Abstract: Safety is an important attribute of public transportation for both the operators and the passengers. For the operator accident will cause additional costs, lost time and out-of-service time. A safe public Transportation system may be a factor to encourage public use. Characteristics of public bus accidents in Tehran from 2000 to 2004 were identified. Analyses were conducted for determining accident characteristics of the major transportation system in Tehran. The united public bus company plays an important rule in the public transportation systems of Tehran; the condition of public transportation of this city will be assessed. Meanwhile the optimization research report of the public transportation system is programmed for Tehran transportation, which is described in this study. In this study, also we provide a model for prediction numbers of public bus accident in Tehran, in the future.