BOMB SHELTERS:  Germany Third Reich. 1934-1945.  Initial efforts to develop population protection measures in the Third Reich were sporadic and ineffective.  Air raid sirens had been installed in Berlin in 1934, and air raid protection plans drafted in 1935, but shelter construction was very limited - not until August 1939 was new building construction required to include shelters.  With the start of hostilities in September 1939, some trenches were dug in public parks.  During this period much of the shelter construction activity was essentially the result of private enterprise.  Architect Leo Winkel developed the ant-hill design of Luftschutzturme, starting in 1934, and engineer Paul Zombek developed other designs, with the first models completed in 1939.  These air raid towers proved to be effective in sheltering more people in less space than other designs, and the ant hill model offered superior resistance to bomb hits.  Other designs of air raid protection tunnels and simple ground level and underground shelters were developed during this time period.

In 1940 Reichs Chancellor Adolf Hitler authorized an emergency construction program to provide fortified bunkers to shelter 5 percent of the population in 70 selected cities.  By July 1941 specific standards had been established for the new shelters, including:

The shelter program was assigned to the air raid protection department of the Air Ministry, under the supervision of Luftwaffe General Linder.  Many of the same issues that drove British shelter development policies were also considered by the Germans.  Linder is reported to have personally been an advocate of improved cellar shelters, believing that the large bunker shelters undermined morale and diverted materials needed for other programs.

Early in the construction program, bunkers constructed in city residential areas were often designed to blend to as great a degree as possible with the surrounding buildings.  Tiles were used on the bombproof slab roofs; walls were covered by a stone or brick veneer, and in some cases trompe-l'oeil windows and doors were painted on the buildings.  As cities increasingly suffered bomb damage, some shelters were painted to resemble damaged buildings.  

Initial designs were developed based on a 500 pound bomb as the standard threat.  However, increases in the size of the bombs carried by Royal Air Force and United States Army Air Force bomber aircraft drove an increase in 1942 to a 1,000 pound bomb, and later to a 2,000 pound bomb as standard.  These changes drove a steady increase in roof thickness (see Table 1) from 1.4 meters to 2.5 meters over the course of the war. 

Substantial attention was paid to the appropriate construction materials for shelters after an initial survey in 1940 determined that many existing shelters were constructed from concrete that had insufficient cement content.  By March 1944 research efforts had determined that shelters should be constructed using blast furnace cement.  The volumes needed were significant (see Table 1).  In general wall thicknesses were proportionally thinner than the thickness of the roof. 

Bunker foundations were designed as a free floating reinforced concrete slab designed to allow the bunker to shift to absorb the forces generated by a direct hit or near miss.  However, some bunkers were constructed with a deep foundation formed by extending the walls into the ground.  Interiors were Spartan at best, with even fewer comforts than military bunkers and wiring mounted exposed on the walls.  However, more attention was paid to habitability than in the British expedient approaches, with pump operated water and sewage systems, and in some cases electric elevators. 

Table 102-1.  Shelter Construction Parameters From Various Sources

Roof Thickness Concrete Thickness Concrete Volume
Bomb Weight Meters Occupants Meters Occupants Cubic Meters
500 pound 1.4 less than 300 2.0 500 to 600 1,800
1,000 pound 2.0 300-750 2.5 1,000 to 1,200 3,300
2,000 pound 2.5 more than 750 3.0 2,000 to 2,400 5,000
        4,000 to 4,800 8,800

Note:  Specifications for roof thickness (based on bomb weight) and concrete thickness (based on population and logically thickest on the roof) are inconsistent and come from varying dates during the war.  It is not known how this guidance was applied in practice, although the most conservative practice would seem to have been to design for the thickest protection.   

The larger above ground shelters had significant capacities, with populations of 8,000 and in some few cases as many as 18,000.  One of these giant shelters is reported to have sheltered 60,000 persons during an attack on Hamburg.  By the end of World War II the German shelter program could protect approximately 15 percent of the urban population, with a surge capacity through overcrowding to 75 percent.

Sources: Kaufmann, J. E. and H. W. Kaufmann, fortification expert, Fortress Third Reich: German Fortifications and Defense Systems in World War II, Cambridge, Massachusetts, United States of America, Da Capo Press, 2003.

Entry 03102 - posted 8 September 2003