How an Underground City Keeps Singapore Running

Beneath Singapore's Streets Lies Another City You Rarely See

When you think of Singapore, you probably picture gleaming skyscrapers, lush gardens, Marina Bay, and one of the cleanest and most modern cityscapes in Asia.

But some of Singapore's most impressive engineering isn't above ground.

It's beneath your feet.

Under the streets, buildings and parks lies a growing network of train tunnels, pedestrian walkways, utility corridors, water infrastructure and enormous underground caverns.

For a small island where every piece of land matters, going underground isn't simply an engineering achievement.

It's part of how Singapore creates more room for the future.

When You Can't Expand Outward, Look Down

Singapore has always faced a geographical challenge: **limited land**.

Homes, offices, factories, roads, parks, reservoirs and transportation systems all have to compete for space on an island of limited size.

Singapore has responded in several ways.

It builds upward.

It has reclaimed land from the sea.

And increasingly, it is looking downward.

By moving infrastructure and facilities underground, valuable surface land can instead be used for homes, parks and community spaces.

Singapore's Urban Redevelopment Authority (URA) now plans underground space as an important part of the country's long-term development strategy.

The MRT Is Only the Beginning

For most visitors, the first underground Singapore they experience is the MRT.

Step into stations beneath areas such as Orchard Road, Marina Bay or the city centre and you'll discover that the underground world is much larger than a railway platform.

Stations connect to shopping centres, office towers, hotels and pedestrian passages.

In some areas, people can walk considerable distances without returning to street level.

But trains and shopping malls occupy only the relatively shallow layers of Singapore's underground world.

Go deeper, and things become much more interesting.

Hidden Tunnels Carry the City's Essentials

Beneath Singapore are networks carrying things most people rarely think about:

Electricity, water, telecommunications, sewage and other essential services.

Instead of allowing every utility to compete independently for underground space, Singapore has increasingly developed shared infrastructure such as **Common Services Tunnels**, where multiple utility systems can be organised within the same underground network.

This doesn't make for spectacular tourist photographs.

But without these hidden systems, the modern city above couldn't function.

A Sewer System Deep Beneath the City

One of Singapore's largest underground engineering projects is something tourists will probably never see:

the **Deep Tunnel Sewerage System**, or DTSS.

Rather than relying entirely on numerous pumping stations and conventional sewer networks, deep tunnels carry used water across Singapore toward major water reclamation facilities.

It's essentially a massive underground highway—

except instead of cars, it carries wastewater.

The system allows Singapore to manage water infrastructure while reducing the amount of valuable surface land required for these facilities.

In a country where land and water are both precious resources, putting such infrastructure underground solves more than one problem at the same time.

Singapore Even Stores Oil Underground

Perhaps one of the most surprising places beneath Singapore is the **Jurong Rock Caverns**.

Located about **150 metres underground**, these enormous caverns were carved into solid rock beneath Jurong Island.

Their purpose? To store liquid hydrocarbons.

The facility can hold approximately **1.47 million cubic metres**, and placing this storage underground saves around **60 hectares of surface land**.

That is land that can instead be used for higher-value industrial activities.

It was also the first commercial underground rock cavern facility of its kind in Southeast Asia.

Imagine standing on Jurong Island without realizing that, far below you, an enormous industrial storage complex is hidden inside the rock.

Not Everything Underground Is for Machines

Singapore's underground strategy isn't only about infrastructure.

The spaces closest to the surface can serve people too.

Underground pedestrian networks can connect MRT stations with offices, shopping centres and other buildings, allowing people to move through busy districts away from traffic and tropical heat.

Car parks, retail spaces and public facilities can also occupy these shallower underground levels.

Singapore's planners generally envision different depths serving different purposes:

**Near the surface:** people, shops and pedestrian connections.

**Deeper underground:** trains, utilities and infrastructure.

**Deep inside rock:** large caverns for storage and other suitable uses.

In other words, the underground can be planned almost like another layer of the city.

Planning a City You Can't See

Building underground comes with an unusual problem.

You can't simply look around and see what's already there.

There may be railway tunnels, building foundations, utility lines, geological formations and other infrastructure occupying the same invisible space.

That's why Singapore has increasingly used **3D mapping and underground planning** to understand what lies beneath the city.

Government agencies coordinate infrastructure plans years in advance so future tunnels and utilities don't unnecessarily compete for the same space.

Singapore isn't simply digging holes whenever it needs more room.

It's increasingly planning underground space as carefully as the city above.

Could Singapore Go Even Deeper?

Probably.

Singapore's Master Plan 2025 continues to explore new possibilities for underground development.

Future underground spaces could potentially accommodate more storage, infrastructure, utilities and industrial functions. Planners are also studying additional cavern possibilities, including underground storage for construction materials.

The idea isn't to move Singaporeans underground.

It's almost the opposite.

By placing more of the infrastructure that people don't need to see below ground, Singapore can preserve more valuable surface space for the things people do want:

homes, parks, nature, businesses,

and places to live.

The City Beneath the City

Millions of people move through Singapore every day without thinking about what lies underneath them.

Trains rush through tunnels.

Water travels through enormous underground systems.

Electricity and communications pass through hidden corridors.

Oil is stored inside caverns carved deep into rock.

And above it all, everyday life continues.

Singapore is famous for making the most of limited space.

For decades, that meant building taller and reclaiming land from the sea.

But the next chapter of Singapore's urban story may increasingly be written somewhere most visitors never think to look.

**Down.**