Traffic police have drawn up a detailed diversion plan for three days this week when Aurobindo Setu will be closed to traffic.

Starting 11.30pm on August 22, all Sovabazar-bound small vehicles and autorickshaws going towards the Khanna crossing would be diverted from the eastern end of Aurobindo Setu — which connects Ultadanga and Gouribari in north Calcutta — via Kabirajbagan Lane, Canal East Road, Canal West Road, Nirad Bihari Mallick Street, Raja Dinendra Street, Aurobindo Sarani and the Khanna crossing.

Ultadanga-bound small vehicles taking Ultadanga Main Road and Aurobindo Setu for the Hudco crossing would be diverted from the Ultadanga Main Road and RD Street crossing via RD Street, Ultadanga Road, Canal West Road, Canal East Road, Arif Road to reach Ultadanga Main Road and the Hudco crossing.

“Over the past few days, we have held several rounds of discussions before firming up an elaborate diversion plan,” said an officer of the Ultadanga traffic guard. “We will meet bus and minibus operators and explain the new routes.”

Normal traffic movement is expected to resume at 11pm on August 25.

Engineers of the Calcutta Metropolitan Development Authority (CMDA), which maintains the 43-year-old flyover, said it was crucial to draw up a repair plan for the flyover, which had been flagged red by RITES, an engineering consultancy company engaged by the urban development department to monitor the health of flyovers and bridges across the city.

During an inspection of the flyover earlier this year, RITES had pointed out that the bearings on which Aurobindo Setu rests should have been replaced every 10 to 15 years.

Structural and civil engineers said the reinforced concrete structure of a bridge or flyover can last decades with regular maintenance. In Calcutta, concrete structures with a high load factor show signs of stress in 25 to 27 years because of little or no maintenance.