How Do Cranes Get To The Top Of Skyscrapers - Part 2

Continuing from part 1...

Internal Climbing Method. The second method used at the construction site for raising the tower crane is the internal climbing method. Here the crane, from the beginning of the construction process, is actually placed in the center of the building from where it constructs the skyscraper. As the floors are constructed, the crane is raised along with the construction of the floors from the inside of the building. The internal climbing method generally relies on the construction of the floors. One hydraulic cylinder is placed at the crane base, and this cylinder elevates the crane tower through the building in order to reach a higher floor. Later the construction workers slide steel beams beneath the tower crane to give it a stable footing and the crane begins to rise. But this climbing method requires more time for assembling when compared with the external climbing method. The external and the internal climbing method are mostly applied in the construction of skyscrapers. For example, the World Trade Centers in New York were built by implementing the internal or the external climbing method.

Heavy Lift Helicopter Or Skycrane. The third and the last climbing method involves the use of a heavy lift helicopter or shortly known as a skycrane. The skycrane picks up and lifts crane segments from the ground and moves them to the top of the skyscraper. It is not strange to see a helicopter bringing crane segments at the top of the skyscraper. This is done segment by segment, because the crane segments can have weight up to several tons. But however this method can be very expensive because it requires and involves additional equipment and extra labor effort. And because flying with heavy helicopters above populated areas is very difficult, this method is not widely adopted and it is used only for special construction projects located away from urban areas or for construction works on water.

Bonus Explanation: How Cranes Get Back On The Ground?

Once the construction of the skyscraper is completed, the tower crane needs to be dismantled, literally piece by piece. The process of bringing down the tower crane is opposite to the process of raising the crane. Most of the cranes are designed to be easily dismantled once the construction process is finished. Generally the tower crane hoist up one smaller crane which is paced at the top of the skyscraper. This additional smaller crane is known as derrick. The derrick is used at the rooftop to dismantle the tower crane into smaller parts that can be easily lowered to the ground. A third much smaller crane can be used to dismantle the derrick into smaller pieces. The third crane usually is dismantled by the workers piece by piece, and each piece is small enough to be carried by hands and transported to the ground by the elevators.