In November 2021, the Salzbach Viaduct in Wiesbaden, which was in danger of collapsing, was blown up. The colossus was brought down with 221 kilograms of explosives. Blasting master Eduard Reisch and his Reisch Sprengtechnik GmbH from Peißenberg in Upper Bavaria had planned the blasting down to the smallest detail for months.
On November 6th at 12:01 p.m. things happened very quickly, the spectacle was over in a few moments, everything went according to plan. Blasts of this magnitude are a rarity, even for Reisch. In 2014, the company caused a stir when it brought down Frankfurt University’s AfE tower in a densely built-up area; it was the largest building demolition in Europe at the time.
Different buildings require different approaches, says Reisch. “You build it up the way you build it down.” The demolition is then the condensing of months-long processes in a few seconds. The challenge is what still appeals to him so much about this job after more than 36 years, says the managing director. The sixty-year-old says he already knew when he was five that he wanted to take up this profession. Already as a child he was active with self-laboratory work, which was not always entirely certain.
Reisch remembers planning the demolition of the AfE tower. When he first got to the top of the tower and looked down, he wondered if it was possible to blow it up. “The tower should be placed in this limited space without damaging the adjacent dense development in any way,” says Reisch, describing the challenge. Up until the day of the blast, more than 30 blasters were working on the project.
Demolition work also by hand
Founded in 1985, Reisch’s company is active around the world in blasting, demolition and pyrotechnics. According to Rosita Kandlhofer, a blast is scheduled every week. According to its own statements, it is the market leader in Germany; with the long experience of Eduard Reisch you stand out from the competition. The turnover of the company, which employs 30 people, was in the mid seven-digit range in 2021. According to Kandlhofer, the profit had increased again compared to the already good year 2020.
The turnover is mainly generated with blasting work. In addition to building, chimney and bridge blasting, demolition blasting for tunnel and road construction and extraction blasting for quarries are also offered. The company also offers manual demolition work where blasting is out of the question. Other products include pyrotechnics and large fireworks for weddings and company celebrations, as well as hydraulic hoses and special parts made of steel for construction machinery and drilling equipment.
To ensure that a blast does not cause any damage to the surrounding area, a number of factors must be taken into account; this includes the statics of the object to be blasted and the environment, the calculation of the required explosive charge and the vibrations caused by the blast. “As soon as there is a building in the vicinity, a vibration forecast must be made,” explains Kandlhofer. Reisch remembers that “one or the other chimney” was not properly blown up. Overall, however, blasting is “at least 99 percent safe”.
Planning takes three to four months
Before detonation, holes for the explosive charges of 30 to 127 millimeters are drilled in rock and reinforced concrete. According to Reisch, the explosives vary from gelatinous rock explosives to emulsion explosives such as ammonium nitrate and nitropenta. Planning an order usually takes three to four months.
According to Reisch, clients are “all dismantling companies in Germany” and often the state, for example when bridges like the Salzbach Viaduct have to be dismantled. “Blasting will become more important,” says Reisch, referring to the many dilapidated bridges and buildings in Germany, because “a normal dismantling process takes much longer than a blasting process”.
Other important advantages are that, compared to manual removal, the amount of dust and construction noise are significantly lower, and often the costs too. According to Reisch, the manual removal of the AfE tower in Frankfurt would have cost more than 4 million euros and caused a lot of noise for months. The cost of the demolition, including the safety measures, would have amounted to “less than a million”. The time savings make blasting methods particularly attractive for the dismantling of bridges that are so important for traffic.
Maximilian Barthel, Landgraf-Ludwigs-Gymnasium, Gießen