How do tower cranes get built?

Question

Surely a crane needs something to lift its components into place so how do they build those permanent building site cranes? Can they lift them selves up?

Answer 1

A PBS video of the WTC construction using self-jacking cranes is shown at the ref. 1 site. This is part of the transcript:
In August, 1968 actual steel construction began. Kangaroo cranes imported from Australia were used for the first time in the United States. The cranes were assembled on top of the core columns. Each could lift 60 tons at a time. They would be the driving force behind the towers' construction. The cranes had the ability to jack themselves up 36 feet at a jump. As the walls grew to the height of a crane, the crane would hoist itself up, a neighboring crane would swing core columns into place beneath it, and construction would continue.
Also check out ref. 2 for some useful diagrams.

Answer 2

No. They are lifted into place in sections by one or more other cranes, the telescopic arm kind, which are either in a nearby street or on the building site. I watched several being built and then dismantled over a period of three years at a large development across the street from my house. However, I saw a TV programme about how they built one on top of a mountain, and there they used helicopters to lower the sections into place.

Answer 3

No thay use 2-3 other cranes. And when thay get 2-3 floors done thay can lift it self. I seen it the History.

Answer 4

Another crane lift the parts into place.

Answer 5

See the following site for details:

Answer 6

They hoist themselves up bit by bit adding a new section at a time, until they reach the desired height. Its very cool.

My first answer back!

Answer 7

they use another crane called the tower crane builder....

Answer 8

From the ground up, they are self raising within themselves.
Like a telescope.

Answer 9

from the top down