What are city digital twins, and how are they shaping the future of our urban centres?

Digital twin cities are already changing the way cities are imagined and managed. But what are they exactly, and how are they built?

Today’s cities face complex problems. They need to move people efficiently, use energy more wisely, respond faster to disasters, and plan for a future shaped by climate and population change.

But researchers Milad Haghani,  from the University of Melbourne’s School of Electrical, Mechanical and Infrastructure Engineering and Abbas Rajabifard and Benny Chen from the Centre for  Spatial Data Infrastructures and Land Administration say solving these challenges doesn’t only mean more infrastructure.

“It also requires seeing the city in motion, before problems arise, or responding in real time.

“This is where city digital twins come in. They’re one of the most talked-about technologies in urban planning and infrastructure. But despite the buzz, many still aren’t quite sure what they are, or what they can actually do.”

The idea itself isn’t new. In fact, its roots go back to one of the most high-stakes problem-solving environments in history: the NASA space program, Associate Professor Haghani says.

“During NASA’s Apollo mission in the 1960s, engineers couldn’t fix problems on board the spacecraft directly. So, they created exact replicas here on Earth – models that mirrored the spacecraft’s systems in real time. When disaster struck Apollo 13, it was this replica – a kind of early twin—that helped mission control troubleshoot, simulate options, and bring the crew home safely.”

Fast forward half a century and NASA, along with others in the aerospace community, still continues to develop and utilise high-fidelity digital models of physical systems.

“Today, the same principle is being used in our urban systems and on a far bigger scale. Cities around the world are now building their own digital counterparts: real-time, data-driven models that can test ideas, spot risks, and improve how urban systems operate – from transport to energy, from construction to emergency response.”

What is a digital twin, and how are they made?

Professor Rajabiford explains that a digital twin is a virtual model of a physical place, system or asset, updated continuously with real-world data.

“Unlike a traditional 3D model or map, or a physical replica, a digital twin is dynamic. It reflects what’s happening on the ground in real time. And more importantly, it allows planners, engineers, and emergency responders to test different scenarios virtually, before taking action in the real world.”

To build one, you need a few key ingredients.

“First is data: from sensors in roads, energy systems, public transport, and buildings. This might include traffic volumes, electricity usage, temperature, wind speeds, or pedestrian movement.

"Next is mapping and modelling technology, like GIS (geographic information systems), BIM (building information modelling), and satellite imagery. These features help create the spatial structure of the twin.

“Then comes the engine: cloud computing, machine learning, and real-time analytics that process and update the model constantly. Together, these are meant to create a living, evolving digital replica of the city. One that doesn’t just show what is, it helps ask what if?”

What can cities do with digital twins?

Cities are complex systems. Roads, trains, buildings, drains, power lines, parks and people – all operating together, all constantly changing. Digital twins give planners and governments a tool to understand that complexity in motion.

They allow cities to test policy choices and infrastructure plans before committing to them.

Want to close a major road? Add a new train line? Change land-use rules in a flood-prone suburb?

"A digital twin can simulate the ripple effects of those decisions—on traffic, emissions, travel times, or stormwater flow", Dr Chen explains.

“They can also help respond to emergencies faster and more precisely. If a bushfire threatens the city fringe or floodwaters rise in a low-lying area, a digital twin can quickly show which roads are likely to be cut off, where evacuation routes are needed, and how fast conditions might change.

“In day-to-day operations, digital twins support smarter maintenance and energy management. They can help detect when infrastructure is under strain, where heat islands are forming, or which buildings are using more energy than they should.”

Real world examples

Digital twins aren’t just ideas on paper. They’re already being used in cities around the world—sometimes behind the scenes, but with growing impact.

In Singapore, the government has developed Virtual Singapore—a high-resolution, real-time digital twin of the city.

The government launched the Virtual Singapore project in 2014, building on earlier efforts to develop 3D urban modelling capabilities. It became one of the world’s first national-scale digital twins.

“Virtual Singapore is used to simulate everything from pedestrian movement to energy use, wind circulation and even how shadows fall across buildings at different times of day,” Dr Chen says. “Urban planners use it to test zoning changes, infrastructure upgrades and even emergency response plans."

Closer to home, the Digital Twin Victoria program is building a state-wide, data-rich model of the built and natural environment.

At the University of Melbourne, the Centre for Spatial Data Infrastructures and Land Administration (CSDILA) is also building digital twins for major precincts – such as Fishermans Bend to help plan future urban developments in our city.

There are challenges

But Associate Professor Haghani says for all their promise, digital twins aren’t a magic switch.

"Building one takes time, coordination, and a lot of data. Many cities still struggle with fragmented systems: data that’s trapped in different formats, agencies, or private hands. If the inputs aren’t connected, the twin can’t function.

"There are also challenges around cost and complexity. A full-scale city digital twin—especially one that updates in real time—requires investment in infrastructure, cloud computing, and data governance. That’s not something every council or region can afford.

"Privacy and security are also real concerns. When a digital twin maps live data from energy use, public transport or movement in public spaces, questions naturally arise: Who owns the data? Who can access it? How is it being protected?"

Why now?

The idea of a digital twin isn’t new – but what’s changed is the urgency.

Cities are under growing pressure to adapt to climate extremes, population growth, infrastructure strain, and economic shifts. Decisions that once played out over decades now need to happen faster, with more confidence, and fewer second chances.

At the same time, the tools have matured.

"Advances in cloud computing, artificial intelligence, and sensor networks have made it possible to build digital twins at a city-wide scale, and to keep them updated in real time," Associate Professor Haghani explains.

"In Victoria, this shift is already underway. Through partnerships like the Digital Twin Victoria program, government and research institutions are laying the groundwork for smarter planning and better risk management.

"What’s emerging isn’t just a digital model. It’s a new way of seeing and shaping the city.

"Done well, they can make planning more responsive, infrastructure more resilient, and decision-making more informed. And as cities face increasingly complex challenges, that kind of foresight may no longer be optional. It may be the new standard, and a necessity."