In underground air-raid shelters there are located many functions for civilian use, for instance storage and sports. In Turku, Finland, an underground shelter is being built in which two ice-hockey rinks will be situated in adjacent halls. The unusually long spans of the halls (32 m) presume thorough site investigations and accurate calculations. The construction site is composed of firm crystalline rock. Excavation and strengthening work will take place in many different stages.
According to Finnish legislation new buildings of a volume of at least 3000 m3 shall be provided with air-raid shelters. The air-raid shelter can be built either in the basement of each building or, alternatively, regional shelters can be built with spaces provided for several buildings, blocks or a whole district. As the Finnish bedrock generally is of good quality~ in almost every place there is rock available, the large regional shelters are almost always built in rock. In the rock shelters the space reserved for one person is 1.1...1.2 m2. Usually the rock shelters have plenty of hall space which can be used for civil purposes. The designing and constructing of rock shelters should always be programmed so that the intended civilian use is known already at the initial stage of the designing process, thus making it possible to design the spaces, technical equipment, passages and entrance structures above ground purposefully. from the point of view of the use as well in crisis as in normal times. When the constructing of the rock shelters started in the early sixties in Finland, the shelters were designed to be used in normal times as simple storage rooms or car parks. When the first shelters were completed it was discovered and generally accepted that the shelters could, with small additional expenses, be equipped for more exacting use and activities. In the rock shelters of today the civilian use is more versatile than earlier. Halls for gymnastics and playing ball, running tracks for athletics, places for jumping and throwing have been built in the shelters and in two towns there are public swimming pools in the rock shelters. In addition to that, provided in the rock shelters. bowling alleys will be built. rinks will be built. hobby rooms for young people and rooms for musical training are In the shelters being designed 'at 'present, cinemas, small, theatres, In the rock shelter of the Varissuo -residential area in -Turku two ice
The building of the Varissuo residential area in Turku was started in 1978 and by now about 60% of the dwelling houses have been built. The total area of the dwelling houses is about 320,000 m2, excluding schools, nursery schools, business buildings etc. The topography of the area varies and there are large exposures of rock. It is possible to build the regional rock shelter for the whole residential area, as the area is being built centralized and rapidly by one and the same builder, the population of the area is sufficient and the bedrock is suitable for the purpose.
