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66 Airport Passenger Terminal Planning and Design inspection, moving walkways or an automated people mover may be appropriate. Because the departing passengers use the same gates as international arrivals, control doors and monitoring of the corridor system is required to prevent mixing of arriving and departing passengers. See Section VI.3.10, Circulation, of the Guidebook for guidance on corridor sizes. CBP Primary Because all passengers are subject to CBP primary inspection, the capacity of primary inspec- tion generally dictates the overall capacity of the FIS. Under current guidelines, one double pri- mary inspection booth (two agents, also referred to as a "piggy back counter") is officially rated at an average of 100 passengers per hour. There are usually separate queues for U.S. citizens and foreign nationals, each of which will have a different average processing rate. CBP primary facilities are sized for a capacity stated in terms of passengers per hour. This capacity rating is "steady state," assuming a relatively well-distributed pattern of arriving flights. For such a rating to be correct, a design hour volume of 900 passengers, for example, would need to consist of six flights, arriving every 10 minutes, with 150 passengers each, rather than two flights of 450 passengers arriving within a few minutes of one another. Even in airports that have shorter-haul international flights, the idea that they will be of uniform size and evenly spaced is difficult to accept as a typical or reasonable planning standard. However, there are factors which "spread" or dilute the impact of arriving passengers, notably the distance between aircraft gate and the government inspection booths, combined with the metering of passengers out of aircraft and variations in the speed they walk. It should be noted that speeds are more divergent in terminals where moving walkways are provided. The number of booths required for primary facilities is typically prescribed by CBP based on the design hour passenger volume and, as such, consideration of dynamic issues will not usually impact that aspect of the facility. However, while agencies may specify minimum queue depth provision, they may not be sufficient depending on the likely distribution of design hour passengers amongst flights and the relative timing of those flights. Examining demand in a smaller time frame, 15 or 30 minutes, is often helpful in understanding the maximum length of queue to be accommodated. One other key area to consider in arrivals facilities is the impact of off-time (i.e., early or late) flights. In addition to a base analysis, if off-time data is available, a number of sensitivity tests should be performed to fully understand the dynamics of the facility. The spreadsheet model for primary inspection has a tool for illustrating how variable arrival times for the same number and size of flights can impact passenger arrival rates and queue sizes in the primary area. The FIS/CBP model is designed to estimate the passenger queue lengths, space requirements, and passenger delay time for primary processing; baggage claim requirements; and the time bag- gage claim devices will be in use. This model functions in the same manner as the other spread- sheet models with links to the Table of Contents and the User's Guide, and the use of color-coded cells as seen in Figure 80. The first section in this model is a random flight arrival time example that adjusts a group of five flights by as much as 15 minutes early or late and runs a mini-queue model on each of 10 iterations to determine (1) a range and average for the maximum number of queued pas- sengers and (2) the minimum, maximum, and average wait times in the primary processing queue. This model is separate from the preliminary data used later in this section and acts as a stand-alone example (see Figure 81) with a dedicated randomizing queue model. From this example, users can see the influence and possible effects that arrival variability can have on
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Federal Inspection Services/U.S. Customs and Border Protection Model 67 Figure 80. FIS/CBP model. primary processing, which would then have an impact on the use of baggage claim. Users can enter their own flight arrival times and aircraft seating capacities to test various flight arrival scenarios. In addition, the model allows users to vary aircraft passenger load factor, the num- ber of primary inspection booths, and the rate at which passengers disembark (unload) from the aircraft. Users can add five flights in the one-hour example window of 1,600 to 1,659, or less if they so desire. The queue model assigned to this bank of flights randomly adjusts the arrival time by up to 15 minutes early or late for each of the input flights. With the load factor and unload rate entered, the queue model will determine when and how fast the passengers disembark from the flights and proceed to primary processing. The last function of the queue model uses the number of staffed inspection booths and the processing rates that the user entered to esti- mate the average and maximum wait times likely to be experienced by the passengers. This is useful in studying the effects of possible understaffing by CBP. The maximum number of pas- sengers in the queue is also estimated and can be used to determine the size of the queue needed. A chart showing the passengers arriving at primary processing and how many passen- gers are in the queue, based on the original schedule and one of the random variations, is illus- trated in Figure 82. Each time the randomizer button is clicked a different random variation is generated and the chart will depict a new scenario. Figure 81. Example of random flight arrival time model.
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68 Airport Passenger Terminal Planning and Design Primary Processing (5 sample flights) 350 300 250 Passengers 200 150 100 50 0 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 Start Time Minutes Variable - Passengers in Queue On Time - Passengers in Queue Variable - Arriving Passengers On Time - Arriving Passengers Figure 82. Example of random flights and initial flights queuing chart. The example in Figure 81 gives a range of wait times that may be experienced by passengers in a scenario similar to the five-flight example period. The maximum wait time based on 10 iter- ations or runs in the queue model yielded a range of 17 to 34 minutes, and a maximum required queue depth of 44 feet. The minimum queue depth at any U.S. airport with international service is required to be at least 50 feet (75 feet normally); so, under the input conditions in this exam- ple the existing queue depth is satisfactory. The next section in this model allows the user to look at a single sample international flight arrival and run a queue model to estimate wait times and queue size requirements. The demand in this case will be the estimated seat configuration of a likely international flight of a desired aircraft. The user can specify the number of double booths to be used in passenger processing and at what rate. One hundred passengers/per hour/per double booth is the CBP standard and should be used unless there is better local data that supports using a different known process- ing rate. This value can also be varied to do a sensitivity check on the overall process. Among the many CBP facility requirements is the number of double inspection booths and the minimum passenger queue depth and width for primary inspection. This spreadsheet model allows the user to evaluate a CBP-recommended passenger flow rate and booth count, or user-selected values. Figure 83 shows the input section where the user makes these decisions. The process in the single-arrival example will follow the same methods used in the multi-flight example except there is no random variability. The user enters the number of seats, load factor, and unload rate to determine the demand on primary processing. After the user next enters the number of double booths and processing rate, the queue model will estimate the maximum wait time and maximum number of passengers in the queue. To see the effects that bucket size has on a queue model example, the user can select either a 1-minute or 5-minute bucket size to observe minor variances. As in the first example with multiple flights, the output from the queue model will also estimate the required queue depth based on the existing number of double booths and desired LOS area for the passengers. In Example #2, shown in Figure 83, the user's entries have determined that if 15 square feet per passenger is the desired LOS area/passenger then the queue depth would need to be at least 43 feet.
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Federal Inspection Services/U.S. Customs and Border Protection Model 69 Figure 83. Example of single arrival for primary processing. The standard double inspector booth is approximately 14 feet deep and, with the passenger standing areas on either side, 11 feet 6 inches wide. The CBP requires a 7-foot minimum distance from the booths to the holding line for waiting passengers. CBP recommends a 50-foot mini- mum queue depth for smaller airports, and a 75-foot queue depth for larger airports, but the actual depth should be a function of the peak number of passengers forecast to be in the queue and the LOS assumed. Separate queues are required for U.S. residents and for foreign citizens. Although Figure 84 shows equal queuing areas, the division of the queues would be determined by the nationality mix of the passengers. The width of the queue lines is recommended to be 5 feet as most international passengers are traveling with others. 11FT 6IN / 3.5M standard booth 12FT / 3.7M min. circulation 14FT / 4.3M standard double booth 7FT / 2.1M min. to waiting line 120FT / 36.6M 75FT / 22.9M min. queue area depth 12FT / 3.7M min. circulation Source: Hirsh Associates Figure 84. Primary inspection lanes with CBP standard dimensions.