Fire incidents occur in the tunnels of various countries of the world. Depending on the tunnel geometry, traffic structure, and fire defense equipment, a large fire may cause people to die and cause damage to the tunnel
structure. Threshold values for heat and toxic gas emissions that people would be exposed to a fire are defined in standards. To examine the change of the heat flux values that are defined in the standards with the heat release rate of the fire and the viability of the tenable environment during an evacuation in a tunnel fire, a model was created by reducing the dimensions of a tunnel by 1/12. Experimental studies and numerical studies carried out with the model in order to determine the instant that evacuation operation will start to impede and hazardous conditions dominate the fire scene and it is observed that results of both studies are in harmony.