Patent Publication Number: US-2009219390-A1

Title: High Throughput Security Screening System for Transportation Applications

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/756,574, filed Jan. 6, 2006. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to the art of security screening systems and, more particularly, to a high throughput security screening system employed at ground transportation access points. 
     2. Discussion of the Prior Art 
     Since Sep. 11, 2001, protection against terrorist threats has become a national priority. At present, most systems are heavily focused on aviation security. However, more recent attacks, such as the Madrid train station bombings on Mar. 11, 2004 and the London subway bombings on Jul. 7, 2005, have focused greater attention on the vulnerability of ground transportation systems. Various types of threats have been postulated, including attacks using explosives, chemical and biological agents, as well as nuclear and radiological agents (dirty bombs). The diversity of this threat has created complex security challenges. As a result, total expenditures related to Homeland Security topped $100 B in 2003 and billions more have been allocated in Federal, Supplemental Appropriations and State/Local spending. Accordingly, growth in the homeland security industry is expected to be vigorous over the next decade. Motivated by the wide diversity of potential threats, and by the inadequacy of currently available systems, government investments in research and development are stronger than ever. In addition, recent increases in funding for ground transportation security systems have highlighted the desire to improve protection, especially against explosive threats, in these facilities. 
     Of the various threats postulated, explosives remain the number one choice of most terrorists. Indeed, many experts have noted that in the case of terrorist activity, statistical evidence strongly indicates that the primary threat is explosives, i.e., bombs. Historical evidence suggests that even moderately effective portal screening, used to screen 100% (or nearly 100%) of personnel, increases the operational risk to would-be attackers and therefore poses a significant deterrent. Unfortunately, screening 100% of all passengers in, for example a public ground transportation hub, would create a significant throughput challenge. Given the large number if individuals who travel by public transportation on daily basis, presently available screening systems would create long queues or delays that would create an economic burden and impede commerce. 
     In the case of explosive screening, current systems can cost more than $1 M per portal for bulk explosives detection systems and tens of thousands of dollars for trace explosives detection systems. In addition, installation and annual maintenance costs often exceed the systems&#39; purchase price. Some newer bulk detection systems, such as millimeter wave systems, have been proposed for high-throughput applications. However, millimeter wave systems suffer from significant signal processing and automatic target recognition demands as the systems are not specific to explosives. In addition, system responses from threat objects are highly dependent on a number of variables such as the object&#39;s position relative to the sensors, and other factors that are not easily controlled. In the case of trace explosives, currently deployed detection systems were developed primarily for the use of analytical chemists in laboratories and only later adapted for use in the field. Thus, currently available trace explosive detection systems suffer from very long clearance times after positive detections (15-30 minutes), have exceedingly high false alarm rates, and require extensive training to ensure proper use and maintenance. 
     Conventional explosive detection systems, developed primarily within constraints imposed by aviation security, are not suitable for ground transportation screening applications. