1 Research Background of the Digital Twin City Construction Model

1.1 Initial Achievements and Coexisting Challenges in Digital Twin City Construction

A digital twin city is an effective combination of digital technology innovation and urban mechanism innovation, and is one of the important pathways to promote the comprehensive digital transformation of the entire city. Currently, China's digital twin city construction is still in the exploration phase, facing multiple challenges. First, a consensus on the path for advancing digital twin city construction has not yet been formed. Issues such as insufficient overall coordination, fragmented construction of some systems, and siloed progress in various fields persist. There is a need to further strengthen systematic thinking and form a common model for digital twin city construction. Second, the construction and operation model for digital twin cities still needs improvement. In some cities, the construction of digital twin cities is disconnected from urban business, resulting in a low input-output ratio for system construction. At the same time, China's digital twin city business model remains unclear, with a single source of funding and insufficient exploitation of the value of data elements. A sustainable operation model still needs to be explored. Third, the methods for supplying data and capabilities for digital twin cities still need innovation. Data lacks an effective standardization framework, making the fusion and application of heterogeneous data difficult. Some digital twin technology capabilities are tightly coupled with specific ecosystems, making it difficult to decouple services and reuse capabilities. Fourth, high-value scenarios for digital twins still need to be explored. Some digital twin city constructions prioritize "visual appearance" over "business mechanisms." There is an urgent need to further explore high-value scenarios for digital twin cities that are practical, effective, and enable virtual-real interaction, thereby enhancing public satisfaction and sense of gain.

1.2 Widespread Application of Industrial Digital Twin Models Abroad

In 2002, Michael Grieves proposed the "Mirrored Spaces Model," which became the prototype of the "digital twin" concept. In 2011, the U.S. Air Force Research Laboratory explicitly proposed "digital twin," and research has confirmed it as the earliest institution to propose this concept. In June 2017, Lockheed Martin introduced the "Product Digiverse" concept, i.e., "product digital twin," which has been applied in the development, production, and maintenance support of large military-industrial equipment in the United States, Europe, and other regions. In 2023, "Basic Research Gaps and Future Directions for Digital Twins" emphasized the application potential of digital twins in scientific research, industrial practice, daily life, and other fields. In recent years, international vendors such as Siemens and Dassault Systèmes have continuously promoted the implementation of digital twins, conducting application practices in industries such as factories, railways, power grids, and carbon capture. As digital twin technology matures, it is gradually being applied in the urban domain, such as Singapore's promotion of the "Virtual Singapore" project. Additionally, cities like Toronto, Canada, and Rennes, France, have also initiated digital twin city construction.

1.3 Accelerated Progress in Digital Twin Model Research in China

In recent years, both China's industry and academia have proposed perspectives on digital twin model construction, providing valuable references for building digital twin city models. In 1994, Qian Xuesen translated "Virtual Reality" as "Lingjing Technology" (灵境技术). The proposal of "Lingjing Technology" represented another technological revolution following the computer technology revolution, providing important inspiration for the establishment and development of the digital twin concept. In 2019, Tao Fei et al. proposed a five-dimensional digital twin model, suggesting that a digital twin model comprises five major dimensions: physical entity, virtual entity, service, twin data, and connection. In 2022, Tian Ying et al. proposed a City Information Model (CIM) platform framework, believing that CIM consists of three major systems: data governance, intelligent model analysis, and human-computer interaction. Zhuang Cunbo et al. proposed the connotation of a product digital twin, suggesting that a product digital twin includes five parts: product design model, product process model, product manufacturing model, product use and maintenance model, and product disposal and recycling model. In 2022, the World Economic Forum and the China Academy of Information and Communications Technology jointly proposed a "4+5" digital twin city framework, which includes four internal elements (infrastructure, data resources, platform capabilities, application scenarios) and five external elements (strategy and mechanisms, stakeholders, funding and business models, standards and evaluation, network security). Meanwhile, Tang Wenhu et al. proposed a smart energy digital twin architecture, Dong Leiting et al. proposed an aircraft structure digital twin architecture, and Zhengzhou University of Light Industry, in collaboration with the University of Cambridge, proposed an industrial digital twin system structure, all providing valuable references for constructing digital twin city models.

