Imagine exploring a city and simulating urban interventions with just a few clicks. This is the promise of local digital twins—a virtual mirror reflecting the heartbeat of urban spaces. In a world where the availability of data offers us valuable insights, these digital replicas offer cities a powerful lens through which to envision their future and navigate the complexities of modern urban life.
Understanding local digital twins
“At a general level, one of the great benefits – as well as one of the great challenges – of local digital twins is their ability to gauge the pulse of the city, serving as a tool for urban decision-making,” explains Patricio Reyes, Researcher at the at the Data Analytics and Visualisation Group at the Barcelona Supercomputing Center.
Local digital twins serve as virtual replicas of cities, akin to expansive sandboxes where urban planners and policy makers can experiment with different scenarios and strategies.
Much like an open lab, users can manipulate data within the digital twin environment to simulate hypothetical interventions, test out innovative ideas, and explore potential outcomes.
This virtual ‘trial and error’ approach has the potential to revolutionise urban planning by providing a dynamic platform for evidence-based decision-making. “Local digital twins should be conceived as a tool seeking honesty, integrating various layers of information,” adds Reyes, “which ensures that decision-making processes are evidence-based, granting them a higher degree of transparency and traceability.”
Building a digital twin
Developing and implementing a local digital twin involves gathering diverse city information and creating models that generate relevant insights. “Given its impact on public policies, the urban planner, and by extension the local digital twin, need to have a broad and diverse vision of the city,” says Reyes.
Given its impact on public policies, the urban planner, and by extension the local digital twin, need to have a broad and diverse vision of the city.
The process begins with collecting all the valuable information that will allow the platform to comprehend the city dynamics as a whole. This includes the information collected by sensors deployed within urban environments. These sensors can monitor a wide range of parameters relevant to city life, such as air quality, traffic flow, noise levels, temperature, humidity, and more. This data is used to gain insights into various aspects of urban living, including environmental conditions, transportation patterns, infrastructure usage, and public health.
However, sensor data is not enough. “In our approach, understanding the perspectives and desires of city residents is essential. The diversity of information allows us to tackle problems from various angles,” emphasises Reyes. This inclusive approach ensures that the digital twin reflects the multifaceted dynamics of urban life. “Also, as with any data-based project, it is important that users are aware of the potential bias they could find in the available data. That is why our approach to local digital twins includes a proper data audit and report.”.
In addition to information, the other key component of local digital twins are the models, representations or simulations of various aspects of the urban environment and its systems. “Models essentially provide relevant observations based on collected information,” explains Reyes.
Understanding the perspectives and desires of city residents is essential. The diversity of information allows us to tackle problems from various angles.
All this is presented on a platform where the urban planner can interact, pose questions, and generate ‘what-if scenarios’ to review their implications for the city. This is where the third component of the digital twin comes into play: the people that interact with it. Urban planners and policy makers can utilise the digital twin to simulate multiple intervention possibilities.
“Citizens, through participatory processes, can provide their vision of the desired city, which is then incorporated into the local digital twin,” adds Reyes.
Human centricity and transparency
The effectiveness of local digital twins relies on the integration of various data sources and technologies. This is a crucial issue that should be woven throughout the entire process of local digital twins development.
“At the Eurocities Digital Forum held in Rotterdam a few weeks ago, emphasis was placed on ensuring that digitalisation is people-centric,” highlights Reyes. “This entails, for example, recognising that people need to understand the decision-making processes in their city.”
Initiatives such as the Algorithm Register, driven by Eurocities, aim in that direction. “Local digital twins models must be as transparent as possible to citizens to allow community auditing of the process,” asserts Reyes. “Transparency plays a fundamental role here.”
Furthermore, the concept of data privacy and security plays a crucial role in local digital twins development and use. “When developing the digital twin, we need to define which questions we’d like to pose; personal data is not needed to know where to build green spaces,” elaborates the researcher. In this sense, the General Data Protection Regulation ensures that personal data is handled responsibly, safeguarding the privacy rights of city residents.
When developing the digital twin, we need to define which questions we’d like to pose; personal data is not needed to know where to build green spaces.
A multipurpose tool
Many cities are leveraging local digital twins to enhance urban environments. Such is the case of traffic control centres, which stand out as impactful examples. These centres utilise technology to understand congestion issues and offer solutions to citizens.
For example, the DUET project in Flanders developed a traffic model that calculates what traffic volumes can be expected simultaneously in the surrounding streets when one or more roads are closed. The interaction between the traffic model and the air quality model allows for the simulation of the effects of local traffic measures on mobility and the environment.
Bologna is applying the digital twin in three sectors: mobility, energy, and climate change. In mobility, they are focusing on analysing data from sensors and qualitative social data to support the development of cycling and tram infrastructure.
Barcelona has used its digital twin to assess if the city complies with the 15-minute city model, influencing how metro lines are planned and designed.
Moreover, digital twins have been instrumental in disaster preparedness and response, enabling cities to simulate emergency scenarios and develop effective evacuation plans.
Looking ahead
“In the future, I would like to see the adoption of local digital twins by cities being democratised,” wishes Reyes. This means that digital twins are understood within the process of “thinking the city,” and not only as a fashionable technology.
In the future, we hope to influence the wider community towards understanding that smart cities are those that make informed decisions with and for their citizens.
To achieve this democratisation, shifting the paradigm to prioritise citizen-centric decision-making over sensor abundance is key. This vision aligns with the ethos of Eurocities, advocating for digitalisation centred on people.
“In the future, we hope to influence the wider community towards understanding that smart cities are those that make informed decisions with and for their citizens,” concludes Reyes.
As technology continues to advance, the potential of local digital twins in shaping the urban landscape is immense. From enhancing infrastructure planning to fostering community engagement, digital twins are poised to redefine the way cities are managed and developed
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To discuss the benefits of local digital twins, an interesting workshop is being prepared within the framework of Eurocities Academy. As part of the vCity project, in collaboration with Eurocities and BSC (the National Supercomputing Center of Spain), this workshop is tailored to urban planners and policymakers. This initiative will take place in the Barcelona Supercomputing Centre’s Headquarters on 7-8 November 2024, co-located with the Smart City World Expo in November in Barcelona.
Applications for the training are now open. Check out all the information here and fill in this application form before 31 May.
