IISc scientists build subway using unique technique

BANGALORE, AUG 18: A team of scientists from the Indian Institute of Science IISc's department of civil engineering has built a subway c...

BANGALORE, AUG 18: A team of scientists from the Indian Institute of Science IISc8217;s department of civil engineering has built a subway connecting two parts of its campus using a unique technique that would well teach city corporations in the country how to go about it without disrupting the traffic.

The team led by Prof B R Srinivas Murthy of civil engineering department took just about a year connecting the two parts of the IISC campus the Centre for Scientific and Industrial Consultancy-ASTRA campus on one hand and the Genetic Department side of the main campus on the other which were separated by C V Raman Road.

The heavy traffic on this road linking two major highways had taken away several lives, four of them being staff members of this premier institution.

The project, which is a typical example of the proverbial quot;necessity is the mother of inventionsquot;, involved pushing a pre-fabricated concrete block horizontally into the wall of soil by the side of the road where the tunnel was intended 8211; a technique called box jacking method. This technique was supported by another called soil nailing to prevent any collapse of the eroded area.

According to Prof Murthy, the pre-fabricated concrete block was rested against a strengthened wall supported horizontally in between by a hydraulic jack used for pusing the concrete block attached with 45 cms cutters into the vertical wall of soil ahead.

The beginning of this process was made by digging a trench four metres in depth, eight metres in length and six metres in width to accommodate the concrete block and the hydraulic jack on base railings like railway tracks.

A sufficient dent was made into the wall ahead using simple tools used commonly by labourers, and iron rods were inserted into the ceiling of this dent soil nailing to avoid any collapse caused by the heavy traffic above.

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The subsequent progress made by the concrete block was followed by inserting several more iron rods into the sides and ceiling of the tunnel that was taking shape. The process was carried on till the concrete block emerged from the other side below the main road, without disrupting the heavy traffic above.

Prof Murthy said this technique yielded twin benefits of low-cost and avoiding disrupting the traffic. Many sub-way projects undertaken by corporations take ages apart from causing severe traffic jams at critical junctions of the city, he said.

However, according to Murthy, a near disaster was averted during the project work when the concrete block gradually started tilting upwards and came dangerously close to a massive Bangalore Water Supply and Sewerage Board8217;s BWSSB pipeline supplying several thousand tonnes of water from the Yelahanka area to the city.

quot;Had we not noticed this seemingly small flaw a major disaster would have occurred causing flooding and several lives being lost in the bargain,quot; he explained.

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But this was corrected with the help of the BWSSB personnel who co-operated by attaching a by-pass pipeline to avoid any damage. The two-way subway, which was opened on the eve of the 53th Independence Day that was just celebrated, is 20 metres in length and primarily meant for light motor vechicles and two-wheelers.