Security Lane Capacity at Peak
You are the terminal operations supervisor at an airport preparing the morning security plan. Four screening lanes are physically available. Each lane can process 180 passengers per hour when staffed with four screeners, and no lane can run with fewer than four. You have 12 screeners on the shift. Each screener may work a maximum of two hours continuously before a 30-minute break, and breaks cannot be skipped. The passenger forecast is 620 for 06:00-07:00, 700 for 07:00-08:00 and 560 for 08:00-09:00. Passengers who arrive after 07:40 must be processed within 15 minutes to make their flights, and the target average queue wait is under 10 minutes. At 06:00 two lanes are open and the queue is already 180 passengers. The airport has no automated tray-return system, so a lane cannot be reopened quickly once closed.
1. Calculate the maximum sustainable throughput and identify the bottleneck for the 07:00-08:00 peak.
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The staffing constraint binds before the lane constraint. Twelve screeners divided by four per lane gives a maximum of three staffed lanes, so the fourth lane is unusable regardless of demand. Three lanes at 180 passengers per hour give 540 passengers per hour. The forecast for 07:00-08:00 is 700, so the shortfall is 160 passengers in that hour, or about 23 per cent of demand. The bottleneck is therefore screener headcount, not lane hardware or tray return. A second constraint appears when breaks are applied: with all 12 screeners committed to three lanes, there is no spare person to relieve a lane for a 30-minute break. If one lane closes for a break, capacity falls to 360 per hour, making the shortfall much worse. The plan must therefore either add at least four screeners to reach 16 and four lanes, or accept a queue build and manage flights, but it cannot honestly claim to meet 700 per hour with the current roster.
2. Propose a lane-opening and break plan for 06:00-09:00 that respects the two-hour rule.
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Start from the lower demand and create a break buffer before the peak. At 06:00 open two lanes with eight screeners and keep four screeners as relief. From 06:00 to 07:00 the two lanes can handle 360 passengers against 620 forecast, so the queue will grow; use the relief staff to rotate breaks for the first group so that no one reaches two hours unbroken. At 07:00 open the third lane using the four relief screeners, giving 540 per hour. This is still below 700, so request four additional screeners from the duty manager before 06:30; if they arrive, open the fourth lane at 07:00. Between 07:00 and 08:00 rotate the first two-hour group off in 30-minute slots, replacing them with screeners who have already had a break. After 08:00 demand falls to 560, so keep three lanes open and begin releasing staff in break order. The principle is to bank breaks before the peak rather than during it, and to treat the relief pool as the mechanism that makes the two-hour rule survivable.
3. What residual risk remains in your plan, and what would you monitor or escalate?
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The residual risk is that the 07:00-08:00 shortfall is structural, not managerial: 540 capacity against 700 demand means at least 160 passengers will be handled after the hour, and the queue inherited from 06:00 is already 180. That queue threatens the 15-minute rule for passengers arriving after 07:40, particularly those on the earliest departures. Monitor queue length at five-minute intervals, the time of the oldest passenger in the queue, and the number of passengers called forward for boarding. Escalate to the duty manager and to airlines if the oldest-wait time exceeds 10 minutes before 07:30, so that late passengers can be prioritised by departure time rather than arrival time. Also monitor lane downtime: with no spare staff, a single equipment fault will remove 180 per hour of capacity. Keep a written record of the shortfall and the escalation, because the plan depends on a staffing decision outside the supervisor's control.