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Application areas for multiple (underground) land-use

In contrast to hi-rise building, underground building is expanding the third dimension down underground. This reversed direction is responsible for some important disadvantages concerning construction costs, daylight entry and the spatial identity of the (underground) building within its surroundings. Application of underground space will be successful when these limitations are met with at least equal benefits. In this respect it is necessary to define a series of strategic application areas for the use of underground space. Three examples are discussed below.

Limited underground incisions resulting in large aboveground consequences
Land-uses and urban facilities like infrastructure (highways, motor ways and railways), heavy industry, gas stations (storage of LPG) and sewage treatment plants make up a promising group of potential underground applications. Once situated underground, there is not only the benefit of direct multiple land-use straight above the facility. Also a much wider additional area will be relieved from the negative environmental impact they are normal cause aboveground. Equally, underground spaces make it much easier to contain noise and emissions and to turn the external risks into much smaller internal ones. In this way underground space can cause significant multiplier effects as far as multiple land-use is concerned.

Rising the stake: underground stations
Increasing urban densities through multiple land-use should relate directly to policies managing traffic problems. For the region as a whole an increase of urban density can shorten daily trips and stimulate the use of public transport. At the spot where the additional floor area is realised, however, increasing densities will result in more urban activities and thus in more traffic movements, while at the same time the available space to deal with this increasing traffic will diminish. In most post-war residential areas this won't be a problem, as here the amount of traffic space is most of the time overdimensioned. In the more compact urban areas like city centres and their fringes, it will become necessary to deal more economically with traffic space. Although underground can help here in general, it will be preferably to impose infrastructure that deals efficiently with the space and energy it requires: cable for electronic information, tube transport for goods and mass transit for people. Among these three modes of transport, mass transit has a special dimension for multiple land-use. Again, it is not only the space straight above the facility that becomes suitable for additional land-uses. In contrast to the previously mentioned `negative' urban functions, this time there is no removal of a negative influence but a positive one is put into place: environmentally friendly and space-efficient mobility.

Extra attention should be paid to the additional (underground) integration of the railway or subway station in the surrounding urban structure, including these areas where extensions of transit networks are being planned but not yet underway. To the benefit of the transit system it is necessary to bring as many potential travellers as possible into the reach of its stations by increasing building density and functional intensity. At the same time these extra people have to experience enough spatial quality and safety in the station (area) so they are willing to use the underground facilities. The main problem faced here is the transfer of the transit users from the deeper lying urban layers to the city's surface in a safe, comfortable and human way. Recent examples of underground stations show a functional intermingling with shops and services, strategically dosed daylight and clarity of architectural design to tackle this problem.

The difference between
`a part of all buildings underground' and `all buildings partly underground'
Evoking a mental picture of high urban densities through the use of underground space might be somewhat puzzling. One can easily be tempted to focus on complete underground solutions for each separate urban function, overlooking that partly underground solutions can be just as effective. In general, buildings contain a mixture of several functions. Most of the time, a few them are insensitive to absence of daylight, an entrance from above or other underground design aspects. In these cases it is possible to make a well-considered division within the building between aboveground multiple land-use and underground multiple land-use, resulting in a construction that is much easier to fit into its surroundings. Functions like shopping, storage, services, delivery, production and carpark can be considered to position underground while shopping, offices and housing remain aboveground.