Link Type: Field to Field

Roadside Equipment --> ITS Roadway Equipment:
signal priority service request


signal priority service request (Information Flow): A service request for vehicle priority issued to a traffic signal controller that results in green extension or other accommodation for the priority vehicle, within the current signal timing plan. The request includes the priority level, the desired time and duration of service, and the intended travel path through the intersection. This flow also allows the RSE to cancel a previously issued request for priority.

Roadside Equipment (Source Physical Object): 'Roadside Equipment' (RSE) represents the Connected Vehicle roadside devices that are used to send messages to, and receive messages from, nearby vehicles using Dedicated Short Range Communications (DSRC) or other alternative wireless communications technologies. Communications with adjacent field equipment and back office centers that monitor and control the RSE are also supported. This device operates from a fixed position and may be permanently deployed or a portable device that is located temporarily in the vicinity of a traffic incident, road construction, or a special event. It includes a processor, data storage, and communications capabilities that support secure communications with passing vehicles, other field equipment, and centers.

ITS Roadway Equipment (Destination Physical Object): 'ITS Roadway Equipment' represents the ITS equipment that is distributed on and along the roadway that monitors and controls traffic and monitors and manages the roadway itself. In CVRIA, this physical object represents all of the other ITS field equipment that interfaces with and supports the Connected Vehicle Roadside Equipment (RSE). This physical object includes traffic detectors, environmental sensors, traffic signals, highway advisory radios, dynamic message signs, CCTV cameras and video image processing systems, grade crossing warning systems, and ramp metering systems. Lane management systems and barrier systems that control access to transportation infrastructure such as roadways, bridges and tunnels are also included. This object also provides environmental monitoring including sensors that measure road conditions, surface weather, and vehicle emissions. Work zone systems including work zone surveillance, traffic control, driver warning, and work crew safety systems are also included.

Included In

This Information Flow is in the following Applications:

This Information Flow is in the following Application Objects:

Communication Diagrams

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This profile describes standards applicable to communications between roadside equipment and other field equipment such as traffic signal controllers that is represented by ITS Roadway Equipment in CVRIA.



Characteristic Value
Time Context Recent
Spatial Context Adjacent
Acknowledgement False
Cardinality Unicast
Initiator Source


This information flow triple is in the following applications with the following security levels.

Information Flow Security
Application Confidentiality Integrity Availability
Basis Basis Basis
Transit Signal Priority Not Applicable Moderate Low
There is no sensitive or confidential information within this messages. Additionally, it could be inferred by observing either the presence of a transit vehicle near an intersection, or the effect on the timing of the intersection. This is also transmitted as a result of broadcast data. The RSE is transmitting a request to the ITS RE on behalf of a transit vehicle. It should only be making requests on behalf of an approved vehicle. A corrupted request may lead to a transit vehicle not receiving a green light after requesting it. In this case, this may lead to traffic delays. If an unapproved vehicle is able to forge these requests, they may cause larger scale traffic delays. If the ITS RE does not receive any requests, the vehicle may not receive the priority it requested. In the worst case scenario the transit vehicle would be forced to wait at some lights until they turned green. It would be more useful for a device to support this application, and only have some messages received, than to not support this application at all.