Sensor technologies(Infra-red sensing/Video and Camera Image Perception/RADAR/gyro sensor/inertial sensor), process data through mathematical algorithms to come up with a virtual understanding of the vehicle environment
In-vehicle digital maps and positioning technologies(GPS/WiFi/WiMax) as sensing systems to accurately identify the vehicle position and interpret the environment
If there is a gridlock/high traffic density detected by a roadside infrastructure then the roadside system can broadcast the information to all its nodes/vehicles
In turn using the DTN capabilities of VANETs, the information can be trasmitted to other vehicles heading towards this junction.
Likewise, it can convey to the incoming vehicles other paths, depending on a centralized system co-ordination of finding non-traffic routes at that point of time.