Recently there have been major fires in a number of European tunnels that required reevaluation of road tunnel fire loads. This showed that tunnel safety requires applying a fixed fire suppression system in addition to a tunnel ventilation system. This introduces a new challenge when designing tunnel safety systems. The type of ventilation system influences the type of sprinkler system and the sprinkler system design impacts the ventilation system performance. The design is also affected by the sequence of system activation. For example, sprinkler activation during calm airflow will differ from activation during fully developed turbulent air flow, which may carry away sprinkler droplets. On the other hand, the ventilation system may experience significant resistance due to water curtains created by the sprinklers. This paper addresses the types of tunnel ventilation systems, types of sprinkler systems, their influences and new design challenges to achieve a final goal, which is a safe tenable environment for evacuation during a fire emergency.