The Daruma-otoshi demolition system was invented by the Japanese construction company, Kajima Corporation.
This technology to demolish skyscrapers consists in replacing the support columns with gigant computer controlled hydraulic jacks. Then, the first floor is demolished and the debris is taken out. Next, the entire building is lowered down with the hydraulic jacks and the demolition of the second floor begins...till the end when the last floor is demolished.
The method is called daruma-otoshi, because of an old Japanese game called that way. It consists of hitting a Daruma doll (composed of 5 pieces one on top of each other) using a small hummer, from bottom to top, avoiding the pieces from falling during the whole game. The Daruma-otoshi japanese video game is available here.
Video: Daruma-otoshi demolition method used in floors 17 and 20 of buildings in Tokyo, Japan.
- City center buildings can be demolished without interrupting the traffic.
- Too much space is not needed to collect debris, because it is taken out all the time.
- The recycling process is more effective: 99% of steel and concrete and 92% of the interior materials.
- No need for explosives.
- The demolition is better controlled and safer.
- Less noise is produced.
- It's 20% faster.
- I suppose that it must be more expensive.
From: youtube, wikipedia