This review of tendencies in urban development and in the demand for underground construction is intended to point out the possible urban future for an expanded utilization of subsurface space. The tendencies for urban concentration and for structural complexity of functions within local areas are remarkable. The demand for setting free the land surface from disturbing and disabreable activities in order to attain tolerable living conditions will be a strong motivation for subsurface utilization. The experience of recent subsurface constructions will be of priceless value for future urban development.
The agency for social and economic affairs at the UN estimates, based on good premises, a growth of the world's population between 1980 and the year 2000 amounting to 2 milliards. The population today 4.3 milliards will increase to some 6 milliards. Fig. 1. The population within urban conglomerations will grow by 1 milliard to 2.5 milliards through the same period. The total population of the world will double within 40 years and the population of urban conglomerations will triple during the same interval. We can therefore foresee a gigantic urban development in various parts of the world. In the next twenty years the most comprehensive urbanization will take place in less developed regions, where the additional population will be twice the contemporary. The addition of urban population in more developed regions will number 33 %. Cities have been and should for the future be the best man has ever created. The city is the physical background for large groups of individuals. It is the bearer of historic tradition, of culture and art. It is the venue for important solemn and everyday activities. In various ways the inhabitants of the city and its vicinity have a strong relationship with the city. Over a period of 100 years the old traditional cities have been influenced by powerful forces, which have caused great changes. These are the population growth, the motordom, other technical development, changes in commercial and industrial life and changes in way of life. The changes have caused other utilizations of land and buildings, reconstructions, demolitions and spreading out of building. The changes have to a large extent aimed at satisfying quantitative demands and sectorial demands for technology and economy. Too little attention has been devoted to the build environment and the demand of the inhabitants and their requirements for reasonable quality of life. In many metropolitan areas people suffer from unsatisfactory human, social and physical environment, from lack of meaningful employment, of advanced criminality and time-consuming daily long distance travelling. The costs for construction, operation and maintenance of metropolitan cities reach the limit for the solvency of the population.
Highly qualified experts have tried to foresee and to describe the changes that will affect European cities up to and through the turn of the century. Several tendencies of the present times seem to constitute the basis for predictions on highly changed conditions and on new valuations in urban development and in urban living.