Alerting for vehicles demonstrating hazardous driving behavior

Cooperative Collision Warning Systems (CCWSs) have become a major vehicle safety application in intelligent transportation systems. Vehicles organized in a vehicular ad-hoc network use a CCWS communication protocol to propagate emergency messages about hazardous events. Police cars, ambulances responding to incidents and speeding cars or motorcycles that constantly vary their speed, change lanes or commit other apparent traffic violations are examples of vehicles that demonstrate hazardous traffic patterns. Using their GPS and motion sensors, vehicles can detect those traveling in nearby avenue sections who constitute a threat. In this paper, we propose a broadcasting protocol that alerts drivers about the presence of moving vehicles demonstrating hazardous driving behavior. In order to limit the volume of redundant transmissions, our approach selects the vehicles to be responsible for transmitting the emergency information for a hazardous vehicle. In this context, we provide mechanisms to create and maintain a chain of transmitters. This chain "covers" the road sections on which a hazardous vehicle is moving. Our protocol attempts to increase the probability that an endangered vehicle does obtain timely information about a hazardous vehicle and reduce the total communication traffic imposed in urban environments where the vehicles' density is often high. We experimentally evaluate our suggested protocol by comparing it with two alternative CCWS broadcasting approaches and we ascertain the extent in which the above objectives are met.