Mumbai, Dec 16 (IANS): The Mumbai Metro Rail Corporation Ltd on Wednesday announced that nearly 90 per cent of the tunnelling work on the 33.5 km long fully underground Colaba-SEEPZ Mumbai Metro Line 3 has been completed.

Of the 54.50 km dual tunnel for up and down lines, the MMRCL has till date completed 49.50 km tunnelling, for the city's first fully underground Metro Line 3, a portion of which will go underneath the Mithi River.

The latest breakthrough was achieved at Dadar Metro Station with the completion of the 1.12 km long tunnel from the Siddhivinayak Temple to Dadar, marking the completion of the 10.96 km tunnel under the Package 4.

"The tunnelling work, using 3 Tunnel Boring Machines, in 4 out of the total 7 packages is now 100 per cent complete. The tunnelling in Package 4 was particularly challenging as all stations are located in close proximity to developments, active road traffic and important religious sites," said MMRCL Managing Director Ranjit Singh Deol.

He said that Dadar, considered the heart of the city, will provide connectivity that will ease commuting woes of the Mumbaikars, on the Line 3.

MMRCL's Director (Projects), S.K. Gupta said that the Herrenknecht-made TBMs, equipped with earth pressure balance technology, started its main tunnelling drive on July 7 and completed the stretch using 805 rings, and now the overall progress of Dadar Metro Station is around 42 per cent.

The Package 4 included Siddhivinayak Temple, Dadar, and Shitladevi stations with 8 important breakthroughs at various locations on the Colaba-SEEPZ alignment, which will cater to some of the most important business and residential locations including the Mumbai International Airport.

It also includes a 170-metre long dual-tunnel passing under the Mithi River on the Dharavi-Bandra Kurla Complex sector, making it India's second under-river tunnel after the one underneath Hooghly River in the Kolkata Metro.