Digital Twins (DTs) are reshaping Intelligent Transportation and Communication Systems (ITCS) by providing continuously synchronized, executable models of vehicles, infrastructure, and communication networks. This survey offers a unified taxonomy and explicitly defines six DT categories from design perspective: Single-Vehicle DT (SV-DT), a per-vehicle twin that mirrors dynamics, perception, planning, and control for inner-loop analysis of the vehicle; Connected Vehicle DT (CV-DT), a fleet or multi-vehicle twin that coordinates interactions, cooperation, and resource sharing under communications; Environment DT (ENV-DT), a twin of roads, intersections, signals, and demand that supports monitoring, forecasting, and policy evaluation at corridor and system scales; Network DT (NET-DT), a communication twin that emulates V2X and backhaul state to assess latency, reliability, and capacity and to guide roadside unit placement; Safety and Security DT (SAFE-DT), a cross-cutting twin for hazard analysis, incident detection, robustness, and cyber resilience; and finally, Twin of Twins (ToT), an orchestration layer that composes heterogeneous twins to deliver system-level services with consistency. This survey formalizes a comprehensive modular DT architecture in ITCS, including data paths, modeling fidelity, and system synchronization, and distinguishes DTs from simulators and digital shadows. Open challenges are also discussed along with future directions, with the goal of developing efficient and sustainable next-generation intelligent vehicular network systems.
Zhang et al. (Fri,) studied this question.