Work to replace faulty bearings of the Ruby-bound ramp of the Parama flyover is scheduled to begin late on Monday, sources in the Calcutta Metropolitan Development Authority (CMDA) and police said.

The ramp would remain closed from 10pm on Monday to 6am on April 27, a police officer said.

Six bearings of the 968m-long ramp will be replaced after engineers detected “a defect in the drawing and engineering” of the ramp and suggested immediate replacement to make the ramp worthy of bearing heavy load.

This is the first time since the flyover was thrown open in 2016 that bearings are being replaced. Metro had reported on April 8 that the Parama flyover ramp going towards Ruby rotary on the EM Bypass would be closed to traffic for 12 days from the night of April 12 to allow replacement of the faulty bearings.

The diversion was deferred by a few days to complete preparatory work for the replacement, engineers and police officers said.

“The basic work of fitting angles and preparing for replacement of the bearings has been completed,” said a senior engineer of the CMDA, the agency that maintains the city’s longest flyover. “The actual replacement will start on Monday. We have sought a traffic block for a fortnight.”

A signboard about the maintenance work. Pictures by Bishwarup Dutta

Another police officer said the CMDA had been requested to block the flank only once all preparation was complete. “We requested them to first build the platform on which engineers will stand while replacement work is on. The platforms have been built and they will begin the actual replacement work from Monday,” the officer said.

The bearings would be replaced with POT PTFE ones that carry vertical load. The work will be carried out by HCC, a Mumbai-based construction company that built the flyover, including the just-opened AJC Bose Road ramp.

The bearings have reached the site, HCC sources said.

Lalbazar has been asked to make arrangements for diverting all Ruby-bound traffic from the Park Circus seven-point crossing from Monday to allow replacement work.

“Engineers from the CMDA have told us they want the block from Monday. We will divert traffic accordingly,” said an officer of the traffic police department at Lalbazar.

“The Ruby-bound traffic would be diverted from the Park Circus seven-point towards Darga Road for No. 4 Bridge down Suhrawardy

Avenue. We have put up several signage asking Ruby-bound vehicles coming from Park Circus to take the Park Circus connector instead of Parama flyover,” a police officer said.

Senior police officers said they would monitor the diversion and fine-tune it.

The change of bearings comes within three days of chief secretary Malay De meeting senior officials of the CMDA, the Calcutta Municipal Corporation, the police and the transport department. De had instructed that the survey on the health of the city’s bridges and flyovers must be completed by mid-May and repairs initiated soon.