By Lindsay Gale02 July 2008
Some elements of the building stood 62 m (204 ft) tall, and it was located at a busy city-centre road junction. To compound the problem, parts of the building stood over a railway tunnel that ran underneath the basement.
The use of a traditional wrecking ball and mobile crane was ruled out because that would have required the closure of the roads. A high-reach excavator with sufficient height to reach the top of the building was not available, and other methods, such as demolition by hand, were deemed to be overly expensive.
As a result, it was decided to use explosive demolition, despite the difficulties of the site and the presence of the tunnel, since this offered a quick and sure solution.
The blast concept that was developed by structural engineer Dr Rainer Melzer provided for a "zig-zag folding" of the building onto its footprint, avoiding potential damage to surrounding structures.
To prepare for the demolition, high reach excavators were brought on site to demolish those parts of the building that they could reach, and soft strip was carried out on the main structure. It was then prepared for demolition.
● For a full site report, see the forthcoming July-August edition of D&Ri magazine.
Demolition contractors: Sticker, Prangenberg & Zaum and Heitkam Umweittechnik.
Blast design: Dr Melzer
Blast contractor: Thueringer Sprenggesellschaft
Building owner: Volkswohl Bund Versicherungen