Overall, scholars both in China and abroad have proposed common concepts for digital twin models. However, research specifically on digital twin city construction models is scarce, and a common digital twin city model guiding the construction of cities and parks has not yet been proposed. Therefore, there is an urgent need to start from the development needs of cities and parks, construct a digital twin city construction model covering multiple dimensions such as twin data, platforms, and scenarios, and provide a reference for governments and enterprises in advancing digital twin city construction.

2 Construction of the Digital Twin City Construction Model

Based on the principles of goal orientation, guiding construction, and ease of operation, this study innovatively proposes the "Five-Dimensional Model for Digital Twin City Construction" (referred to as the "Five-Dimensional Model"). The Five-Dimensional Model is based on "Strategy and Talent," with "Business and Operations" as a long-term guarantee, "Facilities and Data" as the foundation, "Technology and Platform" as the core, and "Applications and Scenarios" as a key lever. It aims to promote systematic planning, high-quality construction, and sustainable development of digital twin cities (see Figure 1). The Five-Dimensional Model is applicable to the construction of holistic digital twin cities, such as large, medium, and small cities, as well as regional digital twin city construction, such as parks and urban functional areas. In line with the "Guiding Opinions on Deepening Smart City Development and Promoting the Comprehensive Digital Transformation of the Entire City," the five major dimensions of digital twin city construction can be divided into two levels: the "Urban Digital Foundation Infrastructure Project" and the "Digital System Reform and Innovation Project." These two levels drive the construction of digital twin cities through dual-wheel innovation in technology and institutions, empowering the comprehensive digital transformation of the entire city.

3 Implementing the Urban Digital Foundation Infrastructure Project to Strengthen Digital Twin City Technical Capability Support

3.1 Facilities and Data Dimension

3.1.1 Build an Integrated Urban Sensing System to Strengthen the Sensory Nerve Endings of Digital Twins

First, strengthen the co-construction and sharing of urban sensing facilities, promote the integrated construction and intensive sharing of urban sensing facility carriers, advance the "multi-pole integration" of sensing devices such as lighting, transportation, security, communication, and environmental protection, and create pilot demonstrations such as smart poles. Second, promote the unified management of urban sensing terminals, facilitate the establishment of urban sensing terminal ledgers, and achieve the census and unified coding of urban sensing terminals. For example, Beijing promotes the unified coding of urban sensing devices, enabling refined management of various sensing terminal equipment. Third, promote comprehensive coverage of the urban sensing system, advance the deployment and upgrade of sensing facilities in urban above-ground, underground, air, and water spaces, and create a new urban sensing system characterized by "data interconnection, IoT interconnection, and intelligent interconnection."

3.1.2 Improve Urban Network and Computing Power Facilities to Solidify the Foundation for Digital Twin Transmission and Computation

First, strengthen the construction of communication infrastructure, promote the extended coverage of fiber optic networks, 5G networks, etc., and provide high-speed, stable network support for all urban areas. Second, strengthen the popularization and application of the Internet of Things (IoT) to provide reliable network support for sensing data collection. For example, use sensors, cameras, and other devices to collect real-time data, providing real-time information for the efficient operation of digital twin cities. Third, build a cloud-edge collaborative computing infrastructure to enhance urban computing capabilities, supporting large-scale data processing and real-time simulation analysis. For instance, cloud computing centers can centrally process large amounts of data, providing powerful computing capabilities; edge computing can perform preliminary processing at the data source, reducing network latency and improving response speed.

