Development of traffic systems has led to increased costs of traffic which should be further reflected in increased traffic safety, environmental protection, less air pollution, increased quality of life for people in the cities, and general reduction of external costs caused by traffic. The necessity of protecting the environment from the pollution caused by traffic imposes stringent ecological standards which has to be respected, as well as monitoring the existing ones. The problem of the transition countries is to find an optimal approach in imposed ecological standards, necessary investments and maintenance of existing traffic systems. There is no uniform model of the strategy of sustainable development of traffic systems that would protect the environment, health and quality of people's lives or respect all legal norms and regulations. Therefore, there is a requirement to define factors that would be applicable to all transport systems from an ecological point of view. Analyzing key factors of traffic systems of road, rail and water transport that have environmental effects and through which it would be possible to influence the external costs of transport, to conduct further research and determine the basic parameters which would limit the strategy of sustainable development of transport systems were perceived.
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