Archive · 23 Jun 2025
SLBC Tunnel Project Halts TBM Use, Focuses on Drill and Blast
The Srisailam Left Bank Canal tunnel project is changing how it's being built.
After a tunnel section collapsed, killing workers and damaging a machine, the government decided to stop using the tunnel boring machine (TBM) at the outlet.
They fear a similar collapse.
Instead, they'll use a drill-and-blast method to finish the tunnel.
The second TBM is stuck and will be removed in pieces.
This change will likely delay the project, which aims to bring water to Nalgonda district.
Second tunnel boring machine (TBM) at the Srisailam Left Bank Canal will not be used due to safety concerns.
The decision follows a February 22 collapse that killed eight workers and damaged another TBM.
Authorities will switch to the traditional drill-and-blast method for the remaining tunnel work.
The unused TBM is stuck 20.43 km inside the outlet section and awaiting repairs.
Work on dismantling the second TBM has already begun.
- Who
- Authorities working on the SLBC tunnel project.
- What
- Decision to stop using a TBM for the Srisailam Left Bank Canal tunnel project and switch to drill-and-blast method.
- When
- Following a collapse on February 22 and after the second machine was awaiting repairs.
- Where
- Srisailam Left Bank Canal, in Nagarkurnool and Nalgonda districts, India
- Why
- Due to safety concerns following a tunnel collapse and the risk of similar incidents if the TBMs were used.
Concerns Regarding TBMs
Project completion
Safety vs. Efficiency
Concerns Regarding TBMs
Using TBMs after the collapse posed a risk.
Project completion
Continuing with the original plan of using TBMs.
- Project
- Srisailam Left Bank Canal (SLBC) Tunnel
- Method Change
- TBM to Drill-and-Blast
- Tunnel Length
- 43.94 km (total)
- Remaining Work
- Approx. 9.5 km
- Water Capacity
- 33 TMCft
- Reason for change
- Safety concerns