# 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  
[PERSON] et al. [48] developed a system architecture for DTs designed for both building- and city-level applications. The DT architecture is structured into five layers: data acquisition, transmission, digital modeling, data/model integration, and service. The data acquisition layer forms the foundation, where various data types, formats, sources, and content must be considered. The transmission layer facilitates the transfer of acquired data to higher layers, such as the digital modeling layer, which contains digital representations of physical assets and associated metadata. The data/model integration layer, which serves as the core of the DT architecture, integrates data from all sources according to a predefined data structure. The service layer represents the implementation stage of the DT model, supporting information interpretation and facilitating interaction between users and the data/model integration layer or DT system. [PERSON] et al. [27] proposed a DT framework for emerging business models such as Car-as-a-Service (CaaS). The framework is organized into layers based on ISO 23247, including the DT, storage, communication interface, tools and utilities, HMI, and the observable asset model (OAM). The DT comprises a set of models that represent an observable asset. It includes various tools and utilities that offer functionalities accessible to applications and users, such as asset control, simulation, diagnostics, and report generation. The HMI facilitates user interaction, enabling users to visualize DTs and monitor system status. The storage layer provides data storage, which may include historical asset data for further analysis. The communication interface enables interaction between the asset and external systems. Lastly, the OAM represents the real-world assets observed by the system in constructing the DT. Observable assets may consist of a single asset or a set of assets. [PERSON] et al. [49] conceptualized a DT framework for urban management. The DT city model consists of five layers: the physical layer, data acquisition layer, data modeling layer, simulation layer, and service/actuation layer. The physical layer includes the real-world systems or entities represented by the DT. The data acquisition layer enables the automatic capture and transmission of data to the data modeling layer, where the DT of the physical asset is continuously updated. The simulation layer then processes the data within the model and transmits the results to the service/actuation layer, through which users can interact with DTs that are seamlessly connected to the corresponding physical assets. [PERSON] et al. [28] proposed a DT-based framework for the future development of smart asset management. The framework comprises three layers: the smart asset layer, the smart asset integration layer, and the smart DT-enabled asset management layer. The first layer, the smart asset layer, involves asset management activities performed using high-performance digital technologies, such as BIM and information and communication technology. The smart asset integration layer provides integration and interoperability services through IoT and network technologies, including RFID systems, QR codes, sensor systems, and cloud computing networks. Lastly, the smart DT-enabled asset management layer encapsulates the DT, integrating IoT devices, AI tools, ML models, and existing analytics systems to support a dynamic DT platform that continuously updates the condition of infrastructure assets. [PERSON] et al. [50] conceptualized a layered architecture for underground DTs. The architecture comprises several layers: the physical layer, the data acquisition layer, the communication/transmission layer, the data management layer, the data integration/modeling layer, and the application layer. The physical layer encompasses entities and processesassociated with underground construction. The data acquisition layer captures data from physical assets using various sensors.