|Vidyasagar Setu in Calcutta
The first detailed inspection of Vidyasagar Setu since it was opened to traffic 21 years ago is underway. The survey is being conducted by a team that includes experts from Schlaich Bergermann and Partner, the German company that designed the 873m-long bridge, and Besu.
Under the scanner are the carriageway of the bridge, underbelly, four 17m-high foundation pillars resting in wells dug 30m into the river bed, bearings and the two approaches.
“We have recommended changing the bearings as part of maintenance,” said professor Saibal Ghosh of Besu’s civil engineering department, a member of the team conducting the survey.
“Even the wells in which the foundation pillars stand will be checked to find out if there has been any damage to the pillars.”
The longest cable-stayed bridge in India, which the chief minister will use at least twice a day once the secretariat is shifted to the HRBC building in Howrah, was constructed by a consortium of Indian PSUs, including Braithwaite, Burn and Jessop.
The construction, which took over 22 years, was supervised by engineers from two companies — Freeman Fox & Partners and Bharat Bhari Udyog Nigam Limited.
It was opened on October 10, 1992.
“As with any bridge, the first overall check-up has taken up a long time after it became operational. As the structure gets older, such scans have to be more frequent,” said Dipankar Pal, a senior civil engineer of CES, a consulting firm that is also part of the expert panel.
“There can’t be any general rule for launching a comprehensive repair or maintenance. There are several parts of a bridge — like the bearing atop the pylon or the cables — that need to be checked periodically. I don’t know if there has been any assessment of the condition of the deck below the toll plaza where very heavy vehicles hit speed breakers and jump,” said Arup Guha Niyogi of Jadavpur University, who is not associated with the survey.
Senior officials of the HRBC, the custodian of the bridge, said the bridge had been maintained regularly, but only a certain section of it at a time.
“This is the first comprehensive survey of the health of the entire bridge,” said an official.
|Repairs underway on Vidyasagar Setu.
Picture by Amit Datta
The Indian Road Congress manual has classified bridge upkeep into three types — regular check (preferably twice a year, before and after the monsoon), principal inspection (once in three years) and special inspection (followed by a major accident or earthquake).
“We have been conducting annual maintenance... the need for a holistic survey was felt after a team of experts, including engineers from Besu, opined that the cables needed a closer examination. It was necessary to check the anti-corrosive material embedded in the cables,” said a senior HRBC engineer.
Officials involved in the bridge’s upkeep said engineers had already made several rounds under the belly of the main bridge.
“We want to check the condition of the steel structure below the deck slab and see whether it has suffered any wear and tear. This is as important for proper maintenance of the bridge as checking the foundations on which the main pillars are built,” said S.R. Banerjee, the HRBC vice-chairman.