A city under the sea?

Claire Huang Today Online 18 Feb 10;

SINGAPORE - The Singapore public has been prepped for the notion of underground cities - but what about underwater ones?

Following the Economic Strategies Committee's recommendation that the Republic explore the use of more subterranean space, observers are expecting the government to introduce related changes to land zoning policies and measures in the upcoming Budget.

"At the moment we're only using the top shallow depths. In fact we can go deeper, as much as 100m, depending on the geological formation," said Associate Professor Chu Jian of the Nanyang Technological University's School of Civil and Environmental Engineering.

And his research shows the feasibility of underwater cities. "In fact, the idea is not new. An underwater city in Bulgaria has been created," he said.

"And underground cities are not expensive, if done on a large scale - the same as for land reclamation in the past."

Strong seawalls could be built to block the water, creating space behind - for shopping centres, factories or storage space.

"If you have larger-scale constructions and more international firms are willing to bring in more advanced machines and technologies because it's more cost effective, this will further reduce construction costs," said Assoc Prof Chu.

Currently, Singapore has three such underground networks: At Raffles Place, at CityLink Mall and linkways at Orchard Road. The government is also in the process of implementing the Jurong Rock Cavern for oil and gas storage at Jurong Island.

But such measures can get tricky, given the considerations of buildings above ground and geological formations. "For example, if you want to do deep excavation below (Raffles City), it may not be feasible."

The committee had also recommended transforming the existing Keppel and Pulau Brani area, once its lease expires in 2027, into a Tanjong Pagar Waterfront city.

Because of years of container work there, the ground - which was used for heavy-duty work - can be converted into foundations for high-rise buildings, said Assoc Prof Chu.

Limited land area means more underground and underwater cities: experts
Claire Huang, 938LIVE Channel NewsAsia 17 Feb 10;

SINGAPORE: Experts said they won't be surprised if the government introduces changes to land zoning policies as well as measures in the upcoming Budget that will enable the use of subterranean space.

Earlier this month, the Economic Strategies Committee recommended that Singapore explore the option of building underground cities.

With a rapidly growing population, Singapore's 700 square kilometre land area isn't enough.

So experts said digging down, like the underground networks in Japan and Canada is the way to go.

Associate Professor Chu Jian, School of Civil & Environmental Engineering, Nanyang Technological University, said: "At the moment, we're only using the top shallow depths. In fact we can go deeper. How much deeper? Well, it'll depends on the geological formation. Sometimes it can be just a few metres, sometimes it can be up to 100 metres."

In fact, Singaporeans can even look forward to underwater cities if Dr Chu's research pans out.

Associate Professor Chu Jian added: "Approach number one is we use concrete structures to build underwater infrastructures like underwater shopping centres, underwater factories or underwater storage space and at the same time, we create land on top, without using much materials. This method is recommended for reclamation in deep water.

"Using concrete structures to build very strong seawalls, to block the water and then to create space behind. In fact, this idea is not new. An underwater city in Bulgaria has been created."

And underground cities are not expensive, if done on a large scale.

Associate Professor Chu Jian explained: "If we go to a larger extent to develop underground space, then the overall cost will be cheaper. Same goes for land reclamation in the past. So if you have a larger scale constructions and more international construction firms are willing to bring in more advanced machines and technologies because it's more cost effective, then it will further reduce construction costs."

Currently, Singapore has three such underground networks at Raffles Place, CityLink Mall and linkways at Orchard Road.

The government is also in the process of implementing the Jurong Rock Cavern for oil and gas storage at Jurong Island.

But such measures can get tricky.

Associate Professor Chu Jian added: "For shallow construction, it's actually controlled by the buildings above the ground. For example, you already have Raffles City above the ground.

“If you want to do deep excavation below, it may not be feasible. For deep excavations, in terms of creation of caverns, it is controlled by geological formation. So you will need good quality rocks for you to do that."

The Economic Strategies Committee also released recommendations to transform the existing Keppel and Pulau Brani area into the Tanjong Pagar Waterfront city, once its lease expires in 2027.

And experts said because of years of container work there, the foundation is strong for such a change to take place. - 938LIVE/vm