2. The travelling speed of an escalator and the number of flat steps provided at landing determines the time available for passengers to adjust their feet positions to avoid being tripped over. For an escalator moving at 0.5 m/s and with two flat steps each of 380mm tread (step depth), the available time is 380/500=0.76 to 2×380/500=1.52 seconds, depending on where the passenger has straddled two adjoining steps. The situations are elucidated in Figure 1 below.