Since man is becoming a very dangerous polluter in the world day by day, the preservence of the natural resources is getting more important. The sustainable development concept is the key to mention the start points of action in order to protect the environment we live in. For a sustainable development in urban areas, the improvements in the transportation sector has to be examined and controlled precisely. While the transportation sector is supporting the economic growth it has negative impacts on the environment. In this paper, the relationships between the transportation sector and economic growth and environment are analysed. By using the data representing the current urban transportation systems' shares in Istanbul, the impacts of the road transportation modes on environment and scenarios developed for 2010, are presented. Finally, possible measures to decrease the negative impacts of the urban transportation in cities and in Istanbul are discussed.