(eng): The transition between low and high density phases is a typical feature of systems with social interactions.This contribution focuses on simple evacuation design of one room with one entrance and one exit; four passing-through experiments were rganized and evaluated by means of automatic image processing.The phase of the system, determined by travel time and occupancy, is evaluated with respect to the inflow, a controlled boundary condition. Critical values of inflow and outflow were described with respect to the transition from low density to congested state. Moreover, microscopic analysis of travel time is provided.