The Tallah bridge will undergo tests to check how the structure is performing under an extra pressure of goods vehicles.
With the Santragachhi bridge shut for repairs, all goods vehicles headed to Kolkata are now being diverted along BT Road.
Senior PWD officials said with the newly-built structure exposed to goods vehicles from Santragachhi, they would conduct a series of tests to check the bridge’s performance and make necessary amends if necessary. They would look into the degree of deflection of the bridge’s deck slabs and its oscillation, two vital components of any bridge-like structure, they said.
“We will carry out a survey to see how the bridge is performing. Deflection metres and strain gauges will be fitted to take readings when goods vehicles cross the bridge and we will then sit with the results and analyse them,” said a senior PWD engineer overseeing the maintenance of the Tallah bridge, which was thrown open on September 24.
Construction experts said in engineering deflection means the bending or displacement of a beam from its original position.
When a beam is loaded, it bends and deflection metres measure the degree of displacement.
Built at an estimated Rs 540 crore, the 750-metre long Tallah bridge — with an arm towards Chitpore railway yard — connects parts of Dunlop, Baranagar, Sinthee and Chiria More to Shyambazar over the railway tracks.
The load-bearing capacity of the newly-built structure is at least 100 tonnes more than its older version.
“With goods vehicles using the bridge we want to know how the girders are responding to such heavy loads,” the engineer said.
Senior officials said apart from strain gauges, load pads would be fixed beneath the deck slab to identify the axle load of different types of vehicles.
At different points in the day and night an hourly count of vehicles will be taken. This count will be tabulated with the readings from the load pads to understand whether a vehicle crossing the bridge was a two-wheeler or a truck.
Once different loads are identified, the findings will be tabulated against the degrees of deflection.
