In September,Singapore began to consider a novel solution for its problem of a lack of space to grow extending the city-state underground. A look at how this will be done and at other underground cities: Cut-and-cover method * Structure is built inside an excavation * Used when tunnel profile is shallow * Used for underpasses,approach section for mines * Two types of construction employed for this Bottom-up * A conventional method * Waterproofing can be applied to outside surface * Inside of the excavation is easily accessible for construction equipment * Drainage can be installed outside Top-down * Allows early restoration of ground surface above tunnel * Temporary support of excavation walls used as permanent walls * Shorter construction duration by overlapping activities SINGAPORE Current population: 5.4 million Projected population in 2028: *6.9 million people *Rising sea levels a worrying factor *12 km of expressways and 80 km of transit lines already below ground Jurong Rock Caverns,a huge underground oil bunker * Located underneath the Banyan Basin,off Jurong Island on the western coast of Singapore * Southeast Asias first underground liquid hydrocarbon storage facility * Cost: US$761 million * When completed,will free 150 acres,equivalent to six petrochemical plants * Two access shafts almost completed * Will be ready by 2014 * Cavern itself will be up to 27 m high * Will create 1.47 million cu metres of storage space * Tankers and ship to dock overhead to allow oil to be conducted underground Underground Science City * 40 interconnected caverns for data centres and R&D laboratories which would support the biomedical and life sciences industries * Estimated size is 50 acres * Will be 30 stories below a science park * Will house around 4,500 scientists and researchers Malls on Orchard Road (Singapores shopping hub) * Ngee Ann City retail complex spans 7 levels,of which one is underground * Is accessible by using underground walkways from Orchard metro station Projected problems *Subterranean projects can be three to four times as costly as surface projects *Will need extensive soil investigations *Tricky task of weaving underground and overground utilities cables,pipes,drainage reservoirs *Could lead to psychological issues *Superstitions (only dead return to the ground) Would require proper ventilation (costly) *As previously untouched soil is broken into,carbon dioxide would be released OLD UNDERGROUND CITIES Beijing,China * A network of tunnels built under the city as a bomb shelter * Has schools,restaurants,factories,theatres and a roller skating rink Cappadocia region in Turkey * Has around 200 cities under-ground * Believed to have been built to protect in case of an invasion Portland,US * Has a series of Shanghai Tunnels * Used to move goods,later used for smuggling,Shanghaiing (abducting of people) Coober Pedy,Australia * Underground city that is still home to tens of thousands * Built to escape the heat above,is also called the worlds opal capital for its opal Compiled by Aleesha Matharu and Joyeeta Biswas; Graphic by Pradeep yadav
