The technology, explained by people who deploy it

Vehicle-to-everything radio

V2X lets vehicles talk directly to each other (V2V), to roadside infrastructure (V2I), to pedestrians' devices (V2P) and to the network (V2N). In the United States this runs in the 5.9 GHz band. The first generation, DSRC, used IEEE 802.11p and IEEE 1609 and powered the national Safety Pilot and the early state pilots we helped build. The current generation, C-V2X, uses 3GPP cellular sidelink (PC5) and is the basis of the FCC's rules for the band and USDOT's deployment plan.

What did not change: the applications, the SAE J2735 messages, the security model and the need to monitor the roadside units that broadcast them. What did: radio hardware, interference considerations, and the need to test interoperability across vendors again.

Managing a fleet of roadside units

An RSU is a small Linux computer with a radio, a GNSS receiver and a network connection, mounted on a pole in the weather. Managing hundreds of them requires standard objects (NTCIP 1218 over SNMPv3), a monitoring platform that polls them, dependency logic that understands the cellular gateway in front of each one, and processes for firmware, configuration and certificates.

The Security Credential Management System issues enrollment and authorization certificates to every device. Expired or missing certificates silently stop a unit from being trusted, so certificate state is one of the first things we monitor.

From connected to automated

Connected vehicles share information; automated vehicles act on it. SAE J3016 defines six levels of driving automation, from driver assistance to full automation. Roadside infrastructure supports both: SPaT and MAP enable eco-approach and signal cooperation, SDSMs extend a vehicle's perception around corners, and corridor sensing platforms feed digital twins and advisories.

Our principal designed USDOT's first CARMA cooperative automation fleet and the first fully automated speed-control prototype at the FHWA Saxton laboratory, and ITS Roads now engineers the roadside sensing cabinets for multi-state AI roadway programs.

Automation at the roadside

Beyond vehicles, the roadside itself is being automated: controllers that reconfigure signs, gates and lighting from sensor inputs; industrial I/O that replaces relay logic; telemetry that closes the loop with the operations center. We integrate controller- and PLC-class devices, sign protocols and sensors into systems that run without a technician on site.

USDOT's national V2X deployment plan

Published in 2024, the plan sets a path to nationwide, interoperable, cybersecure V2X on C-V2X. Its milestones give agencies and vendors a shared target and make RSU testing, monitoring and management a core operations function rather than a pilot activity.

• 2024 to 2028: V2X on 20% of the National Highway System; 25% of signalized intersections in the top 75 metros; 12 interoperable deployments
• 2029: 50% of the NHS; 50% of top-metro intersections; 25 interoperable deployments
• 2036: full NHS coverage; 85% of top-metro intersections; 50 interoperable deployments

What it means for an agency

Every new signal cabinet and corridor project is a candidate for an RSU. The agencies that will meet the milestones are the ones that can test units against the standard, monitor them at scale, keep certificates valid and prove with data that messages are reaching vehicles. That is the service line ITS Roads built for Colorado and offers nationwide.