3.1.3 Innovatively Construct Urban Digital Twins to Promote the Digital Expression of All Urban Elements

First, innovate data organization methods, using physical objects as the core to construct urban digital twins. Urban digital twins are conducive to promoting cross-domain data fusion, improving data management efficiency, and fostering innovation in digital twin applications. Cities at all levels can start from the needs of scenarios such as urban governance and public services, targeting physical objects like buildings, natural landscapes, roads, and bridges. By using methods such as oblique photography and intelligent modeling, they can collect and fuse multi-source data to form digital twins that map to the physical city. For example, in a digital twin building scenario, models such as building twins, equipment twins, and server room twins can be gradually built based on scenario requirements. Second, promote multi-source data fusion to create diversified urban data services. Using digital twins as a lever, promote the correlation and fusion of geospatial data, socio-economic data, IoT sensing data, etc. In the future, digital twins can be published as machine-readable web services, making it easier for enterprises and the public to access data services.

3.2 Technology and Platform Dimension

3.2.1 Build an Urban IoT Sensing Platform to Improve Real-Time Data Processing Capabilities

First, build an urban IoT sensing platform to achieve the fusion and sharing of sensing information. Fully leverage existing smart city platform foundations to establish an urban IoT sensing platform, enabling real-time acquisition of various IoT sensing data related to urban water, electricity, gas, transportation, environmental protection, public security, meteorology, etc. Through statistical analysis of urban operation indicators, support early warning and decision-making, achieving dynamic monitoring, early warning decision-making, and remote control of regional facilities and equipment. Second, create sensing data sharing service interfaces to support various management and service applications. The IoT sensing platform can provide standardized sensing data sharing service interfaces, constructing a city portrait integrating urban imagery and urban characteristics, providing data support for urban management and public services.

3.2.2 Build an Urban Digital Twin Model Platform to Achieve Digital Expression of All Elements

First, build an urban digital twin model platform to promote the spatial alignment and fusion of multi-source data such as urban population, housing, economy, and events. Utilize technologies such as graphics rendering and human-computer interaction to present digital twins of different precisions and types on various terminals, including large, medium, and small screens. Second, promote the asset-based management of urban digital twin data, establish a full lifecycle management mechanism for the aggregation, construction, application, and sharing of digital twins, and provide functions such as personalized editing and interactive operations, offering efficient data support for various applications like digital twin city management and services. Promote the asset-based management of digital twin data, including natural resource data, geographic information data, 3D model data, and real-time operation data, and create a number of high-quality industry datasets.

3.2.3 Build an Urban Data Intelligent Service Platform to Drive Urban Business Reform and Innovation

First, provide multi-dimensional data analysis and computing capabilities. For various attribute data of urban digital twins, promote the fusion analysis of urban spatiotemporal location information, operational status information, and entity relationship information, assisting in scientific urban decision-making. Second, provide intelligent analysis and computing capabilities. Promote the application of technologies such as artificial intelligence algorithms, large models, and intelligent agents in areas like urban traffic management, energy management, and emergency management. Strengthen the intelligent analysis of urban data to achieve intelligent analysis and computing of all urban data elements, processes, and lifecycles. Third, provide scenario simulation and deduction capabilities. Based on the digital twin environment and historical data, conduct simulation deduction and intelligent prediction of urban information such as pedestrian flow, traffic flow, and energy, enabling data-driven business innovation.

3.2.4 Build a Scenario Opening and Innovation Platform to Enable Open, Low-Barrier Scenario Construction

First, build a scenario opening and innovation platform to promote the opening of urban digital twin data, models, and scenarios to the public. Enterprises and individual developers can use the platform's capabilities to achieve low-barrier, drag-and-drop scenario construction, supporting urban scenario innovation. Second, promote the circulation and sharing of innovation resources. Use the opening and innovation platform to aggregate a number of capability engines, typical scenarios, and solutions from the digital twin industry, creating an online case library and toolbox for digital twin cities. This promotes the matching of supply and demand and project implementation in the digital twin field, fostering the cultivation and growth of the urban digital economy.

