# Seeking a Definition of Digital Twins for Construction and Infrastructure Management
## 5 Defining and Standarising the Concept of a Digital Twin for the Built Environment
### Education and Training  
Developing a complete digital twin environment involves many technologies. The general management of a digital twin demands a multidisciplinary profile. Inside the digital twin, we can find different objectives, such as 3D representation, data simulations, or data hosting. According to the main functionalities inside a digital twin, Figure 4 details the different objectives inside a DT and a training proposal according to them.  
Figure 4: Main technologies and their relationship between them inside a DT.  
Based on Figure 4 different technologies can be considered as a part of a DT. If the DT requires a 3D representation, technologies and the methodologies associated to the building information modelling could help to achieve not only a virtual representation but a geometrical and cyber-physical database. If a more realistic visualisation is desired, specific visualisation tools could be implemented. Some tools are totally interoperable with BIM software, making it easier to achieve renders of the infrastructure modelled. Moreover, parametric modelling is also a quite interesting tool, especially on initial project phases, when quick cost-estimation or material quantification is needed.  
Data management is probably the most important part of any DT. Depending on the final purpose of the DT, the existence of 3D models, or even the software implemented, the methodology used to manage data might differ. Moreover, in many cases, the most common issues are related to interoperability. Some BIM software codes are currently in demand as they enable a user-friendly interaction with the 3D models. They cater important parameter management tools avoiding the modelling of repetitive parts of the infrastructure or even enable advanced virtual representation functionalities. In this sense, data management could be improved with visual programming tools or even different programming languages which might be connected to BIM models.  
Another possible way of visualising the 3D models is by applying the technologies that currently stand out mostly in video games, such as augmented reality or virtual reality. Even in a DT, the most common programming languages are left aside in order to use platforms such as Unity or Unreal Engine. These tools provide a great immersive metaverse of the infrastructure and its environment but, as of now, its everyday use is limited.  
It should not be forgotten that a DT is a live entity, and validity depends on its updates. For that task, the state of the DT is updated by a myriad of sensors which employ IoT technology and might provide the real time data of the infrastructure and environment. The IoT could be divided in two main parts inside the DT: (1) IoT devices and (2) data management. Regarding the IoT devices, it is necessary to deploy them and define a communication protocol, such as with MQTT data or a LoRa network. However, after defining it, it is necessary to establish the communication process inside the DT. In this sense, the development of internal API for connecting online platforms and IoT devices could be considered a suitable alternative.  
All these skills have been traditionally taught in several undergraduate and graduate degrees which have no common ground. Consequently, a new syllabus had to be created to provide proper competences to the required labour force. The Executive Master in Digital Twins for Infrastructures and Cities is a clear example of these new programs. This Degree is promoted by several highly-ranked European Engineering Universities: Universidad Politecnica de Madrid, Ecole Nationale des Ponts et Chaussees, Budapesti Muszaki es Gazdasagtudomanyi Egyetem, and the National University of Science and Technology Politechnica Bucharest. The Degree provides interdisciplinary training in digital skills (AI, data science, BIM, cloud computing, language programming, etc.) and DT implementation (management of DT, design and deployment, etc.). This kind of training fills the current need for DT profiles in the AECO sector.