摘要：Although the discussion on urban mobility involves the mass transportation modalities, most cities still trust on bus fleets. This research aims to present a model that proposes to identify the moment that may be made the option to sell or buy a used vehicle from the fleet of buses of urban public transport system, through the application of Real Options Theory (TOR). Research indicates that when the vehicle is new maintenance costs are low, basically covering the routine reviews and component replacement, but after a certain age, these costs grow. In this sense a question that always arises is to decide the appropriate time to acquire or dispose of a used vehicle. The theory used in this study, TOR, focuses on the Binomial Model in Discrete Time. Methodologically, the study was carried out with real data of a particular case of the bus fleet that served as support for the construction and testing of the proposed model and relied on data from a traditional bus company of the Espirito Santo state. The proposed model is validated through a numerical example that identifies the time for decision making. In the case study, the model showed the time of the option as of the end of the second year of use of the bus. The methodology and the results awaken to the need for managers to have information resulting data fleets and can make safe decisions, especially the "ideal" time for fleet replacement. For the government, this kind of studies can generate data drafting normative regulatory agencies in order to meet the dealers and public-private partnerships
