Adequate air conditioning and proper ventilation along with presumed fire fighting equipments are of great importance in case of underground subways. Heat generation along a subway track is a result of transitory and permanent heat sources. Taking both type of sources into account, the generated heat, the proportional required ventilation air fluxes and their respective pressure drops are calculated. Considering these fluxes and their relative pressure losses, a 3-D Finite-Volume, Full Navier-Stokes CFD code is used to simulate the geometry of the station with connecting half tunnels. The standard k-�model is used to take turbulence effects into consideration. Results of the CFD simulations are then applied to the calculations in order to increase the accuracy of assumptions. The results certify that designed ventilation systems are capable of keeping temperature and pressure gradients as well as local air velocities inside each tunnel and station in the standard comfort zone for passengers.