Fire accidents in road tunnels can form a great danger in the life of people if the evacuation process does not happen effectively. This paper introduces a numerical investigation of fire and evacuation analysis in a road tunnel and provides important insights into the conditions that people are exposed to during evacuation. The fire was assumed to originate from a bus with a fire size of 30 MW at the moment corresponding to the peak heat release rate. Results including smoke distribution, visibility distribution, paths of people during evacuation, people existence density, and people speed are presented and analyzed. One of the important findings of this paper is the estimation of the time available for people to evacuate safely before the approach of the smoke layer to the occupation zone causing deterioration of the visibility values. The discussion introduced a clarification of the connection between the time of exposure to smoke, people speed, and smoke propagation speed. Results showed that the time of exposure to smoke during evacuation can be significantly increased if the fire size is increased especially for persons located within 15 m from the fire location and take more than 2 min to take the decision of evacuation.