3.3 Application and Scenario Dimension

First, establish a scenario construction mechanism consisting of five key stages: "scenario list - open competition for project selection - government-enterprise co-construction - effectiveness evaluation - brand building." This promotes government-enterprise cooperation, scenario opening, and collaborative innovation. Second, plan a number of inclusive and convenient public service scenarios to lower the barrier to using digital twin technology, providing the public with equitable, friendly, and convenient twin services. For example, use virtual reality technology to conduct teaching experiments in physics and chemistry; use augmented reality and virtual-real interaction to enhance cultural tourism service experiences; and use digital twin platforms to make public services like healthcare and education accessible to more people. Third, plan a number of precise and efficient governance scenarios. Use digital twin technical means to achieve a "single-map" presentation of urban operational status. Through real-time monitoring and simulation prediction, assist in urban energy conservation and emission reduction, quickly respond to urban public issues, and improve urban safety and resilience. Fourth, plan a number of cost-reducing and efficiency-enhancing business scenarios. Promote the construction of scenarios such as digital twin workshops and digital twin factories, enabling functions like unmanned operations, remote inspection, and remote control. Form a green, intensive, and efficient development model, promoting the coordinated development of urban digital construction and the digital economy.

4 Implementing the Digital System Reform and Innovation Project to Enhance Urban Digital-Ready Institutional Guarantees

4.1 Strategy and Talent Dimension

4.1.1 Conduct In-depth Research on the Current State of Urban Development and Scientifically Formulate Strategic Plans

First, conduct in-depth investigation and research to deeply grasp the current state of urban policies, economy, society, technology, and urban characteristics, and ascertain the baseline of urban digital development. Second, scientifically prepare plans. Based on urban strategic deployments and industry standards and specifications, combined with the direction of technological development, formulate high-standard, customized digital twin city plans, providing policy support for technology selection and project implementation. Third, promote implementation in an orderly manner. Form actionable and operational implementation plans. In the short and medium term, take the lead in promoting the implementation of a number of digital twin scenarios that solve common urban problems, pain points, and achieve significant results. In the long term, maintain the flexibility and inclusiveness of the construction framework and implementation path to promote the sustainable development of the twin city.

4.1.2 Focus on Training for Key Positions and Build a Composite Talent Pipeline

First, build a composite, tiered digital twin talent team. Construct a closed-loop talent cultivation system covering "university training - skills training - capability certification." Develop digital skills training programs at different levels and for different specialties, and directionally supply talent in areas such as digital twin facilities, data, platforms, and applications. Second, focus on talent training for key digital positions. Pay attention to the cultivation of talent for key positions such as Chief Data Officer and Chief Technology Officer, enhance the ability of organizational digital leaders to use digital technology to solve problems, and provide talent guarantees for the construction, management, and operation of digital twin cities.

4.2 Business and Operations Dimension

4.2.1 Clarify the Roles and Positioning of Relevant Stakeholders and Innovate the Government-Enterprise Collaboration Organizational Structure

First, clarify the operational management structure of the digital twin city. Government departments, as the overall managers of the digital twin city, should leverage their advantages in overall coordination, organizational leadership, and supervision and management. Social entities, as contractors or co-investors, should cooperate in the construction of the digital twin city. Through government-enterprise cooperation models for construction and operation, ensure the orderly progress of digital twin city construction. Second, establish a digital twin co-construction ecosystem with complementary advantages and collaborative innovation. The main entities involved in digital twin city construction include enterprises in fields such as urban planning, modeling and simulation, visualization rendering, sensing identification, and interactive control. Enterprises in various industries need to focus on division of labor and collaboration, providing necessary products and services for digital twin city construction. Through forms such as resource exchange, project cooperation, product joint operation, and joint development, create a good ecosystem with complementary advantages and collaborative innovation. Third, build a digital twin project evaluation mechanism. Establish an evaluation indicator system that accurately reflects the level of digital twin city construction, regularly conduct evaluations of digital twin city projects, and achieve "promoting construction through evaluation, and promoting excellence through evaluation."

