BBMP's proposed tunnels could be castles in the air

BBMP's proposed tunnels could be castles in the air

Rohith BR. Bangalore

There are out-of-the-box ideas that are meant never to see the light of day. The Bruhat Bangalore Mahanagara Palike (BBMP) has considered the construction of tunnel roads to ease traffic flow; the plan was discussed at a review meeting for city development works, attended by chief minister BS Yeddyurappa on Monday. However, executing the task will not be easy. In the past, similar ideas have met insurmountable hurdles.
Plans like these have been proposed in the past without the requisite background work. The state budget plan of February 2009 had an allocation for the Bangalore Development Authority (BDA) to build a tunnel road linking Hebbal flyover with the Kanteerava Stadium, along the Outer Ring Road, and passing under Tumkur Road. Such a road would help motorists avoid six busy junctions, including Tumkur Road junction, Jalahalli railway crossing junction, BEL Circle junction, and Kuvempu junction at Bhadrappa Layout. Over-ground, motorists might also have to wait at a railway crossing.
"That project never took off. We found that it was an expensive affair; defence forces and the South Western Railways protested that it would be a security risk, as the tunnel would pass through land belonging to the Air Force, and under the Jalahalli railway crossing," a senior BDA official explained.
R Srinivas, engineer member, BDA, explained that the costs of construction of a tunnel road are prohibitive: "A tunnel road would be almost five times more expensive than a flyover. One needs to dig nearly 15 metres for a road; during the construction, lighting arrangements and boring, also pumping out the water if it rains — all these require electricity." Preliminary estimates of the cost of construction of one km of tunnel road is Rs160 crore.
The biggest hurdle of all, though, is a geological one—the city sits on a bed of hard rock. Hydro-geologist N Ranganathan recalls that officials of the Bangalore Water Supply and Sewerage Board had considered micro-tunnelling as an alternative for underground reservoirs, but the plan was dropped as it was not feasible for a city that has an underlying bed of hard rock.