Singapore is a land scarce country with a land area of just 714 square kilometres, accommodating approximately 5.54 million inhabitants as of mid-2015. The city-state is the world’s third most densely populated country after Macau and Monaco, with a population density of 7,697 people per sq km.
Since 1980, Singapore’s land size has expanded by 100 square kilometres, an accomplishment achieved through land reclamations in Marina East, Simpang, Changi East, Sungei Kadut, Pasir Ris and around the Western islands. The population has also increased exponentially from 2.41 million to 5.54 million in just 35 years.
By 2030, Singapore’s population is forecasted to reach between 6.5 and 6.9 million and the non-resident population is estimated to rise from 1.63 million in mid-2015 to approximately 2.3 to 2.5 million, according to the Population White Paper released in 2013.
In a report by Channel News Asia on 29 October 2015, Finance Minister Heng Swee Keat said at the 10th International Conferences on South Asia that land is a valuable resource that must be carefully managed and utilised equitably, taking into consideration Singapore’s small and compact land space.
Hence, maximising land use through innovative solutions is crucial to secure our future living environment. There are two viable options that Singapore can implement to optimise its land space and make room for the projected swelling population: developing outward or downward.
Endless Possibilities Underground
For years, Singapore has been reclaiming land by digging up the ocean and filling it with sand. But land reclamation seems to be a less viable option in the long run: amongst other reasons, Singapore has been mired in some controversy regarding the importation of sand from its neighbours. 
In addition, there are technical restrictions to the height of buildings in Singapore.
When there is limited space and a city gets too crowded on the surface, why not build down?
According to a press statement by Urban Redevelopment Authority (URA), the city planners of Singapore envisage a groundbreaking idea for the city of tomorrow – constructing a city deep underground.
URA’s Group Director for Strategic Planning, Mr Richard Hoo, pointed out that there is potential for a wider use of underground space by tapping on engineering and scientific expertise. URA will also continue to seek innovative urban solutions, which may make underground developments more viable and attractive.
“Singapore is small, and whether we have 6.9 million or not, there is always a need to find new land space,” Professor Zhao Zhiye, the interim director of the Nanyang Centre for Undergound Space at Nanyang Technological University, told The New York Times. “The utilisation of underground space is one option for Singapore.”
By 2050, Singaporeans could be shopping in underground city malls or living in subterranean homes, said the Building Construction Authority (BCA).
In a 2013 blog post by Coordinating Minister for Infrastructure & Minister for Transport Khaw Boon Wan, he wrote that Singapore could utilise more of its underground spaces, citing the examples of Montreal’s Underground City and the extensive underground facilities such as sports/swimming complexes, concert halls and churches in Scandinavia.
By 2050, Singaporeans could be shopping in underground city malls or living in subterranean homes, said the Building Construction Authority (BCA), a local agency surveying the possibilities of underground construction.
Underground Cities Around the World
The underground city is not a contemporary concept. In fact, centuries ago, people had been living below the surface.
The world-famous ancient Derinkuyu underground city in Turkey is a perfect example. In 1963, a man knocked down his basement wall and, to his surprise, uncovered an 18-storey complex underneath, big enough to accommodate 20,000 people. Who built this vast underground labyrinth of passages and chambers with temples, shops, tombs, living quarters and livestock pens 5,000 years ago? It remains a mystery, although there are many theories raised by scholars and archaeologists.
A notable example of a modern subterranean city is Montreal’s Underground City in Canada. Dubbed The Indoor City or La Ville Souterraine, it is an ideal place to escape the winter chill. It is also a shopping paradise for Montrealers. Every day, around a quarter of a million Montrealers as well as tourists descend to the 32 kilometres of tunnels to access banks, hotels, shopping malls, restaurants, exhibition centres, museums, cinemas, nightclubs, library, metro stations and train stations.
Coober Pedy, a town 846 kilometres north of Adelaide, appears to be rather deserted at first glance. But, in reality, around 3,500 people or 80 percent of the residents live below the ground, in homes excavated out of caves. Coober Pedy, famed for opal mining, is of the driest places on Earth with temperatures reaching 40 degrees Celsius in summer. To escape the blazing sun and arid climate, the miners at Coober Pedy started digging into the hillsides, building subterranean ‘dugout’ homes carved from the rock. The dugout is a much cooler place to live in with temperatures ranging from 23 to 25 degrees Celsius, akin to an air-conditioned room.
However, living underground is scary to some people. It is often thought of as dark, eerie and damp. But the dugouts in Coober Pedy have evolved over the years into contemporary underground homes with modern kitchens and televisions. The town hosts many award-winning underground hotels and B&Bs; there are even museums, art galleries, an underground church, a gift shop, a pub and a casino!
Singaporeís Underground Ambition
Following in the footsteps of other world-renowned underground architecture, JTC Corporation is planning a 300,000 sqm Underground Science City (USC) between Science Parks 1 and 2, featuring 40 linked rock caverns that house research laboratories, offices, and data centres at 30 to 80 metres below the surface. The underground biomedical and biochemistry industries could make room for 4,200 working professionals, which include scientists and researchers. The project is “a costly yet much-needed experiment”, as quoted from JTC.
