The Urban Redevelopment Authority (URA) plans to develop a set of guidelines on subterranean development here, in a step towards creating an underground master plan.
It has called a tender seeking consultants to "develop a comprehensive and holistic framework to enable more extensive use of underground space in Singapore".
The URA said this will help steer future decisions on land use and safeguard areas for potential underground developments.
It said the recommendations and guidelines will also guide the preparation of an underground master plan to "dovetail" with the current land use master plan.
The latter sets out how much needs to be built to efficiently spread the population across the island.
In September, National Development Minister Khaw Boon Wan wrote in his blog that there is scope to do much more in terms of using underground spaces here.
He mooted the possibility of an underground equivalent to the master plan to complement developments above ground.
Before developing guidelines for the URA, the consultants will have to research case studies and the best practices of underground developments around the world.
They will also review all the past studies on the subject done in Singapore and benchmark the Republic's use of subterranean spaces against other cities.
Mr Khaw had cited underground city Reso in Montreal, which is used by 500,000 people daily and boasts offices, hotels, cinemas and even universities.
In Scandinavia, swimming complexes, concert halls and churches have also been built below the surface.
The study should also look at the extent to which basement structures are currently used for carparks and malls and how much key infrastructure such as the MRT is housed beneath the earth.
Using examples from overseas, consultants should provide recommendations and set guidelines on using underground spaces.
These should include:
- How to identify locations to build underground;
- Integrating developments above and below ground; and
- Legislation mandating developers to go underground.
The URA also highlighted several challenges in implementing underground projects here, such as high costs and a lack of proven uses of deep cavern space.
In terms of underground pedestrian links, there is a lack of incentive to build these connections and building owners are reluctant to do so, it noted.
Experts here have also cited the varied nature of Singapore's rock and soil formations as another challenge.
Existing subterranean developments here include the Jurong Rock Caverns, which store petrochemicals and oil.
There are also plans for an underground science city beneath Kent Ridge Park.
Mr Lim Peng Hong, who owns engineering firm PH Consulting, said studies on underground use have been done before.
However, this latest one mooted by the URA is more comprehensive.
The higher cost of going underground must be weighed against the benefits, he said.
He added that the psychological impact of working or doing activities underground must also be considered.
"That's probably why the URA wants to look at best practices, at how other countries are using the space and how they make it more acceptable to people."
