Vidyasagar Setu will remain shut to traffic from 11.50pm on April 29 to 6am the next day and again from 11pm on April 30 to 5am the next day to facilitate a “taut string test” of the bridge’s cables in “no-traffic condition,” police said.

The bridge, which has been in use since 1992, handles close to 90,000 vehicles every day.

Officials said the vehicle count on the bridge has been increasing steadily since the state secretariat was shifted to Nabanna from the Writers’ Buildings in 2013, after Mamata Banerjee took over as chief minister.

“We have selected the nights of Saturday and Sunday for the closure because traffic then remains thin. After 5am on Monday, which is May Day, the bridge will be open for regular traffic movements,” said a senior officer of Calcutta police.

During the time when the bridge will remain shut, vehicles headed for the bridge from the Alipore zoo and from Red Road will be diverted towards the Hastings crossing, from where they will move through Strand Road on their way to the Howrah bridge, the police said.

Goods vehicles headed for the bridge will be diverted towards Dufferin Road, Mayo Road and Central Avenue.