Using explosives might be quick, but with ever more development in crowded cities, more discreet ways of demolishing old buildings are having to be found. Of course grapples, shears and magnets will always aid in demolition of buildings but the way buildings are demolished in crowded cities are evolving. In crowded cities, there are tougher controls over demolition such as protecting adjacent buildings and reducing dust. An additional problem is that when everything tumbles into a giant heap it is difficult to extract material for recycling, now an important way of defraying demolition costs. One way to demolish buildings in cities is by blowing up a large piece of concrete and producing almost no flyrock which does not rely on a conventional explosive material. Another way to demolish building’s in cities is to “chew a building apart” from the top down such that a shear attachment can gnaw through steel columns thick enough to support a 20-storey building. An even more unusual method of demolition was first demonstrated in 2008 by Kajima, a Japanese construction company, when it took down its 20-storey and 17-storey Tokyo headquarters buildings from the bottom up.

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