It is very important that engineers not underestimate the contribution that delay time can make to total evacuation time. Studies of evacuation drills in apartment buildings have shown that, on average, travel time makes up less than 25 percent of the average total time to evacuate.’ In office evacuations, however, delay times can be extremely short, and the largest proportion of total evacuation time is accounted for by travel time. Therefore, the selection, estimation, or calculation of premovement times is extremely important to obtain valid results.