Preliminary work to begin soon on Namma Metro Phase 3A

Bengaluru: Namma Metro is set to begin preliminary work on Phase 3A, a mix of underground and elevated lines connecting Sarjapur in the southeast to Hebbal in the north via the city centre. 

Bangalore Metro Rail Corporation Limited (BMRCL) has floated tenders worth Rs 6.86 crore to carry out geotechnical investigations in four packages. November 3 is the last date for submitting the bids. Contractors will have 150 days from the award date to complete the work. 

Although the union government is yet to approve Phase 3A, a senior BMRCL official said that the state government's nod last December allowed them to carry out preliminary works such as geotechnical investigations and utility identification. Phase 3A's alignment is roughly the same as the controversial tunnel road project. 

The geotechnical investigation is the first stage of groundwork for building a metro line. It involves examining the physical properties of soil and rocks to determine the depth and design of foundations — for piers in the case of elevated sections and for tunnels in the case of underground stretches. 

The study also helps identify the type of Tunnel Boring Machines (TBMs) needed for tunnelling and enables contractors to estimate construction costs, another senior BMRCL official said. 

Meanwhile, French multinational Systra has submitted its report reassessing the cost estimates for Phase 3A. 

The report is under evaluation and will be sent to the Centre, which will decide whether to approve Phase 3A or suggest more changes, another senior official said. 

The BMRCL had appointed the consultant after the Centre flagged the "high" cost. 

The 36.59-km Phase 3A, also called the Red Line, is estimated to cost Rs 28,405 crore, or Rs 776.3 crore per km, the most expensive in Namma Metro's history. 

Phase 3A's tentative deadline is 2031. 

Phase 3A will run underground from Koramangala 2nd Block through the Central Business District (CBD). It will feature a double-deck viaduct (metro-cum-road) in the overground sections: Sarjapur to Iblur (14 km) and Agara to Koramangala 3rd Block (2.45 km). 

Metro soil tests

Sarjapur to Carmelaram (elevated, 9.86 km), including the depot at Sarjapur

Cost: Rs 1,91,08,960

Carmelaram to null point near Koramangala 3rd Block (elevated, 9.22 km)

Cost: Rs 1,50,66,680

Null point near Koramangala 2nd Block to KR Circle (underground, 7.695 km)

Cost: 1,36,25,612

KR Circle to Hebbal (8.816 km)

Rs 2,08,45,792