Subterranean ideas resurface

Posted On Wednesday, 22 January 2003 02:00 Published by
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Economic factors have brought underground living back into vogue, says Ross Davies.

Fiona Chow 2

To some, it is one ofthe great challenges that lie ahead. To others, it is more a case of back to the future - though perhaps ''down'' describes better the growing commercial interest in building underground.
In Renaissance Italy, Leonardo da Vinci toyed with the idea of a ''city under the city''. In 18th-century England, dairy cows were kept and milked in central London?s extensive network of tunnels; and Victorian and Edwardian developers incorporated cellars and sub-basements into offices, warehouses, factories and public buildings as well as into homes.
We have long been familiar with underground road and rail links but for many years now the high cost of excavation in towns - up to £80m a mile for such tunnels in the UK - has driven commercial developers to build upwards rather than downwards. Yet what, figuratively speaking, might be called a subterranean shift is now taking place.
Fears of a replay of September 11 2001 in cities other than New York have something to do with the renewed interest in the underground.

So, too, does the remorseless spread of cities. Tokyo?s population already exceeds 26m, China is building 40 new cities and, by 2006, one in two of the world?s population is likely to be a city- dweller. In more mature cities, planning constraints and the desire for more light and open spaces limit expansion upwards or outwards.
At the same time, the costs and risks of building underground are falling, absolutely as well as relatively. According to a study by the Automobile Association, new technologies are reducing tunnel construction costs year by year, though some savings are counterbalanced by the increasing costs of safety and environmental legislation.
''Advances in numerical analysis allow the improved prediction of ground movements, stress changes and groundwater flows caused by underground construction and tunnelling,'' says Fiona Chow, associate director of Geotechnical Consulting Group. Ms Chow, who advises on the Crossrail link between Heathrow, Stratford and Canary Wharf, points to Big Ben and cites the Houses of Parliament as an example of a ''sensitive'' structure undamaged by tunnelling for the Jubilee Line extension of the London Underground.
The new British Library in London has a 23-metre-deep basement that houses more than 11m books, while the British Museum now has an underground lecture theatre beneath the Reading Room. In Paris, a new entrance hall and galleries are buried in the courtyard of the Louvre, an innovation that offered the designers greater freedom with the layout of the galleries, as well as keeping the ground surface uncluttered.
Engineers are making progress in alerting developers, governments and planning authorities to the commercial and industrial as well as the aesthetic possibilities of building underground, a cause that Ms Chow champions in Ingenia, the journal of the Royal Academy of

Examples of this business appeal are surfacing in many countries. Montreal comes as close as anywhere in realising the ''city beneath the city'' of Leonardo?s dream. Below Montreal?s streets are offices, 1,600 shops, 200 restaurants, 40 banks and 30 cinemas as well as hotels and rail, metro and bus stations.
Escape from the savage Canadian winter climate is the driving force behind Montreal?s move underground, yet in Europe there are many examples of more positive reasons for digging in.
One of the largest underground spaces in the world is Helsinki?s Viikinmaki waste-water treatment plant, which processes all of the Finnish capital?s needs. Going underground eased the initial planning permissions and now reduces gas emissions and noise pollution. Future expansion will involve less disruption to the houses and parkland above.
The ground itself has much to offer. New technologies, for example, are unlocking the possibilities of thermal energy storage. In the Netherlands there are about 200 storage projects for cooling or heating and in Sweden another 100 or so.

Thermal energy storage makes it possible to iron out peaks and troughs in production and distribution. It can also lower costs and environmental damage by bringing down the size of distribution units.

One British example is Oxford university?s Keble College. The ground temperature beneath Keble remains at about 13° Celsius all year and the college is able to store this ''heat''. A heat-exchanger and system of pipes circulating salt water through the building?s piles, floors and walls help to keep Keble warm in the winter and to run air-conditioning in the summer.
Apostles of the underground have one powerful weapon working in their favour, which is that they can stop men digging up the roads all the time. Dr Chow says: ''Helsinki has built a single set of deep, multi- purpose tunnels beneath the city to house electricity, water, heating and communication cables, as well as a roadway for vehicular access, inspection and repair.''

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