the ground, even deeper than the Buckingham Canal near the Central station. Tunnelling has taken time in this section from Washermanpet to Chennai Central because the soil conditions have been unpredictable; in some areas there is loose soil and in other areas, hard rock,” an official said.
Meanwhile, the construction of stations between Washermanpet and Chennai Central, covering a distance of about 6 km, is under way. Soon after the tunnelling is complete, the work on creating cross-passages and laying tracks will begin. The cross-passages are those that are present in between every 250 metres of the tunnels for passengers to escape in case of an emergency.
These works may take at least 6-8 months, sources said. Though officials plan to finish the work by the end of next year, sources said it may take longer. Chennai Central, the largest of the underground stations which will serve as one of the major junctions for Chennai Metro Rail, may also become functional only by the end of next year.
