The Bruhat Bengaluru Mahanagara Palike (BBMP) determined that building twin tube tunnels is more suitable than single tube tunnels for the high-density north-south and east-west corridors in Bengaluru.
New Delhi-based Althinok Consulting Engineering Inc. arrived at this conclusion after conducting a Rs 5.54 crore feasibility study.
The BBMP awarded Rs 200 crore after the state budget to create a preliminary project report titled “Brand Bengaluru: Sugam Sanchar Bengaluru”.
According to the BBMP feasibility report, the average traffic speed in the city has come down to 15 km/h.
According to a Deccan Herald report, the three-lane twin-tube tunnels along the North-South Corridor (Hebbal Junction to Silk Board) will cost around Rs 12,690 crore. Conversely, a single tube tunnel over the same distance will cost Rs 11,065 crore.
The total length of the tunnel is 24.5 km, of which the project covers 18.5 km. The cost of twin tubes per km is estimated to be Rs 600 crore.
The BBMP plans to start work on this route after the tender is issued. The estimated cost of a twin tube tunnel for the east-west high-density corridor (30 km from K R Puram to Mysuru Road) is Rs 18,000 crore. The estimated cost of both corridors covering a 54.5 km stretch will be Rs 32,700 crore.
A senior BBMP official said twin tube tunnels are better in terms of safety and traffic flow, though single tube tunnels are less expensive.
“A single tube tunnel has been constructed in Turkey, but it is only 600 meters long,” the official said. “A single tube is not feasible in the 18.5-km length of the North-South corridor. More intersections and ramps will be required.”
The design of the North-South corridor will have an entry ramp towards the Silk Board and an exit ramp from the Silk Board. Tube 1 will have entry ramps from Chalukya Circle and CAR Circle in the same corridor.
The second entry from ramp tube 1 will reach tube 2. Exits from Hebbal and Silk Board will be in ramp tube 2. Tube 1 will be connected from Hebbal towards Dairy Circle.
