In the field test, a consortium of carmakers, electronics suppliers, research institutes and the road traffic administration of the German state of Hesse jointly developed a number of use cases, protocols and interfaces for the communication among vehicles as well as between infrastructure elements (roadside units) and vehicles.
The use cases, developed by the Munich Technical University, included a cross traffic warning, emergency vehicle warning and a traffic sign assistant as well as automatic local warnings of obstacles, bad road conditions (for instance aquaplaning, black ice, or fog). Many hazardous and accident-prone situations could be defused.
The technology enables drivers to establish a more proactive and foresighted driving style. The assistant systems based on car2x technology issue a warning well ahead of intersections if another vehicle is approaching this intersection. Based on the trial data, the researchers estimate that more than 50% of all intersection accidents could be avoided if all vehicles were equipped with car2x capabilities.
The communications are based primarily on modified WiFi technology. In addition, every vehicle in the trial was equipped with internal sensors that enabled it to recognise potentially hazardous situations such as traffic stalls, slippery road conditions and more. By means of its ITS Vehicle Station (IVS) , the vehicle passes these data on to other vehicles as well as to the ITS Roadside Stations (IRS). If a hazardous signal is detected or received from outside, the vehicle electronics issues a visual and acoustic warning to its driver. The system can also be used to transport additional messages. For instance, in a parking garage, the cars can exchange information on free spots.
In its role as ITS Central Station (ICS), the simTD trial centre received the IRS data. In addition to the modified WiFi connections, the technology also uses mobile telecommunications services, in particular 3G services to relay Car2x messages.
If enough vehicles were equipped with car2x technology, the benefits could be enormous. The