If you thought building a huge bridge across the Netravathi, parallel to the existing one near Jeppinamogaru will take years, you may be wrong. Thanks to advanced technology and a modern crane being put to use in this region for the first time in bridge construction, it could be ready much sooner than expected.
To save time, the builders on Monday began using the pre-cast concrete girders and began placing them on pillars with the help of an imported hydraulic gantry crane (also known as hydraulically operated pre-cast girder launcher).
Navayuga Udupi Tollway Pvt. Ltd. (NUTPL) is building the bridge on the National Highway No. 66 (formerly NH 17).
A girder is a support beam placed horizontally on the pillars of the bridge before laying slabs over it for making the road. The length of each girder is about 32 metres to 45 metres. As many as 96 such girders will be placed atop the pillars to complete the 804-metre bridge.
Two engineers, a Malaysian and a Chinese, were on the spot on Monday specifically to supervise the mechanised placing of pre-cast girders.
The NUTPL was building the bridge for the National Highways Authority of India (NHAI) as part of widening the 90-km stretch on the NH 66 between Kundapur and Surathkal and from Nanthoor Junction and Talapady into four lanes.
Prashanth N. Gawasane, Project Director, NHAI, Mangalore, told The Hindu that using pre-cast concrete girders and placing them using a girder launcher saved time. It added to the strength of the bridge, he said.
Manual construction of concrete girders consumed more time as the beams required erecting more supporting system in river water and would cost more, Mr. Gawasane said.
Sanjeev Kumar Singh, Project Manager (Structure), Navayuga Engineering Company Ltd., said it would take more than two years to build 96 girders if it was done in the traditional way. Laying slabs and making the road would require some more time. With the modern technology, the bridge could be completed within that period. He said the company would place two pre-cast girders a day on the pillars from Tuesday.
Each pre-cast concrete girder weighed over 100 tonnes. The hydraulic gantry crane used in the project had the capacity to lift a pre-cast concrete girder weighing up to 150 tonnes, Mr. Singh said.
He said that 12 to 16 pre-cast concrete girders could be made in a month. In addition to the one placed on the pillars on Monday, 20 pre-cast girders were now ready to be placed. He said that all the 96 pre-cast girders would be placed on the pillars before June 2012.
Mr. Singh said nine major bridges, five minor bridges, two flyovers, and a railway bridge would be built under the project. Those structures required 321 pre-cast girders of which 50 had been cast so far.