The main objective of this research is to include stochasticity and randomness inherent to the operation of a bus transport system as well as the interaction between buses on the capacity calculation process. Congestion on platforms, poor condition of the pavement and interaction between vehicles can affect the operation of buses. Deterministic formulas are not able to include such phenomena on the capacity estimation. For the development of this research, 3 VISSIM models were built and calibrated in order to calculate the capacity of 3 different locations on a BRT system. The research outcomes show how the use of formulas and deterministic conditions can yield very different results of the capacity of a transport system compared to micro-simulation model results. This confirms the need of stochastic elements during the capacity estimation of a BRT system.