The dissertation discusses the possible operating scenarios of a longitudinal ventilation system in the conditions of road tunnel fire accidents with the aim of increasing the safety and security of passengers; fire brigades and rescue teams; as well as maintaining the integrity of the tunnel itself. Special attention is paid to aerodynamic phenomena of smoke distribution and propagation inside the tunnel in order to define the best suitable smoke propagation forms which create optimum conditions for activities characteristic of a particular fire phase (e.g. evacuation of passengers; fire-fighting etc). A synthesis of the data and knowledge generated by a number of fire tests and on-site testing of the tunnels recently constructed in Croatia; combined with the state-of-the-art scientific achievements in this field; and with the results of smoke propagation modelled by modern CFD tool; has led to the creation of a comprehensive operational strategy for the longitudinal ventilation system in the event of a fire. The strategy is presented in the form of “generic algorithms” whose internal structure is completely independent of the operational possibilities of a longitudinal ventilation system and of the geometric and civil engineering characteristics of the particular tunnel. The dissertation also presents the main features of mathematical and regulation models of ventilation system operation; which are the main part of the software for longitudinal velocity control; currently in the final phase of development. The software is expected to control the longitudinal ventilation system in automatic sequences of operation; both in normal operating conditions and especially during fire accidents.