Green Priority (GP) aims to change the traffic signals status in the path of an emergency or high priority vehicle (e.g., public transportation vehicles), halting conflicting traffic and allowing the vehicle right-of-way, to help reduce response times and enhance traffic safety. This service is also known as “Traffic signal priority request by designated vehicles” or “Priority Request”. Different levels of priority can be applied, e.g. extension or termination of current phase to switch to the required phase. The appropriate level of green priority depends on vehicle characteristics, such as type (e.g. HGV or emergency vehicle) or status (e.g., public transport vehicle on-time or behind schedule). The vehicles request priority for an intersection, and the traffic light controller determines in what way it can and will respond the request.

This service architecture is largely based on the ARC-IT service package Transit Signal Priority, with customizations to support local user needs.