Towards City Digital Twins

This year there has been increasing discussion and action on the application of Digital Twins for cities, states and nations. The ideas of Digital Twin's are by no means new, with well established practices in manufacturing, avionics and product development stretching back to the 1970's. What has changed is application of the Digital Twin ideas and practices from products and assets to cities, nations and units of government. This is a brief summary of ideas and thinking on a fast developing subject, from the perspective of a public servant learning about both the potential and the application of these ideas.

What are Digital Twins?

Digital Twins are the idea that we can reflect and merge objects, processes and systems from our lived reality into the digital world to create understanding, power collaboration and achieve better outcomes. As a concept Digital Twins come from making and running products and assets, however as technological capability has grown these ideas are now being developed and applied to much larger scale and more complex units based on geographies and jurisdictions, such as cities, states and nations. Whilst well established definitions exist for manufacturing based twins, those for cities and nations are still developing. Of those twins that do exist or under development they can be divided (imprecisely) into Component, Asset, System and Process based twins. The following slides outline the characteristics and examples of these types

The arrangement and fusion of these types into city (and national) twins results in twins that based on a combination of geography, jurisdiction and mandate. This results in city twins have key factors such as:

• Federation- There are many different people and organisations which have a stake in a city, each with a data footprint that needs to be shared within a trust mandate and standards framework for a true city twin to work
• Scale- Cities are large, complex assemblies of systems, this means City Twins tend to involve a great deal more different technologies than the original product based Digital Twins
• Immaturity- Digital Twins are at the cutting edge of city technology, with cities exploring what they are, why they matter, and how to catalyze their creation.
• Continuity- Cities have long pasts and futures, this creates challenges and continuity problems in absorbing the past and accounting for futures in the creation of City Twins
• Democracy – Concepts like Digital Identity, Digital Inclusion and Digital Government are vital to the success of City Twins supporting our democratic institutions and the evolving relationship between citizen and government.
• Strategy – City Twins provide considerable operational advantages for city governments, but their greatest value is to transform the way cities can confront strategic issues such as climate change, wellbeing and resilience.
• Roots - at its heart the digital twin is an extension of the same ideas which underlying GIS, BIM, Asset management and other technologies city governments have traditionally been leaders in - what has changed is the ability to scale and communicate these ideas across organisations and the city.
• Diversity- City's are very complex places - and their public institutions often have a wide variety of interlinked yet culturally distinct functions. This diversity requires City Twins to function across many different silos of expertise, whilst ensuring that common principles like privacy by design are followed.

A City Twin is the digital reflection of a living city, its institutions, systems and component parts. It allows for the reflection, convergence and merging of the physical and digital worlds to harness the ability to analyse, optimise, communicate and simulate in Digital Space, and use those abilities to understand, activate and transform in our living world.

How Do Digital Twins Work?

A city digital twin can divided into four layers:

-       Data – The acquisition and storage and sharing of data that the city twin is made from. This covers the data journey from the person interacting with the device, the sensor or data acquisition (e.g. Lidar Scan) to the place where the data is stored. For example – the 3D Buildings data for Wellington

-       Collaboration – The combination of Council Data with that of other people/organisations. This covers the open and shared data portals, and data governance that makes data available from, between and to other parties. E.g.- the digital terrain outside the city comes from LINZ as Open Data from the NZ Government.

-       Transformation/Use – The transformation of data into information or action either through analysis, decision support technologies like Machine Learning or via Machine to Machine protocols (e.g. turn on the streetlights when it gets dark). The conversion of the 3D Buildings Data from GIS to Gaming Technology

-       Expression – The communication of the information or status of action through a technology, e.g. through Virtual Reality, a Map, a Dashboard or other medium. This is where the information management governance takes place. E.g. A Digital City Model Virtual Reality Experience

A Digital Twin is not a single object or computer program, but rather is a way of understanding how places, people and institutions relate using both real and digital space to create change in a place. Digital Twins can exist in parallel - with each entity/agency building from the same federated data and adding its own capabilities to the different layers.

Why Are Cities Interested in Digital Twins?

The institutions associated with cities such as Local Governments, Utility Operators and Service Providers are generally interested in Digital Twins for a variety of reasons including:

• Understanding- Digital Twins help use technology to both understand the performance and potential of an asset, but also to put it into context with the people, economy's and ecology's it is serving
• Collaboration- City's are messy, tangled places - Digital Twins allow for data to be brought together to bring insights across jurisdictions and silos- for example understanding how health and safety of citizens interlink with the city's physical environments or the relationship between conservation and urbanization
• Unification- Local Governments are by their definition place based institutions - this means they generally have a wide and diverse set of functions. By understanding how the footprint of the organisation, key stakeholders and citizens fit together a more effective transparent and unified form of local government can develop
• Strategy- The great challenges of our time require both adaptive mindsets and institutions if cities are to be resilient and thrive. Climate Change, Economic/Social Iniquity and Democratic development are all evolving as key challenges for cities globally, and the ability for digital twins to change the way infrastructure and engagement performs makes them a priority for many governments in the future.

Are We There Yet?

At present it is hard to know for certain if you have achieved a digital twin of your city - there are standards but these are generally based on manufacturing contexts rather than on the institutional/city scale. At present most city's and their governments seem to be still in the early stages of their digital journeys. Like many learning processes digital city twin practice can be thought of as a journey. At present this journey seems to have three stages:

Generation One - Experimentation – Beginning the understanding of what a City Digital Twin is, and how it might be done. This stage is generally marked by an emphasis on creating a digital replica of the city’s physical structure and by being pilot based. Generally this stage is based heavily on 3D GIS and asset twins in the infrastructure sector.

Generation Two – Capability Development- The understanding of Digital Twin develops from the replication of physical things to understanding the organisations digital footprint, engagement and processes. This sees a move from a pilot based way of working towards digital dividends and consciously converging work programmes to provide sustainable, shareable, useable data streams.

 Generation Three – Continual Development – Digital Twin becomes a consciousness of an organisations digital footprint and is used across that organisation as an infrastructure of collaboration.

Where Can I Learn More?

Digital Twins can be difficult to understand given the swift development of the ideas in at the city scale. Some places to look are:

• The ANZ Digital Twin Hub
• Digital Built Britain
• Unlocking the Value of Data
• Digital Twin Guidance Note - ANZSCC
• The Open Data Institute

Conclusions

Digital Twins are not a new idea, but their application to cities and jurisdictional scale systems is. In many ways a Digital Twin represents the integration and operationalisation of the ideas which sit behind a smart city, using GIS, BIM, the Internet of Things, Machine Learning and many other technologies within its constituent layers. Most importantly the Digital Twin idea for cities represents a consciousness of the ability of the fusion of digital and physical to make cities more adaptive, equitable and resilient places to live.

This article was drafted to help set out my view of City Digital Twins- I have done my best to keep a potentially complex area simple and understandable. I freely acknowledge the many people with different ideas and experiences about how City Twins evolve. I aim to write a small collection as this understanding develops and changes - next time- Why Digital Twins? Barriers and Incentives in Twinning.