TrafficAuth is powered by OmniTrust (formerly INTEGRITY Security Services)
TrafficAuth is powered by OmniTrust (formerly INTEGRITY Security Services)
TrafficAuth enables DOTs to modernize signal priority and preemption with secure, standards-based V2X communication—allowing authorized vehicles to request priority at connected intersections with multi-vendor interoperability, certificate-based trust, and fine-grained permission control.
Signal priority and preemption are among the most valuable connected transportation use cases for DOTs and city operators.
Transit vehicles need more predictable travel times. Emergency vehicles need faster, safer passage through intersections. Maintenance fleets may need temporary priority during storms or infrastructure events. Freight and logistics operators may benefit from managed movement through congested corridors.
Many legacy systems already support some form of signal priority or preemption. These systems often work well in specific deployments, but they are typically limited by proprietary technology, vendor-specific integrations, and incomplete security models.
V2X changes that.
The V2X approach provides a standardized, interoperable, and secure method for authorized vehicles to request priority or preemption at connected intersections. It enables DOTs to move from isolated, vendor-specific systems toward a common trust model that can support multiple vehicle classes, multiple equipment vendors, and multiple operating regions.
Traffic signal priority and preemption can improve safety, reduce response times, and support more efficient roadway operations. But these capabilities also affect the entire intersection environment.
Granting a request may change signal timing, alter traffic flow, affect pedestrians and cyclists, interrupt transit coordination, or impact adjacent intersections. That means DOTs need more than a way to receive a request. They need a way to decide whether the request is authentic, whether the sender is authorized, and whether the request should be granted under current conditions.
Common DOT questions include:
Legacy systems often answer these questions only within a narrow deployment. V2X provides a standards-based way to answer them across a broader ecosystem.
Traditional priority and preemption systems may rely on optical emitters, proprietary radios, GPS-based fleet systems, cellular applications, or vendor-specific intersection equipment. These systems can be useful, but they often create operational silos. The V2X method is different because it is built around open standards for message exchange, security, and interoperability.
With V2X, authorized vehicles can send standardized Signal Request Messages, or SRMs, to V2X-enabled intersections. Intersections can respond using standardized Signal Status Messages, or SSMs.
The same basic message framework can be implemented by different vendors, enabling a more open and interoperable deployment model.
The TrafficAuth ecosystem is already aligned with standards-based V2X communication, including Direct V2X, Network V2X, SAE J2735 message concepts, and IEEE 1609.2 security. Existing TrafficAuth materials describe SRM and SSM as part of the V2X message environment, including network-based topic support for signal request and signal status messages.
1. An Authorized Vehicle Approaches
An emergency vehicle, transit vehicle, maintenance vehicle, freight vehicle, or other authorized participant approaches a V2X-enabled intersection.
The vehicle is equipped with V2X capabilities and valid security credentials that identify it as part of a trusted ecosystem.
2. The Vehicle Sends a Secure SRM
The vehicle sends a digitally signed Signal Request Message to the intersection.
The SRM may indicate the type of request, the vehicle’s role, its approach, its movement through the intersection, and other information needed to evaluate the request.
3. The Intersection Validates the Sender
The intersection infrastructure validates the message security. It checks whether the message is authentic, whether it has been altered, and whether the sender has valid credentials.
This is where V2X security becomes essential. The intersection is not simply receiving a request; it is receiving a request that can be cryptographically verified.
4. The Intersection Evaluates Permissions and Conditions
After validation, the intersection evaluates whether the request should be granted.
That decision can consider:
5. The Intersection Responds
The intersection may grant, deny, queue, modify, or otherwise manage the request based on agency policy and real-time conditions.
This response can be communicated using a Signal Status Message, allowing the requesting vehicle to understand how the request is being handled.
Priority and preemption require careful governance. A transit bus, fire engine, ambulance, snowplow, utility repair truck, and freight vehicle may all have legitimate reasons to request favorable signal treatment — but not with the same level of urgency or authority.
V2X infrastructure supports advanced Service Specific Permissions, or SSPs, that allow special capabilities to be enabled only for selected, authorized vehicles.
This gives DOTs a way to define which vehicles are permitted to request specific signal services. For example, one class of vehicle may be allowed to request transit priority, while another may be authorized for emergency preemption. A third group may be allowed to request priority only under specific operating conditions.
This is a major advantage over less flexible systems that treat all equipped vehicles the same or rely on proprietary permission models.
The V2X ecosystem can also support Operator Organization IDs, or OpOrgIDs, which provide more detailed information about the organization or operator associated with a request.
This can help DOTs distinguish between different requestors, such as:
This level of detail allows DOTs to apply more precise policies. A city may grant preemption to its own fire department, priority to a regional transit agency, and conditional access to neighboring emergency services. A state DOT may define different rules for state-owned vehicles, municipal vehicles, mutual-aid responders, and private fleet operators.
The result is a richer and more secure operating model for signal priority and preemption.
Transportation networks must be flexible during emergencies. A hurricane, wildfire, flood, snowstorm, major crash, utility outage, or regional evacuation may require support from vehicles that are not normally part of the local priority or preemption program.
With a standards-based V2X trust model, DOTs can temporarily alter permissions for specific vehicle classes, operators, or regions.
For example, during a weather emergency, a DOT could authorize:
When the event ends, those temporary permissions can be removed.
This gives DOTs a practical way to support emergency response without permanently expanding priority or preemption access beyond normal policy.
Signal priority and preemption can be supported through both Direct V2X and Network V2X models.
With Direct V2X, the vehicle communicates locally with roadside infrastructure using low-latency wireless communication. This is valuable for time-sensitive intersection use cases where local broadcast and rapid response are important.
With Network V2X, authorized systems can exchange V2X messages through cellular and cloud-based infrastructure.
This can accelerate deployment, allow more vehicle types to participate, and support fleet or agency systems that may not yet include dedicated onboard radio equipment.
The strongest deployment model is often hybrid. Direct V2X can support proven local intersection communication, while Network V2X can extend participation to more vehicles, fleets, applications, and operational systems.
TrafficAuth helps DOTs build the trust foundation needed for secure signal priority and preemption.
TrafficAuth-SCMS supports certificate-based trust for V2X devices and vehicles, helping agencies determine which participants are authorized to send secure messages and request special services.
TrafficAuth-Portal gives operators visibility into their connected device environment, supporting monitoring, diagnostics, and operational management across the deployment lifecycle.
National Mobility Interchange, where applicable, can support Network V2X message distribution, helping agencies extend V2X participation beyond direct radio-equipped systems.
Together, these capabilities help DOTs move toward a secure, interoperable signal priority and preemption model that can scale across vendors, fleets, corridors, and jurisdictions.
Signal priority and preemption can improve emergency response, transit reliability, roadway operations, and public safety. But these capabilities must be governed carefully.
DOTs need to know who is asking, what they are asking for, whether they are authorized, and whether the request should be granted under current conditions.
V2X provides the standardized, secure, multi-vendor framework needed to make that possible.
With TrafficAuth, DOTs can build signal priority and preemption systems around trusted devices, authenticated messages, flexible permissions, and operational visibility — creating a safer and more interoperable foundation for connected intersections.
