V2I

V2I, or vehicle-to-infrastructure, is a subset of vehicle-to-everything (V2X) communications that enables data exchange between vehicles and fixed infrastructure such as traffic signals, road sensors, toll plazas, and variable message signs. The aim is to improve safety, traffic efficiency, and mobility by delivering real-time information and coordinated control between the road network and approaching vehicles.

V2I can use wireless technologies including dedicated short-range communications (DSRC) based on IEEE 802.11p and cellular V2X (C-V2X) based on 3GPP standards. Roadside units collect data from sensors and broadcast guidance, warnings, or timing information to nearby vehicles. Standardized message sets, such as SAE J2735 for data content and J2945 for privacy and security, help ensure interoperability; Europe uses compatible ITS-G5 systems.

Typical applications include adaptive signal timing and signal phase information at intersections, red-light and speed advisory warnings, dynamic lane management, tolling and price information, and hazard or incident alerts. V2I can enable green waves by coordinating traffic signals with vehicle movements, reducing stops and improving travel times while supporting emergency vehicle priority in some deployments.

Architectures combine vehicles, roadside units, backhaul networks, and edge or cloud computing for data processing and decision making. Latency, reliability, and security are critical due to safety-related use cases. Challenges include cross-technology and cross-border interoperability, spectrum policy, cybersecurity, privacy protection, and the high upfront costs of deploying dense infrastructure. Pilot programs and standards work continue to address these barriers.