# Digital Twin Framework for Road Infrastructure Management
## 4 Digital Twin Framework for Road Infrastructure Management
### Analysis of Existing DT Frameworks for Road Infrastructure Management
#### 4.1.4 Other Applications in Civil Infrastructure and Urban DTs
The communication/transmission layer transfers these data to the data management layer. In the data management layer, data are stored, processed, and fused from multiple sources, enabling preliminary analysis. The data integration/modeling layer maintains a virtual model that incorporates various characteristics of underground environments, including semantic information and engineering properties. Finally, the application layer offers a range of functions, including model integration, statistical analysis, monitoring, and various simulation and analysis tools. [PERSON] et al. [51] proposed a DT system architecture for emergency management of civil infrastructure. The architecture comprises five layers: the physical layer, data layer, digital modeling layer, service layer, and user interaction layer. The physical layer captures information from civil infrastructure using various sensors and transmits it to the DT system. The data layer stores infrastructure-related data, including real-time sensor data, IoT data, and GIS and BIM data, as well as historical records. The digital modeling layer creates virtual representations of physical assets and may incorporate a city information model (CIM), BIM, asset information model, and agent-based model. These models can be used for various purposes, such as real-time control, scenario modeling, and decision-making support. The data/model integration layer is a core component of the DT architecture, performing multiple functions powered by AI and ML. These functions include data fusion, data analysis and querying, data/model integration, data processing, and visualization. The user interaction layer, positioned at the top of the DT architecture, facilitates interaction between users and the digital environment. UIs can include web portals, mobile platforms, and virtual reality (VR)/augmented reality (AR) applications. [PERSON] et al. [52] proposed an orthogonally synchronized DT model as part of a strategic roadmap for synchronized construction management under the Construction 4.0 paradigm, aiming to improve existing construction management practices. The framework consists of five layers: the physical infrastructure layer, the sensing and tags layer, the interoperation module, the digital layer, and the service layer. The infrastructure layer includes smart construction objects, such as workers, machines, materials, and a smart work environment. Data from these objects are acquired through various sensors and tags, including RFID, iBeacon, ultra-wideband, ultra-high frequency, and GPS. These data are then interpreted, defined, configured, and executed according to operational requirements. The digital layer incorporates DTs, smart synchronization mechanisms, AI-based decision support functions, and a cloud computing environment. These components support various applications in the service layer, including real-time supervision, positioning, and data visualization, as well as dynamic control services such as operation error alerts, automatic task navigation, and pre-construction simulation. Stakeholders receive real-time feedback and can make informed decisions based on the information provided. Table 4 summarizes the findings from DT layered approaches in other DT applications across civil infrastructure domains, including urban DTs and construction management. In Section 4.1.4, we conducted a thorough examination of seven selected papers related to various aspects of civil infrastructure and urban DTs. The reviewed papers primarily focused on DTs of cities, smart cities, urban DTs, smart asset management (e.g., buildings), underground space DTs, infrastructure emergency management, and future construction management. These papers were included alongside those related to road infrastructure networks, bridges, and tunnels to ensure that the proposed framework is comprehensive and that the road infrastructure DT layers are consistent with those of other civil infrastructures and urban DTs.