4.2.2 Promote the Value Development of Data Elements and Explore Sustainable Operational Business Models

First, use data to drive the optimization of urban governance models. Fully utilize technologies such as digital twins and artificial intelligence to provide effective data support for urban governance, enhancing the city's ability for intelligent decision-making and optimal resource allocation. Second, through models such as sharing 3D digital twin models, providing digital twin platform software as a service, and customized data development, promote data operations, capability operations, platform operations, and scenario operations for digital twin cities, fostering the long-term development of the twin city.

5 Strategic Recommendations

The Five-Dimensional Model for Digital Twin City Construction provides directional guidance and a common framework for various regions to advance digital twin city construction. However, regions still face challenges in areas such as classified construction of digital twin cities, scenario construction, and ecosystem cultivation. This study proposes recommendations including classified policy implementation, characteristic leadership, and ecological collaboration to provide a reference for advancing digital twin city construction.

5.1 Implement Classified Policies to Advance Digital Twin City Construction

First, regions with a good digital foundation should highlight benchmark leadership, build a leading digital twin foundation platform, innovate in twin construction and scenario application, and promote platform co-construction, data sharing, and capability reuse. Leverage first-mover advantages in technology and applications to cultivate the digital twin industry, forming a radiation-driven effect. Second, regions with a moderate digital foundation should highlight stable development, moderately or pilot carry out work such as scenario innovation, data fusion, and technology platform construction to achieve steady upgrades. Third, regions with a weak digital foundation should highlight replication and promotion. Fully learn from the experience of regions with a good foundation, select application areas with high maturity and good application effects, and carry out digital twin city construction to avoid detours, save investment, and achieve results quickly.

5.2 Lead with Characteristics to Create Pioneering Digital Twin Scenarios

First, on the government side, based on the city's resource endowment, industrial characteristics, and major needs, create a number of characteristic demonstration scenarios for digital twin cities, forming a positive cycle where digital twins empower high-quality industrial development. For example, port cities can build digital twin ports to improve the management efficiency of automatic marshalling and transportation scheduling, empowering port business development. Industrial cities can build pilot demonstrations of digital twin factories and digital twin workshops to promote full lifecycle product management, empowering industrial development. Second, on the enterprise side, based on scenario needs in different regions, create a number of industry-leading and replicable twin city solutions. Focus on areas such as urban intelligent agents, urban lifelines, and large model applications to create a number of practical, effective, and industry-leading pioneering digital twin city scenarios.

5.3 Foster Ecological Collaboration to Create a Co-construction and Sharing Development Pattern

First, fully leverage the role of digital twin industry alliances and industry associations. Guide leading enterprises to carry out collaborative research on key technologies such as 3D modeling, spatial computing, and virtual-real interaction, promoting industrial collaboration and independent innovation. Second, build a high-level public service platform for digital twin cities. Rely on third-party associations, alliances, think tanks, etc., to build a public service platform for digital twin cities oriented towards industrial development, improving the efficiency of industrial resource utilization and business response speed, and cultivating a number of leading digital twin enterprises. Encourage more enterprises to continuously launch high-quality digital twin application products, empowering the high-quality construction of digital twin cities and contributing to the development of the digital twin industry.

6 Conclusion

Digital twin cities have become an important lever for promoting the comprehensive digital transformation of the entire city. This paper innovatively proposes a Five-Dimensional Model for digital twin city construction, providing a valuable reference for governments and enterprises in advancing digital twin city construction. In the future, combined with urban development needs and technological evolution trends, the research on the digital twin city construction model will be iteratively improved to promote the high-quality development of digital twin cities and contribute to the construction of Chinese-style modern cities.