Kolkata, India (BBN)-In August, a barge will start from Kolkata with a special consignment for Bangladesh. It will be a 102.4-metre span of the second Bhairab railway bridge across River Meghna.
Eight more spans will follow and the bridge will be completed within the first half of 2016. This double-line bridge, being constructed by India as part of the $1 billion line of credit to Bangladesh, will be an important link in the Dhaka-Chittagong rail route, reports The Times of India.
"The company has also been selected for a project in Sri Lanka. The Bhairab rail bridge will connect Ashuganj in Brahmanbaria, close to Bangladesh's border with Tripura, and Bhairab Bazaar.
As it is part of the line of credit, only Indian firms were allowed to participate in the tendering process. The contract was bagged by a joint venture between IRCON International and AFCONS Infrastructure Ltd.
Texmaco Rail and Engineering Ltd got the order to build the bridge's infrastructure. Texmaco is also building a bridge across River Titas in Bangladesh," said Dulal C Mitra, senior vice president (infrastructure), Texmaco Rail and Engineering Ltd.
The 1.02 km-long bridge is expected to cost nearly Rs 5 billion. The spans will be erected using the cantilever method.
The first span underwent 'trial assembly' inside Texmaco's premises on B T Road.
This involved constructing the entire span and then measuring the sag due to the weight of the superstructure. The span is constructed on concrete piles at either end.
Removable jocks hold it up in the middle portion. After construction, the jocks are removed and the span is allowed to hang free.
This is when a superstructure sags. If the sag is within limits set by structural engineers, the span is ready otherwise it's back to the drawing board.
According to Mitra, the sag was well within permissible limits and cleared inspection.
The assembled girder will be dismantled and sent to Bangladesh.
"The overall width of the bridge will be 6.24 metres with an overall height of 13.275 metres (equivalent to a four-storied building). The weight of each girder is 780 tonnes. It was no easy task.
The weight of the heaviest component of the span was 14 tonnes.
We used cranes of 40 tonnes capacity to bring the components to place.
Fabrication and erection of the spans are intricate and require precision workmanship.
Each girder requires 1.5 lakh holes to be drilled. This means that 14 lakh holes will have to be drilled for the nine girders.
Each girder will also require 17 km of single run welding. The total welding required will be 153 km and this has to be completed in the next nine months," Mitra added.
There are two existing bridges across the Meghna.
One of these is a single-line railway bridge and the other is for road transport. Bangladesh railway minister Mujibul Haque recently said: "The Bhairab and Titas railway bridges are being built with the Indian Line of Credit. The effort is to upgrade the 320km Dhaka-Chittagong railway corridor to double lines, of which work on a 124km stretch has been completed."
BBN/SK/AD