Kolkata: Load-bearing test starts for Dhakuria FOB

KOLKATA: Around 1,500 sacks of sand, weighing nearly 59,000kg after a shower on Saturday afternoon, were placed on the 43-metre suspended span of Dhakuria foot overbridge (FOB) to check its load-bearing capacity. The sacks will be in place for at least 24 hours with engineers taking measurements every hour to check for deformity in the steel structure before it is cleared for use by pedestrians.
The load test is being carried out following extensive repairs to the FOB that was shut down after it was declared weak and unsafe around seven months ago. "The structure had become weak and wobbly. The bridge experienced vibrations and deformity was also noticed," said bridge engineer Biswajit Som who is supervising the load test.
Kolkata Municipal Corporation had asked advertising agencies to remove all hoardings from FOBs in the aftermath of the Majerhat bridge collapse and asked them to conduct tests and furnish fitness certificate before they could again use them for advertising. The Dhakuria FOB was subsequently shut and the framework strengthened. It now needs to pass the static proof load test before a fitness certificate is issued.
The first load of 700 sacks was placed on the bridge on Saturday afternoon. Thereafetr, 400 sacks were placed an hour later, followed by 400 more another hour later.
"We placed the sacks gradually after checking that there was no deflection. Had there been a deformity after the first load was placed, we would not have put any additional load," Som explained.
Initially, the sand bags weighed 34kg each. But the gross weight increased to 39 kg after the rain. The bridge, that is 43 metre long and 2.5 metre wide, is at a height of 6.5 metre from the road surface. "The load test is meant to check the strength and stability of the bridge at full load. We apply a load of 500kg/sq m on the basis of seven-eight adults standing on each square meter of the FOB," said Som.
The FOB is used sparingly most of the year round. But usage increases dramatically during Durga Puja when the road is cordoned off. Unable to cross the street, pedestrians are forced to use the bridge.