500 people working round the clock sans disrupting train services
GUWAHATI: The herculean task of completion of repair and restoration of the upper deck of the Saraighat rail-cum-road bridge over the Brahmaputra here is nearing completion and is likely to be reopened within the targeted time.
Almost 500 workers are engaged to carry out the technically challenging task of replacing all the 54 slabs on the entire upper deck along with replacement of 11 expansion joints over the pillars are progressing as planned, according to NF Railway sources here.
Fifty-four deck slabs and the 11 connecting expansion joints were badly damaged and the methods adopted to replace them involve breaking down the concrete slabs, expansion joint slabs and removing the expansion joints. On an average 75 workers per day are engaged in breaking the slabs and 45 workers per day are engaged in carrying these broken pieces away and cleaning.
The repair and replacement of the upper deck slabs of the bridge is particularly difficult because of the fact that train movement on the lower deck is continuing without any disruption. For this, special permission had been obtained from Commissioner of Railway Safety (who works under the Ministry of Civil Aviation to maintain autonomy), by providing guarantee that specific care would be taken to ensure that no debris from the Upper Deck falls on the Lower Deck of the bridge. Accordingly, special temporary scaffolding has been erected under the Upper Deck to collect broken pieces from the deck.
After breaking down of the old concrete slabs and the expansion joint slabs, fresh 10mm thick steel plates are laid and welded to the bridge over which high-strength concrete is being laid to make the deck slabs. More than 500 tonnes of steel plate and reinforcement rods have been used for the deck slabs alone.
Once, the deck-slabs are ready and the expansion joints are replaced, 50 to 65 mm thick heavy-duty Semi-Dense Bituminous Concrete (SDBC) will be laid over the entire deck to facilitate vehicular movement. To ease the bumps over the expansion joints, 150 mm thick aluminium plates will be laid over them under the SDBC. This will make driving over the bridge comfortable even at high speed.
The work has been progressing very well without any major traffic disruption because of the co-operation of the people and the civil administration. N. F. railway is hopeful of completing the work within the target date of June 20, 2019.