Earlier this year we reported on a vehicle-to-vehicle communications system being developed by a consortium of European manufacturers, and now Toyota and Honda have joined the growing ranks of carmakers working on the future safety technology. The two carmakers have now announced plans to show off their own vehicle-to-vehicle communications systems in a few days at the World Congress on Intelligent Transportation Systems.

Honda's vehicle-to-vehicle communication demonstration, using an Acura RL sedan, has been designed to showcase the potential for inter-vehicle communications as a means to reduce vehicle collisions at intersections.

Through the use of autonomous sensors and vehicle-to-vehicle radio communication, the goal of the Honda system is to warn drivers of potential dangers at intersections in situations where the driver's view of the oncoming vehicle is obstructed by buildings, trees, fences or large trucks. In the event of an impending collision, the system can provide audio, visual and tactile alerts to the driver.

Similar to the Car-2-Car communications system being developed by Volkswagen and other European manufacturers, Honda's system will use a short range communications system at a frequency of 5.9 gigahertz (GHz). The system allows each vehicle to broadcast a "heartbeat" signal that includes key information such as speed, acceleration and brake status, which can be detected and interpreted by other vehicles in close proximity.

Toyota will also be showing off a similar system, with plans to reveal a "smart car" that also uses the 5.9 GHz frequency to create both car-to-car and car-to-infrastructure communications. Toyota's demonstrations will include pedestrian and vehicle collision avoidance sequences, as well as a traffic congestion monitoring system that informs a driver of the optimum speed at which to maintain a constant traffic flow by sequencing all green-light traffic signals.

Other similar systems in the works include versions by General Motors, Mazda, Ford, Nissan, Volvo, and BMW.