The S$950 million Jurong Rock Caverns (JRC) project is another quintessential underground ambition that took nearly eight challenging years to build, undertaken by Singapore to overcome land constraints.
Deep underground excavation and construction could be extremely expensive to achieve a safe design. In addition, would the construction affect the existing building? And how could we minimise it? Donít forget the Nicoll Highway collapse in 2004.
Dr Lim Yee Yan, civil engineering lecturer at Southern Cross University, Australia, who is also an alumnus of Nanyang Technological University
Another pitfall of going underground is cost. Typically, the development of an underground city is ten times more costly than cities above ground.
The JRC, officially opened on Sept 2, 2014, is an underground rock cavern storage that can hold crude oil and petroleum products of up to 600 Olympic-sized swimming pools, as stated in a report from TODAYonline. Constructed 150 metres below Banyan Basin on Jurong Island, JRC is Southeast Asia’s first commercial underground liquid hydrocarbon storage facility that frees up 60 hectares of surface land, equivalent to 70 football fields.
Eight years ago, the Singapore Armed Forces (SAF) unveiled an Underground Ammunition Facility (UAF), which stores the military’s munitions and explosives. Singapore is also looking into building an underground warehousing and logistic facility.
Other than building expressways, MRT lines, car parks, shopping spaces and storage facilities underground, “[still], there is scope to do much more”, states an online article on the Ministry of National Development’s (MND) blog.
Mr Kwa Chin Soon, a BCA Local Undergraduate Scholar and Senior Engineer, Deep Excavation & Geotechnical Department, told Brightsparks magazine that building underground cities will solve the problem of Singapore’s land constraint, but BCA would have to consider the engineering challenges and, on top of that, it takes time for individuals to be accustomed to subterranean living.
Granted, living underground is not a lifestyle that is easily embraced by all, especially the older generations. Out of superstition, some believe that only the dead would return to the ground. 
Others feel uncomfortable and claustrophobic at the thought of living underground, as subterranean homes deny access to views of the outside world.
“What if there is a fire, flood or earthquake? There would be no way to escape. If there is electricity shortage, I would be stuck in the dark. Living underground is not a good idea; I do not want to live like a mole rat,” said Mr Soh, owner of a small start-up company.
Jingyi, a consultant, is uneasy about this concept too. She said, “I am one who wants to breathe fresh air, thus I prefer living above the ground.”
“You have to consider the psychological effect on people when living underground. A subterranean home is not something I hanker after unless there is lush greenery surrounding it,” echoed civil engineer Mr Do Huu Luan.
Another pitfall of going underground is cost. Typically, the development of an underground city is ten times more costly than cities above ground.  The Netherlands has disbursed S$18.6 billion for the construction of a one million square feet underground city called Amfora, which brings together cinemas, sports halls, shops and car parks beneath Amsterdam’s iconic canals.
In a Lianhe Zaobao article on 14 October 2012, Professor Wang Chien Ming, Director of the Engineering Science Programme at the NUS Faculty of Engineering, was quoted as saying, “When you go underground, you will have to deal with issues such as water leaks and ventilation. As 24-hour ventilation facilities are required, the associated costs will not be low. Underground spaces are most ideal for storage. In this way, there is no need for too many people to gather underground. Furthermore, people also do not enjoy remaining underground for too long.”
Engineers and analysts have also cautioned the authorities against the pitfalls of underground development due to the inconsistent and wide-ranging nature of rock and soil formations in Singapore. 
“There [is a certain level of uncertainty] involved in the excavation and construction of deep underground structures, especially if the depth exceeds our current practice. The uncertainty is magnified by the fact that soil is the most variable and uncontrollable engineering material because it is a natural material. Our (engineering) knowledge on this aspect, despite years of dealing with it, is still considered relatively insufficient in comparison to other man-made materials, such as steel and concrete. Deep underground excavation and construction could be extremely expensive to achieve a safe design,” commented Dr Lim Yee Yan, a civil engineering lecturer at Southern Cross University, Australia, who is also an alumnus of Nanyang Technological University.
He added, “In addition, would the construction affect the existing building? And how could we minimise it? Don’t forget the Nicoll Highway collapse in 2004.”
Regardless of the cost and scrutiny, the possibilities of developing underground are endless and should be carefully considered.
Floating Homes of the Future
If you enjoy relaxing amidst the sea breeze, living on the sea would not be a bad idea. The concept of ‘floating houses’ or water chalets might be refreshing to inhabitants of crowded cities, especially to most HDB dwellers.
From houses on stilts (or ‘kelong’ in Indonesia, Malaysia and Singapore) to the well-known sampan boats — humble accommodations for villagers in Hong Kong’s Aberdeen fishing village — humans have been living on the sea for a long time, even before the idea of floating cities came about.
Floating architectures are popping up around the world, and floating urban expansions are likely to change urban seascapes in the foreseeable future. Norway has Krystall Hotel, a snowflake-shaped floating hotel with 86 luxurious rooms, while a water-based pop-up library debuted two years ago in New York City. There is also a proposed floating hydroponic farm named Arctic Harvester between Greenland and northern Canada.
