## 6 Current Applications of DTs in Transportation Infrastructure  
DT technology has found applications in several fields within transportation infrastructure and has greatly enhanced the approach through which cities plan, manage, and maintain their networks. The architecture of a digital twin platform for urban transportation, as illustrated in Figure 4, integrates industry applications, platform services, visualization, simulation-based deduction, IoT devices, and supporting platforms to enable  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Lifecycle Phase** & \multicolumn{2}{c}{**Key Focus and Activities**} & \multicolumn{2}{c}{**Key Benefits**} & **Selected References** \\ \hline Planning and Design & - & Multi-dimensional modeling and & - & Multi-dimensional modeling and & \\  & high-fidelity simulation & - & high-fidelity simulation & \\  & - & Integrated data (traffic flow, weather, & Integrated data (traffic flow, weather, & \\  & environment) for design decisions & - & environment) for design decisions & [34; 62; 64; 65; 66; 67; 68; 69; 70] \\  & - & Scenario evaluation, multi-objective & - & Scenario evaluation, multi-objective & \\  & optimization, and collaborative design & & optimization, and collaborative design & \\ \hline Construction and & - & Real-time construction monitoring & & \\  & (progress, resource usage) & - & Reduced human errors and delays & \\  & - & Risk prediction and on-site safety & - & Improved resource allocation and safety & \\  & management & - & Proactive risk mitigation and & \\  & - & Quality control with BIM and & & continuous quality assurance & \\  & sensor data & & & \\ \hline Operation and & - & Real-time traffic monitoring, dispatch & - & Decreased congestion and improved & \\  & - & optimization, and incident management & - & traffic flow & \\  & - & Equipment status monitoring (structural & - & Lower downtime and enhanced safety & \\  & - & health, loads, etc.) & - & Quick response to incidents and & \\ Management & - & Data-driven decision-making for & - & dynamic changes in urban & \\  & improved resilience and & & environments & \\  & emergency response & & & \\ \hline Maintenance and & - & High-fidelity simulations (e.g., AC and & - & Reduced unexpected failures and costs & \\  & wheel wear) & - & Extended service life of assets & \\  & - & Socio-technical rail DT & - & Improved safety through timely upkeep & \\  & Upgrade & - & Integration of advanced SHM and NDT & - & Real-time condition assessment and & \\  & & methods to identify potential & - & targeted interventions & \\  & & structural defects & - & Minimal impact on surrounding traffic & \\ \hline Decommissioning & - & 3D dynamic displacement measurement & - & Minimal impact on surrounding traffic & \\  & (no targets) & - & Lower environmental footprint via & [97; 98; 99; 100] \\ and Replacement & - & Deep learning for damage detection & - & Optimized design of replacement assets & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Digital twin (DT) technology across the transportation infrastructure lifecycle.  
efficient operations and maintenance management. DTs in areas regarding urban planning, traffic management, and infrastructure maintenance are currently being implemented. In this section, the applications will be explored through case studies that show the impact of transport systems.