Development of city transport systems according to environmental sustainability approach is offered in the article. City transport system sustainable development is a part of global sustainability. The global sustainability, in turn, includes the satisfaction of human needs without compromising the ability of future generations to meet their needs in the future. Current research will help to promote more sustainable city transport system patterns. The analysis of chain of causality, between the city transport system and the impacts on the environment, is described in details. The chain of causalities - from source to destination will be discussed. It is significant to understand what an environmentally sustainable city transport system is. An impacts and indicators, criteria and methods for the assessment - all this must be studied and developed for successful environmentally sustainable city transport system. The definition and formulation of sustainable city transport system indicators for different traffic conditions will be given in the article and monitoring possibilities will be described. Patterns of environmental sustainability of city transport systems will be offered in the article.