Case I: different evacuation processes of a single trial with different pedestrian densities: (a1)–(a4) high pedestrian density where the initial number of pedestrian is 800 and (b1)–(b4) low pedestrian density where the initial number of pedestrian is 300 at different time steps: (a1) and (b1) step = 0, (a2) and (b2) step = 200, (a3) and (b3) step = 400, and (a4) and (b4) step = 600. Here, P_in donates the number of pedestrians left in the waiting hall and P_out donates the number of pedestrians who have escaped from the waiting hall at the specific time step.