SUMMARYEfficient management of public transportation systems is one of the most important requirements in rapidly urbanizing world. Forecasting the demand for transportation is critical in planning and scheduling efficient operations by transportation systems managers. In this paper, a time series forecasting framework based on Box-Jenkins method is developed for public transportation systems. We present a framework that is comprehensive, automated, accurate, and fast. Moreover, it is applicable to any time series forecasting problem regardless of the application sector. It substitutes the human judgment with a combination of statistical tests, simplifies the time-consuming model selection part with enumeration, and it applies a number of comprehensive tests to select an accurate model. We implemented all steps of the proposed framework in MATLAB as a comprehensive forecasting tool. We tested our model on real passenger traffic data from Istanbul Metro. The numerical tests show the proposed framework is very effective and gives higher accuracy than the other models that have been used in many studies in the literature.