Applicability of Portable Explosive Detection Devices in Transit Environments (2004)

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24 CHAPTER 4 CONCLUSIONS AND RECOMMENDATIONS 4.1 GENERAL OBSERVATIONS The results of the field testing of the portable EDDs are summarized below: The trace detection equipment was oper- ated under a wide range of conditions and performed well in the environment in which it was operated. It was proven reli- able in detecting trace explosives. However, due to the sam- ple collection method, it may not meet all the needs of the transit security force. Transportability. The units are lightweight and very trans- portable. During this study they were carried from station to station and set up, on average, eight times a day. Operator fatigue in carrying the approximately 21 pounds of equipment (Detector, cord, battery, and wipes) was not noted. However, a soft-side carry case to hold the detector and accessories is recommended for field use. Reliability of the Units. The portable EDDs tested in this study proved to be reliable. They had no systematic failures and were able to operate for extended periods. During this study, the instruments were operated in the field for a total of 140 hours over a 17-day period. In 1,600 individual tests, conducted under a wide range of conditions, no failures were noted. One concern with portable instrumentation operating in the field is battery lifetime and the need to carry spares. How- ever, in this study, all test sites had AC power available in the operating environment. The common availability of AC power allowed the operators to run the equipment on local power and charge the battery throughout the day. About one-third of the test was conducted outdoors, where the operators never had to suspend operations to change or recharge batteries because of the common availability of AC power throughout the operating environment. Extension of battery lifetime is not necessary, and the operators did not require spares in the field. The units operated reliably under the ambient conditions test, both indoors and outdoors. The temperature ranges under the ambient conditions varied from a low of 16° C/60° F to a high of 32° C/89° F. The relative humidity ranged from 24% to 73%. It is necessary to swab a virtually dry surface; there- fore, using the device in inclement conditions may not be rec- ommended, and rainy weather may cause times of non-use. Start-Up Time. Start-up of the unit usually took 10 to 15 minutes, although there were 5 days out of 17 (29%) that it took an extra 15 minutes to clear NO3 alarms that occurred on start-up. Throughput. On average, it took the test team 14 minutes (840 seconds) to complete 10 tests. This does not include the warm-up time. Throughput time included the time to swab, analyze, run cleaning cycles to clear the machine, and to run blank swabs for 10 tests. All of these activities would be com- mon in regular field use. Therefore, each test took, on aver- age, 84 seconds to complete. Ease of Use and Training Requirements. The equipment is relatively simple to operate. One minor problem noted was that under sunny conditions it was difficult to read the dis- play when the equipment was operated outdoors. However, it is highly recommended that security personnel who are going to operate this equipment receive at least 1 day of train- ing from the manufacturer. The cost and time commitment is minimal, and the training provides the operator with a solid foundation for using the equipment effectively. Currently, there are different training packages provided for the selected device. The cost can range from $1,500 to $2,800, depend- ing on the type of training. Ideally the training should take place at the transportation facility. Instruction needs to be provided in the areas of the following: • General operating procedures, • Replacement of consumables, • Cleaning down the equipment, • Use of the verification standard stick, and • Operating parameters. Maintenance Costs. At the time this report was pub- lished, the manufacturer had not established the need for an annual maintenance cycle. Consumables. Consumables for the detection equipment tested include batteries, wipes, and filters. The cost of these for 1 week of heavy operations, as in this study, was estimated to be $90. In addition to the consumables used by the detection equip- ment, it is also recommended that the operators use gloves. The trace detection equipment used in this study is very sensitive

