Despite the massive visible damage on the only surviving arch (twelve were originally planned), the structure permits some insight into the construction techniques used to build it. The original plans called for the bunker to be 400 meters in length from east to west. A single semi circular roof arch was to measure 33 meters in width and was separated from the next arch by a 30 cm gap, which was to be covered as soon as the bunker was completed. The entire width of the bunker arch was 85 meters. From the sole to the ground, a distance of 32.20 meters was recorded of which 13 meters were above and 19.20 below ground level. The thickness of the roof was precisely 3 meters to which another 2 meters of concrete were to be added upon completion for a total thickness of 5 meters. The top layer of the roof was to be covered with earth to promote tree and plant growth which would serve as natural camouflage against enemy aerial reconnaissance. A 5 meter thick wall was planned to cover both entrances which would add safety in case of air attacks and ground fire.
The bunkers conception also introduced new construction techniques. After clearing the forest, the humid soil was transported away to make way for the bunker. First, a five meter deep Entnahmetunnel was constructed. The Entnahmetunnel was a small service tunnel that was dug into the ground under the planned position of an arch. Its purpose was to remove the gravel that would be used to shape the arch. Next, holes were dug for the foundations of the bunker, which had to be extremely resistant. Once the concrete foundations were planted, gravel and earth were shoveled over the closed Entnahmetunnel and foundations to help in the shaping of the arches. As soon as this was completed, the semicircular mound was smoothed and flattened and then covered with a 10 cm thick layer of concrete. Long metal rods were then inserted into the think concrete layer to act as the starting point for the three meter thick bunker roof. Most of the cement was created at the nearby cement mixing sites. Pumps pumping liquid cement were also employed in the building process.
The picture on page twenty-five shows the construction condition at war’s end, viewed from east to west. In the foreground along the construction site, train tracks are visible next to the cement air vents as well as an entrance and exit. A wall made of light cement dominated the middle section. Also visible in the background are the three-meter thick doors from arch seven. Heavy-duty cranes are also visible.
After the concrete of the first arch fully dried (which took almost twenty days) the builders then removed the semi-circular gravel and earth below the arch, which had been allowed to stay in order to shape the arch’s roof. It was exactly for this purpose that the Entnahmetunnel was built.
The tunnel functioned as follows.
A small lorry on rail tracks entered from the east side. Once parked in the proper position, the silo doors of the tunnel would open allowing gravel and earth to fall through and filling up the lorries. Once finished, the gravel was used to aid in the construction of other arches. Upon the completion of the single arch, the tunnel was removed. The same process would be applied to all the other completed arches.
It was originally planned that the bunker would have eight internal levels. Plans were also drawn up to add stairs, elevators and more pillars for added structural support, all made from finished products that had been put together in workshops in Ampfing and Mittergars. However, these plans were never realized due to the war situation. At the end of April 1945, only arches one to seven of the original twelve planned had been completed. Disruptions in the supply of materials, air raids and lack of skilled workers delayed the project. The bunker itself was never bombed by the Allies.
← last page overview next page →