ABSTRACT
Road traffic is defined as movement of road vehicles, bicycles and pedestrians. The most important features of the traffic is effective and safe transportation of passengers and goods. Traffic takes place in complex system consisting of road infrastructure, vehicle operators, vehicles and weather conditions. Each of these factors is complex and undergoes systematic and random changes. Safety is provided in that system by the means of safety in soft (law, regulations, and local rules) and hard form (traffic signals, barriers, etc.). In this light an accident is a fact of violation of certain safety condition. In the idea of MORT (Wixon 1992) it might be understood as releasing some energy stored in transportation system.
