STN: The construction work on Delhi Metro Phase 4 moved ahead with a significant tunnel breakthrough. On 25 June 2025, Tunnel Boring Machine (TBM) S64B, known as Shalini, made a successful breakthrough at Vasant Kunj Metro Station. This work is part of the Golden Line under civil contract package DC-08.
The Golden Line, also called the Aerocity–Tughlakabad corridor, is a 23.622 km stretch. The breakthrough took place at one of the four stations under this corridor.
Progress of TBM S64B in Delhi Metro Phase 4
J Kumar Infraprojects operates TBM S64B. It is the first machine deployed for the 6.116 km stretch covered under package DC-08. The TBM created a 1,550-metre tunnel from Kishangarh to Vasant Kunj.
TBM S64B is 91 metres long. Its cutterhead diameter is 6.61 metres. It dug the tunnel at an average depth of 22.86 metres. The depth ranged from 15.48 metres to 30.25 metres across the stretch.
The tunnel is made up of 1,105 precast concrete rings. Each ring has an internal diameter of 5.8 metres. These rings form the tunnel’s structure.
Earlier Tunnel Achievements and Future Plans
Before this, the parallel tunnel was completed using TBM Sonakshi. That breakthrough occurred on 6 March 2025.
J Kumar Infraprojects is responsible for this package. Delhi Metro Rail Corporation (DMRC) awarded the DC-08 contract to the company for ₹1,611.74 crore.
The contract includes building a 6.116 km section between chainage (-)760 metres to 5,356.285 metres. This part of the Golden Line includes four stations:
- Aerocity
- Mahipalpur
- Vasant Kunj
- Kishangarh
Delhi Metro Phase 4 Expansion Overview
Delhi Metro Phase 4 will expand the city’s metro network by 112.32 km. Out of this, 40.109 km will run underground. The remaining distance will be elevated or at ground level.
The Aerocity–Tughlakabad corridor covers 23.622 km in total. Of this, 19.343 km will be underground. The rest will be above ground.
This corridor will improve metro access in South Delhi. It will also help passengers travelling to the airport via Aerocity.
Key Details from the Tunnel Breakthrough
- Tunnel Length Completed by TBM S64B: 1,550 metres
- Number of Rings Used: 1,105 precast rings
- Diameter of Each Ring: 5.8 metres (internal)
- TBM Depth: 15.48 to 30.25 metres
- TBM Length: 91 metres
- TBM Cutterhead Diameter: 6.61 metres
Significance of the Achievement
The recent breakthrough is an important milestone for Delhi Metro Phase 4. It shows steady progress on one of the busiest corridors under construction.
The use of modern TBMs allows quicker and safer tunnel excavation in dense urban areas. This helps reduce traffic disruptions above ground and speeds up project timelines.
