Guwahati: The herculean task of complete repair and restoration of the upper deck of the Saraighat rail-cum-road bridge over the Brahmaputra near Guwahati is completed and re-opened within the targeted time today. The work which started on 23rd March has been completed in just 89 days.
Almost 500 workers were engaged to carry out the technically challenging task of replacing 54 slabs on the upper deck along with replacement of 11 expansion joint slabs and expansion joints.
The methods adopted to replace 54 deck slabs and the 11 connecting expansion joints involve breaking down the concrete slabs, expansion joint slabs and removing the expansion joints. On an average 75 workers per day were engaged in breaking the slabs and 45 workers per day were engaged in carrying these broken pieces away and cleaning.
The repair and replacement of the upper deck slabs of the bridge was particularly difficult because of the fact that train movement on the lower deck was 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). Accordingly, special temporary scaffolding was 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 were laid and welded to the bridge over which high-strength concrete was 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 were ready and the expansion joints were replaced, 50 to 65 mm thick heavy-duty Semi-Dense Bituminous Concrete (SDBC) were laid over the entire deck to facilitate vehicular movement. To ease the bumps over the expansion joints, 150 mm thick aluminium plates were laid over them under the SDBC. This will make driving over the bridge comfortable even at high speed. Road markings, painting of side beams, side railing and fixing of car eyes has been done for improvement of aesthetics.
NFR has been able to adhere to the commitment given to Honourable CM, Assam for reopening of the bridge by 20th June. NFR also thanks the State Govt for all their help and the local people for their cooperation.