In the Netherlands, aquatic living is not considered a privilege or even a luxury, but a necessity. Almost two-thirds of its land is vulnerable to being submerged at high tide, and a fifth of its land area is permeated by water. A long history of flooding led to a massive construction of dikes, canals and water-pumping windmills in this low-lying European country.
With rising sea levels and not much land left, the only way out for the Dutch is the floating house.
For instance, Waterbuurt, or “water quarter”, comprises 93 buoyant multilevel houses with balconies, according to the Financial Times. The houses are situated at the IJ Lake in Amsterdam’s Ijburg neighbourhood. They are cosy abodes for an estimated 1,000 residents who swim, fish and sail in the water where they live.
Today, floating architecture is a growing trend in the Netherlands; it is also the ground zero from which thousands of amphibious houses radiate.
To date, the most ambitious floating city plan is the US$167 million (S$225 million) ‘seastead’ project supported by PayPal founder Peter Thiel and the Seasteading Institute. It is looking into international waters to establish a new floating ‘nation’ granted with political autonomy. 
The Upside and Downside of Floating Homes
What is the advantage of amphibious housing? They can insulate our small, low-lying island state from floods, as the modular structures are engineered to float on flooded water and sink to their initial positions when the flood recedes.
Similar to a boat, a house is made floatable when its base density is less than that of water. The base is a buoyant platform or raft built from lightweight materials such as foamed concrete, to establish a large, hollow and airtight ‘concrete tub’. Set on the base is the prefabricated structure of the living space, typically made of wood, glass and aluminium. The house is docked to the lake bed by sturdy steel mooring poles, powered by an electrical grid and plugged in to water and sewage services.
Research by Mr Kelvin Ko, a specialist in floating urbanisation and an intern with Dutch aquatic architecture firm DeltaSync, shows that a 15-storey floating building (of about 50 metres high) can withstand natural disasters, even hurricanes with wind speeds of 200 kilometres per hour.
The findings by Mr Ko, who holds a Master’s degree in civil engineering, have boosted the potential of building floating urban districts in cities such as Hong Kong and Singapore.
About his discovery, Mr Ko added, “Yes, you just have to build the city with several modular floating platforms rigidly connected to each other. This way, the total length and width of the floating city will become larger than the wavelength. This causes the waves to have less effect on the floating city, which will only experience very small displacements, so small that inhabitants won’t feel them. Only under severe wave circumstances (will) the platforms experience large displacements, like during a tsunami.”
Similar to a boat, a house is made floatable when its base density is less than that of water.
Moreover, at greater sea depths, it becomes less costly to build a floating city than to reclaim land.
“We think we should change the mindset of cities. We want to show that water can be part of the city, and it isn’t something to be afraid of,” voiced Mr Koen Olthuis, an architect and founder of Waterstudio.NL, a Dutch aquatic architectural firm, in an interview with Deutsche Welle News.
The downside? You would probably experience a tad of seasickness when the sea gets turbulent, but in time to come, you would get used to it, advised architects.
Floating Urban District in Singapore?
Can you imagine a ‘Floating Urban District’ in the sea around Loyang, Pasir Ris, Sentosa Cove or Marina Bay? It might well be in the minds of Singapore’s city-planners.
Soaring land prices, land scarcity, a burgeoning population, and rising sea levels from global warming and climate change portend the global phenomenon of ‘floating urban homes’; it is a boon to cities, especially Singapore, experts say.
A tropical island surrounded by sea and with its terrain almost as flat as a pancake, Singapore is undoubtedly imperilled by rising sea levels. A finding published by Climate Central noted that by 2100, global warming could result in the submerging of 745,000 local homes due to a rise in Singapore’s median local sea level to 9.5 metres.
With that in mind, building a city in accordance with climate change is imperative for the city-state in years to come as “[it’s] better not to fight nature, but to work with nature, and amphibious architecture is one answer”, said Thai architect Chuta Sinthuphan of Site-Specific Co. Ltd during the first international conference on amphibious architecture. 
Moreover, Singapore’s seas are relatively calm and the building of floating structures is highly suitable. 
If floating houses are to occupy Singapore’s waters in the future, the seacape of the lion city will be even more appealing and fascinating. Individuals who enjoy sea views are also looking forward to living on the sea.
“The concept of floating houses sounds fun! I don’t mind as long as it is safe,” effused Ms Nancy Kong, an administrative assistant.
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 Yang, Calvin. ìSingapore Looks Below for More Room.î The New York Times. 25 Sept 2013. http://goo.gl/gOgvBC
 Misir, Timothy. ìSingapore Looks Underground for Room to Grow.î Citiscope. 28 May 2015. http://goo.gl/RJsrlE
 Chin, Daryl. ìExperts Warn of Hefty Price Tag for Singaporeís Underground Ambitions.î The Straits Times. 10 Sept 2013. http://goo.gl/LrwqG6
 ìFloating City Project.î The Seasteading Institute. http://goo.gl/FqQrMh
 Tang, Alisa. ìThailand Tests Floating Homes in Region Grappling with Floods.î Reuters. 5 Mar 2015. http://goo.gl/rVWw25
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