STN: J Kumar Infraprojects Limited (JKIL) recently completed a major tunneling milestone for Mumbai Metro Line-7A. Tunnel Boring Machine (TBM) Dhruv made its final breakthrough at the Airport Colony Shaft. This tunnel is part of a 3.17 km underground stretch that connects Gundavali to Chhatrapati Shivaji Maharaj International Airport (CSMIA).
TBM Dhruv’s Role in Mumbai Metro Line-7A
TBM Dhruv, also known as T60, is a dual-mode Terratec machine with a diameter of 6.68 meters. It was earlier used by the J Kumar – CRTG joint venture during the construction of Mumbai Metro Line-3. In that project, it completed tunneling for two sections between Dharavi Station and Marol Naka.
Before being deployed on Line-7A, TBM Dhruv was refurbished at J Kumar’s facility located on Ghodbunder Road. The machine began its current work in November 2023. It started from the shaft at Terminal 2 Station of CSMIA and headed towards the Airport Colony Ramp.
During this 1.65 km up-line tunnel drive, the TBM passed above Metro Line-3’s twin tunnels and below the Sahar Elevated Access Road. It also crossed under several important utility lines in the area.
Scope of Work Under Package CA-48
In September 2019, the Mumbai Metropolitan Region Development Authority (MMRDA) awarded J Kumar Infraprojects the contract for Package CA-48. The total value of this contract was ₹1,998 crore.
The scope of work includes:
- Building a viaduct and ramp
- Constructing twin underground tunnels
- Developing two metro stations: Airport Colony and CSIA Terminal 2
These stations will connect with the operational Line-3 (Aqua Line). In the future, they will also link to Line-8, which is planned to reach the Navi Mumbai International Airport.
Final Stages of Tunneling Work
Another tunnel boring machine, TBM Disha (T62), completed the down-line tunnel in April 2025. With TBM Dhruv completing the up-line tunnel now, the main tunnel work for Mumbai Metro Line-7A is complete. Only the cross-passages between the two tunnels are pending.
Expected Timeline for Completion
Based on the remaining work such as system installation and station development, it is expected that Mumbai Metro Line-7A will not become operational before the third quarter of 2027. This timeline matches the usual pace for metro construction in Mumbai, which includes rigorous testing and approvals.