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Digital Twin: Potential for Smart Cities

Using the example of our demo "Moving Hamburg"

Digital twins are increasingly used to perform analyses and scenarios digitally before they are applied in the real environment. We have built a demo that combines a 3D image of the city of Hamburg with the public transport network. In this way, we show how digital twins can be implemented technically. And what benefits they have in the context of the smart city.

Video of the demo: "Moving Hamburg": By using WebGL a 3D view is possible. The maps can be rotated manually in the demo and tilted by pressing shift while moving the mouse pointer.
View the full demo

The benefit of digital twins

With digital twins, we can create realistic representations of our world that enable analysis and planning scenarios that would not be feasible in the real world. Thanks to advanced technology, digital twins are increasingly being used in various industries with diverse use cases. According to a study by ABIresearch, more than 500 cities worldwide could be using digital twins as early as 2025.

Keeping in mind that public transportation plays a central role in livable and sustainable cities, let's focus on bus, rail and metro. Let's imagine we want to divert traffic from three bus routes for a day to measure the impact on the concentration of nitrogen oxides in the air. In the real world, the scenario involves enormous effort. Digital twins, however, enable a realistic simulation on the computer and can thus provide valuable insights for implementation in reality. The "Smart City" topic area offers a particularly large number of use cases here. The digital networking of road users, intelligent traffic control and guidance of visitor flows are already an important part of urban planning today and will become even more of a focus in the future.

One demo - many use cases for digital twins

With our demo "Moving Hamburg" we built a digital twin of the city of Hamburg on which the stops, travel times and routes as well as accessibility of public transport can be traced. In short, the demo shows a digital image of public transport in Hamburg. We see real data from the GTFS database (General Transit Feed Specification). The representation of the city in three dimensions, combined with public transport data, is just one of many ways to use digital twins. Combining real-time mobility data in the context of a 3D city model creates a meaningful representation with potential for many other use cases:

  • Planning scenarios in the real estate sector: How do construction changes affect the flow of traffic or evaluation of real estate locations, based on connection options for local traffic or crime statistics.
  • Major events (e.g. marathon): Where are the groups on the marathon route, where can the route be crossed, where does traffic have to be diverted?
  • Events (e.g., Long Night of the Museums): Where are the crowds at their peak? Visitor control through mobility offers based on demand. Mobility offers in the Smart City: Precisely tailored mobility offers can be offered on the basis of accessibility analyses.
  • Visitor orientation (e.g., clinic): A 3D representation of the site with live data on departures and means of transportation simplifies orientation for guests in large operating plants, at airports, or on the grounds of a clinic.

Structure and design of the demo

The basis of our demo is the Google Maps API WebGL with 3D features. With this we create a realistic and complete representation of the world - in this case the road network in Hamburg. On top of this we have drawn a data layer with the GTFS data. For an additional data layer about the accessibility of HVV stops and means of transportation, we read accessibility polygons from third-party providers. The integration of WebGL and Three.js allow us to display the map in a performant way despite large amounts of data. Additionally, we ensure a tidy and user-friendly design with the following design decisions:

  • The map as a drawing background: using muted colors and a minimalist design, we reduce the map to the bare essentials to serve as a frame of reference for our data. 
  • Rendering data and map on one layer: The data is rendered into the same WebGL context as the map using three.js. This merges the data with the map. For example, subways can pass behind a building that obscures the route. The animation is calculated from information about the timetables, the stops and the intervening routes.
  • Different levels of information: Different levels of information provide a clear and intuitive design. At low zoom levels, the map provides an overview of the transport network and reduces the display to the most necessary information. At this level, the route network is displayed abstractly and thinned out, and animations are played faster to provide a temporal overview of local transport travel times. Zoomed in, more details are displayed on the map and the information density is increased. Buildings are displayed as detailed 3D models and animations run at a slower playback speed appropriate to the level of detail. The level of information density increases with the level of detail on the map. In this way, users are not overwhelmed by the information. 
  • Good user experience: The technological innovations enable fluid use of the demo thanks to appealing 3D maps and coherent transitions between the individual information levels.

Click here for the demo "Moving Hamburg":

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