In-car sensors and controllers input and analyse data such as vehicle speed, steering-wheel angle, tyre grip, windscreen-wiper activation and airbag triggering. The results of the analysis are indicative of traffic conditions and possibly hazardous situations such as ice, obstacles or accidents. Cars equipped with either 5G or Wi-Fi technology (ITS-G5) can send a warning message if a problem is detected (e.g. if they have broken down or have stopped suddenly and present a safety risk). In case of ITS-G5 technology, this is transmitted using a communication protocol via a Wi-Fi-like radio link that is specially engineered for use with moving vehicles and has a range of up to around 1,000 metres. Warning messages can be picked up either directly by other connected vehicles in the vicinity or by stationary communication units at the roadside, which in turn can send signals to vehicles and to a server that centralises information and updates it in real time.
For example, when a vehicle approaches an accident site it sends out a warning signal that is received by the cars behind it. These then relay the message to alert other vehicles, and so on. In addition, the warning signal can be picked up by a stationary unit in the vicinity of any of these cars, and this unit automatically notifies the central system, which will alert the emergency services accordingly. A similar procedure can be triggered for any number of potentially hazardous incidents such as animals on the road, temporary roadworks, traffic jams, landslides, etc. In time, it may even be possible for drivers to receive advance warning of motorcycles and tractors on the road.