How many tower cranes are there?

27 May 2008

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A journalist telephoned me the other week to ask if it was true that 10% of the world's tower cranes are in Dubai.

Unfortunately this popular myth will simply not die. The quick answer is that the population of the UAE is tiny in comparison to the crane stock, which is not actually that big compared to some larger European markets. So the place feels like a forest of tower cranes, but it is not that big in a global context.

The question assumes that there exists somewhere a total number of tower cranes in the world. This is false.

There are two problems with this idea. First, tower cranes are modular, so the number of mast sections in a tower, and a jib, depends on the job - how high the building is going to be, and how long a reach you need.

I think that this fact is a big problem for those who want to write a national register of tower cranes. Every company that has more than one tower crane mixes up the sections in the yard. Every time the crane is erected it is effectively a new machine, because it is a new, and probably unique, combination of different parts.

But even if we agreed on some average number of sections in a tower crane, this number would still not be right. No two companies would ever retire a tower crane at the same time. This complex decision depends on the state of supply, demand, the mix of jobs and client requirements.

Most companies get rid of tower cranes by selling them on the used market. Neither they, nor any other vendor, would necessarily sell all of the sections that originally came with the crane. And how many times do tower cranes get sold on the used market? In our international times, noone tracks how far down the river they may travel: Angola, Haiti, Cambodia, Dubai. Where does a crane go to die?