Hi B747-436,
Do you not remember the Surface Movement Radar when I showed you round? We can still see aircraft movements under Low Visibility Procedures - the inbounds even have labels attached (until they vacate the runway), but a more robust system is being developed, eventually to be based around mode S transponders. Inbound, an aircraft cannot be cleared to land until the preceding has cleared the Localiser Sensitive Area (137m either side of the centreline). This is displayed on the SMR and with coded centreline lights on the field. Departing traffic (localiser guided takeoff), cannot be cleared for takeoff until the preceding has crossed over the localiser aerial. No conditional lineups are allowed. Only one pushback allowed in each cul-de-sac. All of these issues slow down the throughput of traffic. Not too many human factors as such, apart from the unfamiliar way of working and relying heavily on the SMR. Hope this helps.