The other one is concealed in the wall and rolls out on tracks which are concealed, normally, by cast-iron plates along the floor. (See fig. G-13.) FIGURE G-13.-VIEW OF ENTRANCE TO Moscow SUBWAY STATION INDICATING CONCEALED BLAST DOOR IN WALL The present Moscow subway, which is about 43 to 45 miles long, could shelter from 1 to 2 million persons in the lower stations and tunnels. The Soviet manual indicates it may be feasible to use the tunnels for shelter purposes. This would represent about 20 to 40 percent of the city's population. During the present 7-year plan it is to be expanded by about 35 miles. SOVIET BASEMENT SHELTERS The Soviet basement shelter is a special structure built inside the basement of an apartment house or public building and designed to protect people against some blast as well as against radiation, fire, collapsed buildings and debris, chemical and bacteriological agents. This shelter is completely below ground level. Its roof is made of various thicknesses of reinforced concrete supported by steel or reinforced concrete beams capable of withstanding at least the collapse of the building above. Depending on the type of building used, such shelters may occupy part or the entire width of the basement, but where possible, it will be built without using the basement walls in order to increase the shielding effect. This is the ideal part, so that you have the space and the added shielding from the outside wall. If this cannot be managed, you will use one wall. If the building is too narrow, they will use both. Inside it is divided into compartments for added strength and to protect people against partial blast damage. Depending on design and materials used, the basement shelter can withstand blast in the range of 10 to 100 pounds per square inch. The recommended capacity of such shelters is 100-150, but it may be larger. EQUIPMENT FOR BASEMENT SHELTERS The basement shelters are equipped with double airtight steel doors edged with rubber, toilets, water, heating, light, storage batteries, double bunks and possibly bottled oxygen. (See fig. G-14, p. 284.) The standard filter ventilation unit, which has been in production for a number of years, is hand or electrically operated, and capable of filtering out radioactive dust as well as chemical and bacteriological agents. It has three large chemical filter cannisters. These are quite elaborate, incidentally, and will take out most of the agents previously listed. This is a fairly expensive unit and some of the pipes are made of high-grade steel. Its air output is sufficient for about 150 persons, providing them with 1.17 cubic feet of air per minute per person. (See fig. G-15, p. 285.) |