Tunnel Boring Machine Bhadra emerges out of the Kadugondanahalli (KG Halli) metro station on the Pink Line on Thursday.
Credit: DH Photo/Pushkar V
Bengaluru: More than 91 per cent of tunnelling has been completed on Namma Metro's longest underground section, which is slated to open in 2025.
A thunderous applause swept through the KG Halli metro station as Tunnel Boring Machine (TBM) Bhadra emerged at 6.08 pm on Thursday.
The German-made Herrenknecht EPB machine (S-840B) bored a 1,186-metre, northbound tunnel from Venkateshpura to KG Halli in 357 days, or 3.3 metres per day on average. This was the second tunnel bored by Bhadra and the 22nd of the total 24 on the Pink Line.
Bhadra's breakthrough was witnessed by Deputy Chief Minister D K Shivakumar, who has championed the building of tunnel roads to address Bengaluru's traffic problem.
Shivakumar stated as much. "We have planned tunnel roads in Bengaluru. I am here to get a first-hand understanding of tunnel drilling and its challenges,” he told reporters.
Replying to a question from DH, Shivakumar said the government was sparing no effort to expedite the metro work. However, he didn't specify if the Pink Link would open in March 2025, the existing deadline. "The line will open in 2025," he said.
The 21.26-km Pink Line, which will connect Kalena Agrahara to Nagavara, has a 13.76-km underground section and a 7.5-km elevated section. The underground section involves constructing 20.992-km twin tunnels. The construction of 18 stations (12 underground, six elevated) is 75% complete.
Bangalore Metro Rail Corporation Limited (BMRCL) deployed nine TMBs to construct the tunnels. Seven of them (Urja, Varada, Avni, Lavi, Vindhya, Vamika and Rudra) have finished their job.
The eighth one, Tunga, embarked on its final drive (KG Halli-Nagavara, 935 metres) on February 2.
Bhadra was the ninth machine. After Thursday's breakthrough, it will be relaunched for its final assignment — a 939-metre northbound tunnel from KG Halli to Nagavara — on April 7, 2024.
An executive of ITD Cementation Limited, which is building the 4.591-km underground metro line from Tannery Road to Nagavara, said Bhadra's relaunch would take anywhere between 30 and 60 days depending on the amount of welding needed for its cutter head.
While the BMRCL said Tunga and Bhadra would complete their final tunnelling drives in August, December seems more realistic.
A senior BMRCL official said the geology in the KG Halli-Nagavara section comprised a mix of weathered rock and sandy silt/clayey sand, making it relatively easier to tunnel, but added that nothing could be said with certainty about Bengaluru's soil profile.
"Some of our TBMs tunnelled 200 metres a month while Bhadra averaged only 100," the official said.
'Bengaluru metro better than the one in Delhi'
Deputy Chief Minister DK Shivakumar said Namma Metro was better than the Delhi Metro because "we never compromised on quality".
On the airport line, he said land acquisition was 98% complete, civil work 53% and the construction of 17 stations was going on.
Shivakumar said all future metro lines in Bengaluru would have two-level viaducts — one for the road and the other for the metro. "The BBMP will bear the flyover cost, while the BMRCL will fund the metro work. I have seen such projects in Nagpur."
Kamaraj Road to reopen in April
The Kamaraj Road stretch connecting Cubbon Road and MG Road will reopen for traffic in April. It was closed in 2019 for the construction of the underground MG Road metro station.
Feasibility studies for new lines
Workers at the construction site of the Kadugondanahalli (KG Halli) metro station on the Pink Line on Thursday.
Credit: DH PHOTO/PUSHKAR V
Feasibility studies are underway for extending the metro to Anekal, Tumakuru Road and Bidadi. "I will give details once the reports are ready. We have to consult the Centre before announcing new lines," Shivakumar said, when asked if the government would announce new lines in the upcoming state budget.