With the initiation of the demolition work of the BGMEA building from yesterday, the topic of an efficient building demolition technique has again come to the fore. But the country still has not adopted any efficient high-rise demolition technique or formed any demolition cell, though the skyline of its cities, especially that of the capital, is being dotted with an increasing number of skyscrapers.

Owing to this lack of proper demolition techniques, 16 labourers had died during the manual demolition of the Rangs Bhaban in 2008. Despite such a tragic accident, the Rajdhani Unnayan Kortipokkho (Rajuk)—the capital’s development authority—has opted for manual demolition of the BGMEA building.  The Four Star Group bagged the demolition job through an open tender by bidding Tk. 1.02 crore for the work.

According to the Bangladesh National Building Code (BNBC), all demolition works must be done with the approval of the engineering division of the city authority or an engineering firm 'having experience in the demolition of a similar magnitude’. The 1993 BNBC, which is now being amended, also requires a detailed survey of the building to be demolished and its surrounding buildings by competent people. But the country does not have such engineering firms and RAJUK has little expertise and experience in this field.

RAJUK chairman Sultan Ahmed admitted that it does not have any efficient high-rise demolition tools or techniques in its repertoire yet. In its mechanical division, it does have impact hammers that can demolish concrete structures of up to 40 feet, he said.

He said that during the time of demolition of the Rangs Bhaban in 2008, RAJUK bought a diamond blade from Switzerland, which can cut concrete fast. But apart from that, it does not have any other tools to demolish high-rise structures. But, he said, that the experts of Bangladesh University of Engineering and Technology (BUET), who were hired and consulted during the Rangs Bhaban demolition, now have the expertise to carry out demolition of such a magnitude.

Talking with The Independent, Dr Md Alee Murtuza, former vice-chancellor and professor of civil engineering of BUET, said that the demolition of the BGMEA building would be much easier than Rangs Bhaban because of its location. Rangs Bhaban was the first high-rise to be demolished in the country. At that time, no one was quite certain about the most effective demolition process to be followed, said Dr Murtuza, who was

the team leader of experts in that demolition project.

He also said that one efficient technique is known as ‘implosion’, which involves the strategic placing of explosive materials and timing the detonation so that a structure collapses inwards. This technique could be used in demolishing large structures like the BGMEA building.

“The problem with implosion is that the technique is known to only a few engineering firms in the world. During the demolition of Rangs Bhaban, we contacted one such firm, but they charged Tk. 8 crore, which was too expensive,” he added.

Dr Murtuza said that because of the location of the BGMEA building, it could be demolished even with the traditional manual method. “Rangs Bhaban was located in a crowded area, so we had to consider the fact of physical damage to its immediate surroundings. But the BGMEA building doesn’t have that problem,” he added.  

He further said that the RAJUK now had a diamond blade, which was bought in 2008 as per the suggestion of BUET. “With the help of the diamond blade, concrete structures can be cut into a suitable portions and removed safely, provided there is planned engineering supervision,” he explained.

Meanwhile, Dr Mehedi Ahmed Ansari, project director of the Bangladesh Network Office for Urban Safety (BNUS) under BUET, told The Independent that small structures are pulled down either manually or mechanically with the help of large hydraulic equipment like-elevated work platforms, cranes, excavators and bulldozers.

He said that during the Rangs Bhaban demolition, there was a time constraint since the caretaker government wanted to open the link road by December 16, 2008. If there is no time constraint, then a better approach to demolition would be the demolition of a building with the goal of minimising the amount of materials going into landfills, he added.

He also said that the deconstruction or this ‘green’ approach to building demolition could be applied to high-rise structures, but the process was very slow. This approach involves the removal of materials according to their types and their segregation for reuse or recycling, he added.

IK