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As a result of the Aviation and Transportation Security Act (ATSA), all checked baggage is subject to screening for explosives. Depending on the size of the airport, available space, and budget, two types of systems may be deployed: â¢ The smallest airports have used ETD units, typically located in the check-in lobby as the pri- mary form of baggage screening. These are fully manual systems with the slowest throughput rate. Typically a single ETD unit shared by two screeners can process up to 66 bags/hour. ETD units also are used for checking oversized bags which cannot fit though EDS equipment, and for more detailed examination of bags alarmed by EDS units. â¢ EDS are capable of automatically detecting explosives and then providing a three-dimensional view of the bagâs contents to TSA screeners for further analysis. Most of the currently deployed EDS technology was developed prior to the passage of ATSA, based on standards set forth by Congress in the Aviation Security Improvement Act of 1990. After large-scale deployment of EDS in 2002 and 2003, equipment manufacturers have incrementally improved performance in terms of false alarm rates and throughput capabilities. In addition, new EDS equipment has been certified. Most of the currently deployed EDS machines operate with throughput rates between 100 and 550 bags/hour. EDS units have widely varying capacities and are configured in different ways: â¢ Stand-alone EDS are the simplest EDS installations, typically located either in the check-in lobby or immediately behind the ATO counter. Screeners manually load the bags into the EDS unit and then move the screened bags to a bag conveyor into the baggage make-up room. Typical throughput rates are in the range of 100 to 200 bags/hour. â¢ Mini in-line systems have a single (or possibly two) EDS units on a feed conveyor from the ATO counter to the make-up area. This configuration requires the least in the way of bag sortation. EDS units for these simple in-line systems typically have capacities of 100 to 400 bags/hour. â¢ Medium- and high-volume systems are highly integrated, highly automated, and low labor- intensive systems with multiple EDS units arranged in a screening matrix which requires sophisticated baggage sortation and tracking. Current EDS units for these systems have capac- ities of 400 bags/hour. Expected upgrades to these EDS units are estimated to increase through- put to the range of 500 to 700 bags/hour. Future EDS units in development are expected to have capacities of up to 1,000 bags/hour. Thus, the baggage handling systems supporting the EDS screening matrix should consider possible increases in EDS capacity during the life of the system. More detailed information can be found in the TSAâs Planning Guideline and Design Standards for Checked Baggage Inspection Systems (release date October 10, 2007. Planners should check for updates). The spreadsheet model for Baggage Screening is set up in the same manner as the other mod- els where there is a link back to the Table of Contents and the Userâs Guide and all the cells are color coded for consistency as seen in Figure 54. 43 Baggage Screening Model
Airports of varying sizes and traffic levels will require different screening systems. A full analysis methodology for sizing a checked baggage screening system is beyond the scope of this planning guide. However, an initial estimate of baggage volumes and EDS equipment can be made given certain basic assumptions and design hour passenger volumes. The spreadsheet model allows for preliminary estimates of the major equipment necessary for EDS system programming and follows the standard three-level TSA protocols for checked baggage inspection systems (CBIS). Figure 55 demonstrates the basic process used to estimate baggage screening requirements. The first step in the model is to determine bag load, which is driven by the design hour check- in passengers. Line 8 lets the user choose to use the flow of design hour passengers checking in from the Check-in model, or to select a different user-specified input. Lines 9 and 10 in the model will request information from the user in relation to bag checking preferences. This data along with the surge factor developed by TSA provides the system demand that will drive the estimates for equipment and space. The surge factor should be used, but the user can turn the application on and off in Line 13 to see the actual effect on the equivalent bag rate. The demand segment is titled Design Hour Bag Load in the model as illustrated in Figure 56. To segment the model inputs for the next section, the estimated percentage of over-/odd-sized bags is needed. This process assumes that most systems will be EDS for Level 1 screening; for smaller airports with only ETD systems, those selections are made in the next section. The preferred TSA screening protocol involves three different screening levels. Level 1 screening is performed with EDS units for all bags that can physically fit in an EDS. All bags that alarm at Level 1 are automatically subject to Level 2 screening. During Level 2 screening, TSA personnel view alarmed baggage images captured during the Level 1 EDS scan, and clear any bags whose status can be resolved visually. This process is referred to as on-screen resolution (OSR), which, for in-line systems, allows the continuous flow of bags through the system until a decision is made. All bags that cannot be resolved at Level 2, and all bags that cannot use EDS 44 Airport Passenger Terminal Planning and Design Figure 54. Example of Baggage Screening model. Area for Level 1 Inspection Level 3 ETD Units required for follow up inspections Design Hour Bags to Process Area for Level 2 Inspection Design Hour Passengers Level 1 EDS Units required to Process Outbound Bags TSA Baggage Screening Process Level 2 OSR Operators required to review scans of Alarmed Bags Area for Level 3 Inspection Figure 55. Baggage Screening process flow diagram.
for Level 1 because of size restrictions, are sent to Level 3. Level 3 screening is performed man- ually and involves opening the bag and using ETD technology. The small percentage of bags that do not pass Level 3 screening are either resolved or disposed of by a local law enforcement officer. The model follows this three-step procedure and estimates the equipment quantities for either ETD or EDS or both. The user selects the existing or desired system parameters, and inputs the estimated process rates from records or using TSA suggestions. The outputs from the model are the number of EDS and ETD units required. See Figure 57. After determining an estimate for unit quantities, the last section of the model, as shown in Figure 58, estimates the space necessary in the lobby or back-of-wall screening area for the units and personnel to operate and function efficiently. These area calculations do not include the full baggage conveyor or sortation systems that may be required but are provided to give an indica- tion of the minimum areas necessary for the TSA screening process. Baggage Screening Model 45 Figure 58. Example of baggage screening space requirements. Figure 56. Example of Design Hour Bag Load model. Figure 57. Example of EDS/ETD equipment requirement screen.