SignalPhase and Timing (SPAT) is a signal from traffic engineering. SPAT messages are used in car-to-car communication and are used as real-time information by traffic control systems, such as a traffic light. SPAT messages thus contribute to improving traffic flow.
In C2C communication, the SPAT signal is transmitted by roadside units( RSU) to the vehicles passing the infrastructure component. Such a SPAT signal, together with a Geometric Intersection Description( GID), can inform a motorist about the condition of a roadside intersection.