The demolition work of the Tallah bridge resumed a few days ago to ensure the 57-year-old structure is pulled down by the end of this month.

The demolition of the bridge had stopped after the Centre announced a 21-day lockdown to stop the spread of the coronavirus.

The Bengal government had set a 21-month target for the new bridge to come up from the date the site is handed over to the construction company, L&T.

Things changed a few days ago when the bridge was listed as a “critical structure” and “exempted” from the lockdown. “We have resumed work of demolishing the spans that stand over the rail tracks following the guidelines of social distancing,” a PWD engineer overseeing the demolition work said.

A team of 20 engineers and workers has been readied and split into three shifts to carry out the demolition with the help of a jaw-crusher machine and diamond cutters. The number is almost three times less than the normal count, the engineer said.

Every team member has been allocated a room and all have been provided with masks and gloves. Sanitisers have been kept at the work site as well as at the quarters. Meetings with senior engineers are being held on various social media platforms.

Engineers have been asked to videoconference with their superiors for any clarification and to give them daily updates, a PWD official said.

The challenge lies in pulling down the slabs over the tracks. There are eight such concrete spans, each measuring about 25m in length and 12m in width. The railways has to ensure there is no movement of goods trains when the slabs are pulled down.

“The railways has organised for a complete power block since movement of goods, particularly cement and salt, has been stopped because of the lockdown,” a rail official said.

A PWD engineer said by April 14 the entire stretch of the bridge over the tracks would be pulled down. In another fortnight the two approaches would be demolished. “We plan to hand over the site to the construction company that will build the new bridge by the first week of May.”

The Telegraph had earlier reported about a jaw-crusher machine that has been requisitioned for the job. The jaw-crusher slips concrete chunks within its jaws after ripping them off and crushes them into dust.

On Monday, the jaw-crusher machine was in action as it ripped apart concrete spans over the tracks.

The company, L&T, will start building the new bridge once the site is handed over to the company, an official in Nabanna said.

The old bridge was written off after a government-appointed committee running a health check on bridges and flyovers in the city concluded the structure was unfit to bear vehicular load and had to be demolished.

The proposed bridge will have a 24m wide deck - 5.5m more than the existing one. The existing pillars will have to be pulled down and new ones built to bear the load of wider decks, a PWD engineer said.

The new Tallah bridge will have a carrying capacity of more than 350 tonnes - 100 tonnes more than the old structure.