The Tallah bridge will be closed to traffic from the midnight of January 31 for demolition, it was decided at a meeting joined by several agencies at Nabanna on Friday.

“Dismantling will start on February 1, from the Shyambazar-end,” said an official of the public works department.

The 57-year-old north Calcutta bridge came under the scanner for its failing strength. Engineers concluded after several rounds of inspection that the structure might collapse any moment, prompting the government to decide to pull down the bridge and build a new one.

The government had on September 29 announced a ban on the movement of buses, lorries and other heavy vehicles on the bridge. Smaller vehicles are allowed but their speed cannot exceed 10kmph.

It was earlier decided that the structure would be razed from January 4 but the schedule had to be deferred after it appeared that a level crossing on the railway tracks below the bridge was vital to ensure smooth diversion of traffic.

“The railways have agreed to complete the work of constructing the level crossing by the end of this month. The state government has paid the railways Rs 14 crore for the work,” said a Calcutta police officer involved in drawing up plans for traffic realignment around the Tallah bridge.

Demolition will take around three months, officials said. PWD has decided to put into service jaw-crushers and diamond cutters to expedite the process.

Primarily it has been decided that construction of the new bridge would begin in June. The new bridge will be about 6m wider than the existing one. Its load-bearing capacity would be close to 400 tonnes, compared with 250 tonnes of the existing bridge. The new bridge will come up at a cost of around Rs 350 crore.

Calcutta police have firmed up a diversion plan wherein buses bound for BT Road from south would be allowed to take the Chitpore-Lockgate flyover.

“Now, the one-way traffic rule allows small vehicles to move towards Central Avenue from BT Road till 1pm. If buses are allowed, they will move in the opposite direction on a dedicated flank on the flyover,” said an officer. “But that will not impact the one-way rule for other vehicles.”

Buses headed towards Shyambazar would be diverted through Dum Dum Road, Northern Avenue and Belgachhia. Police sources said the auto routes would be realigned to ensure a greater number of passengers reach Dum Dum and Noapara Metro stations.