Metro's underground work bogged down by clay

Oct 04, 2011, 07:02 IST | Johnlee Abraham

BMRCL to procure machines from China and Italy by mid-2012 as tricky soil conditions stalls work on 4.4km stretch

BMRCL to procure machines from China and Italy by mid-2012 as tricky soil conditions stalls work on 4.4km stretch

Even as the Metro is gearing up for the October 20 launch of its first leg, the underground section of the mass transit system seems have hit a roadblock.
Work is now unlikely to start before June 2012, courtesy tricky soil condition on the 4.4-km stretch.

Construction at the underground section of the Metro
is unlikely to commence before June next year

According to an official from the Bangalore Metro Rail Corporation Limited (BMRCL),  a new set of machines have been ordered from Italy and China, which will arrive only by mid-2012.

The decision was taken as certain parts (4.4-km) of the 24.20-km North-South corridor from Hessaraghatta to Puttenhalli has softer soil, mainly clay, for which an Earth Pressure Balance Machine (EPBM) has to be specially used.

Soil to blame
At present, the BMRCL underground work is in progress at the Majestic station, but pace is considerably slow due to the presence of boulders.

"We now have to bring these specialised machines as the soil condition of the area is very complicated.

The Chikpet and City Market area is densely populated, and the soil contains clay. EPBM are being brought in to ensure that work progresses faster," said a BMRCL official.

He added that condition of soil is not the only problem. High water table and old buildings dotting the stretch are making tunneling work very difficult in Chikpet.

The soil condition in the city is mainly classified as clay, silt, sand, gravel, cobbles and boulders.
Based on these soil types, various tunnel boring machines, such as TBM with slurry shield, have been brought in. However, the EPBM are yet to be deployed.

Delay unavoidable
Owing to several factors, the delay seems unavoidable. MiD DAY had earlier reported that the Bangalore Metro underground section of the Phase I will be operational only by 2014.

Though the BMRCL had initially claimed that the entire 42.3 km stretch of Phase I will be commissioned by
2012, it had then backtracked and stated that the launch would happen in 2013.

Now, to begin the tunneling work on the North South section, BMRCL will have to get the machines from Italy and China, but that will only happen by mid 2012, after which they will have to assembled.

Game changer

BMRCL is now trying to play down the issue and has said that the work progress is smooth.

"These machines are for the N-S section and we have already deployed two similar machines. Another three machines will definitely help to speedup the work," said B L Y Chavan, spokesperson BMRCL.

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