25 and susceptible to contamination. It is highly recommended that users wear latex gloves during operation of the equip- ment, particularly when verification standard sticks are used. While concern about allergic reaction to latex gloves is an increasingly reported problem, it was found that these gloves offered the best protection. In particular, the inexpensive nitrile gloves, which are finding increasing favor, can in fact be a contamination source and should not be used with this equipment. False Positive Alarms. One aim of this study was to un- cover adverse conditions that could affect the device’s oper- ation. These conditions might include operation where exter- nal fumes exist, such as near cleaning closets, combusted diesel fuel, copy shops, hairdressers, or restaurants. None of the external factors in these places seemed to significantly affect the outcome of tests. For example, test results were not affected during operations in bus maintenance shops with oil visibly covering the ground. The false positive alarm rate noted in this study was a relatively minor (1.7%) and is con- sistent with the false alarm rate seen at airports with trace detection equipment currently deployed. The false positive alarm rate did not represent a significant problem. Site Survey. It is recommended to any transportation facility purchasing this equipment that a site survey be per- formed. That is, the equipment should be operated within the expected working environment, and the false positive alarm patterns should be noted. In one of the test facilities, it was noted that there were materials being used in a maintenance area that were not compatible with the instrument. In this one instance, the unit registered a number of false positive alarms associated with a repair/maintenance facility. It is presumed that there was a source of interfering material at this location that was responsible for the false positive alarms. It is rec- ommended that such activities be identified by performing a site survey and be noted in local operating procedures. False Negative Alarms. The alarm levels of the instrumen- tation tested was found to be 10 ng for the high explosives and about 70 ng for the ammonium nitrate. These levels are con- sistent with the manufacturer’s specification. During this study, tests were conducted using sample quantities of explosives that were at, or even below, the manufacturer’s specified alarm level. 4.2 APPLICATIONS OF THE PORTABLE INSTRUMENTATION There are a number of potential circumstances in which portable EDDs could aid officials in the transit environment. In many of these situations, the trace detection equipment could offer meaningful aid. In others, the current technology is problematic. 4.2.1 Abandoned or Lost Articles One problem faced by all transit authorities is the issue of evaluating lost or abandoned packages. The procedures for handling abandoned packages varied among the test locations in this study. However, most transit officials interviewed are making a visual evaluation and then determining if EOD units should be notified or if it is safe for the transit official to directly examine the abandoned object. In many cases, the object is handled and inspected without contacting law enforce- ment. In cases of suspicious packages, transit officials are calling EOD units to evaluate the package. While it would be very desirable to be able to perform a screening prior to call- ing officials, there are some equipment limitations. The equipment used in this study appears to be reliable and sensitive enough to be used as a screening tool, but there are some limitations in using the equipment in this way. The porta- bility, ease of operation, short setup time and sensitivity of the system makes it attractive for this application. However, taking swab samples is an issue when examining abandoned/ lost articles. In order to conduct a test, a swab must be rubbed by hand over the article being tested. This requires the operator to have to handle the package extensively, but it does not require the operator to open the package. In cases where the package has been evaluated by the transit official as likely to be harm- less and the operator is going to open it or dispose of the arti- cle, it is not an issue to take a swab sample. The operator has already made the decision to handle the object. In this case, the use of the detection equipment provides a level of pro- tection to the operator. However, in the case of a suspicious abandoned package, the operator may make the decision not to handle the pack- age for safety reasons. In this case, the trace detection equip- ment provides little utility. The extensive handling necessary with use of detection equipment may be deemed unsafe, and the official has little recourse other than calling for EOD to examine the object using dogs or X-ray equipment, neither of which requires handling the object. Deciding not to han- dle a package that is suspected to contain an IED precludes the use of virtually all trace detection systems that require a swab sample. 4.2.2 Screening 4.2.2.1 People Screening It is possible to use portable detection equipment to screen passengers, but there are severe limitations with this use. The first limitation is the throughput. While the average inspec- tion time of 84 seconds is not significant for inspecting an abandoned package, it is a considerable period of time for a commuter who needs to board a train, not to mention the amount of time spent waiting in line to be inspected. The open system is part of transit culture. Unless the culture changes,

26 this type of use is not recommended. Because there are usu- ally multiple entries to a single station, it makes no sense to line transit passengers up at one entrance for random checking of packages and bags before boarding (as is done in airports). An attacker could easily use an entry point where there is no screening. Further, the “just-in-time” nature of the subway does not leave commuters with the option to stop for a check. The delay caused by transit passenger screening could lead transit commuters to use other forms of transportation. That is not a desirable outcome. 4.2.2.2 Vehicle Searching One potential application is to provide a level of inspec- tion of vehicles as they enter tunnels or check points in the transit environment. The team randomly tested 30 vehicles in a parking lot to determine the device’s performance with swabs of unknown particles. It is possible that false alarms could occur from elements on the vehicles, such as waxes and gas or oil residue, or other possible disruptions to the device. The tests were performed by swabbing only the out- side of the vehicles; samples were taken from surfaces such as the door handles, door and trunk locks, and wheels. This type of screening may be suitable for this device. All tests returned the correct results, without false alarms. Ideally, an internal check of the vehicle should be performed as well. A limitation to use of this device for vehicle screening outdoors is that it can’t be used in rain or snow. These weather condi- tions may result in downtime for the screening procedure. 4.2.2.3 Luggage/Cargo/Packages Attention to train and bus security has increased steadily the past few years. Having baggage screeners operating on trains and buses in the same way that they operate in airports would create a costly dilemma of having to design passenger- screening areas in train and bus stations. As mentioned, the current just-in-time nature of commuter traffic on trains and buses may not permit the use of the portable EDD to screen passengers because there would need to be a certain level of queuing prior to boarding. Nonetheless, because the device can be set up in a relatively short amount of time and uses a small amount of space to operate, it could be useful in ran- domly screening passenger luggage just prior to loading it onto long distance bus or train trips. For instance, before loading luggage onto a bus, it is usually collected adjacent to the vehicle and loaded by an employee of the transit agency. While passengers are loading, an explosives screener could randomly test the luggage. 4.3 RECOMMENDATIONS FOR FURTHER DEVELOPMENT A major concern in the application of the EDD in the tran- sit environment was the sample collection. Rubbing the arti- cle with a swab is not recommended for all scenarios. A vapor-based system would help, in that it does not require the operator to touch the package. 4.3.1 Vapor-Based Detection The greatest limitation of the equipment reviewed in this study was that the operator is required to handle the object to collect a swab sample. Improvements that could be made to change the sampling method are desirable. A vapor-based system, which would sample the air surrounding the package without touching it, would be superior. The problem is that modern explosives are not very volatile, and the existing equipment does not have the sensitivity to directly detect the explosive vapor. There are a number of possible approaches to developing equipment that can directly detect the explo- sive vapor. The first approach is to develop more sensitive equipment. However, the equipment tested in this study is some of the most sensitive equipment available today. Making the equip- ment more sensitive will take extensive development time. The second approach is to develop new sample collection equipment to be used with the existing equipment. 4.3.2 Post-Blast Residue An application of the EDD is the use of the device to eval- uate post-blast residue. The EDD may be a tool to aid in col- lection of evidence in the field. The information collected from interviews with transit officials suggested that this tech- nology could provide significant help in investigating bomb crime sites. Parts from a car after a blast can be investigated for residues of explosives.