During the day, the RAW-Gelände is another world from its nights and weekends. The generous laughing and flirtatious winks brought by the clutter of fun looking techno-tourists are replaced by the emotionless stare of working men, refilling the clubs’ stash of spirits, beers and popular carbonated sodas based on this South American tea. It doesn’t keep a group of people from having a good time, climbing up a certain object which stands out at the area. The contemporary usage of this object, nowadays named Der Kegel (The Cone) differs from its history – as the night from the day in its surrounding clubs.
Already since 1867, the area is used to repair trains. Since 1918, it is named Reichsbahnausbesserungswerk (German Imperial Railway Repair Factory) or in short RAW – as is how we still refer to the Gelände (Area) nowadays. A few decades later, this area became witness of a peculiar type of architecture which had nicknames such as Betonzigarre (concrete cigar), Zuckerhut (sugar-loaf) or -by the English- ant hill bunker – referring to the rather crowded content. I am talking about the bunkers who officially were named Winkeltürme (Winkel’s towers), who were named after its designer Leo Winkel – a man of who little is known. Winkel researched the possibility of building aboveground bunkers, fairly new by that time. And for a reason: who could have thought that underground bunkers actually were in need of thicker walls? As a result of digging itself into the ground, the bomb’s explosion creates a shock-wave in the soil. Aboveground, the energy of the blast spreads in all directions. Perhaps of even bigger importance, the Winkeltürme were way cheaper and faster to construct than underground bunkers since it kept from struggling with the groundwater level. The patent for the type of bunker was obtained in 1934, a year before the first Winkelturm -a prototype- was build. When it was tested for being save in January 1936, goats were kept close to its walls inside – testing if too much noise came in. The testing bombs with a weight of 500 and 1000 kilo did not damage the Winkelturm badly. The goats though, ended up more harmed: they were deaf. As a result, some man concluded that a distance of 30 centimeters from the walls would be enough to keep from losing your ability to ever hear the next air raid alarm.
As far as I can see, there were about some 200 Winkeltürme build – in about five different types and many minor varieties. The most important development comes to me as the thickening of walls. In the earliest constructions, these reinforced concrete masses started 1.10 meter thick at the ground level. They slimmed 3 centimeter each meter: so they left only 80 centimeter of concrete protection at ten meters height. The pointy roof –in despite of bombs being unable to spend there last intact seconds on it- was 1.40 thick. In later designs, the protection was thickened up to 2 meters at the ground level as well as its roof – while a thickness of 1.40 meter was required at the height of ten meters. Also, the first designs of the Winkeltürme had two levels underneath the surface and another seven up. The multiple stairs provided in the most efficient way of getting people in the bunker and out again. Up till 1941, the Winkeltürme were build steadily. Then, a lack of resources kicked in. A civil servant calculated that the Winkeltürme were relatively inefficient: a maximum of 3 cubic meter per hider was settled, while the fourth construction demanded 3,50 cubic meter. Some other type even demanded about 6 cubic meter of reinforced concrete for everyone who looked for a shelter. Only a few more Winkeltürme were build in 1942 and 1943.
It is not too easy to find specific information about the bunker at the RAW-Gelände. Given the fact that the walls are about 1.80 meter thick at 10 meter height, this bunker must have been one of the heavier type. Different than most other Winkeltürme, its entrances were at the ground level – while it does not have floors underneath the surface. The most reasonable explanation which come up in my mind goes with the Spree, the river that floats fairly next to it. Therefore, the groundwater level may have been even more of a struggle than usual. The two stairs in the bunker both go up, leaving only small platforms in its middle. Most of the (estimated) 400 people which were able to find shelter in this bunker, must have stand at the stairs. The walls were pierced through by holes in multiple sharp angles: providing the bunker’s population with fresh air while grenade’s splinters were kept outside. At the bunker’s peak, a periscope was able to investigate if the Allies already stopped testing Newton’s law of universal gravitation over the Berlin airspace.
After the War, about 60 percent of the Winkeltürme were deconstructed during the demilitarisation of both Germanies. At the ground for the repair of East German trains, this bunker survived while it proved its safety as a storage for inflammable products. Since a bunch of years – Der Kegel is decorated with yellow, green and black climbing holds. Also, the pointy roofs up the entrances are removed so one can recover after crawling vertically for three meters. Der Kegel‘s inside is kept from the public eye – albeit that the renters are gentle towards the young and local historians! They held the door open for me to go in and allowed me to take photos. As a consequence, I recommend to do climbing sports at Der Kegel: it makes you feel like besieging a structure which couldn’t be destroyed by bombs. The first requirement though is to visit the RAW-Gelände during the day in stead of the night!
Update: a well informed spirit told me that the Kegel is not a Winkelturm, but a Zombeck-Turm, made by a competitor. Paul Zombeck made minimal differences in the constructions of the Winkelturm and got a patent for his type of bunker by 1937.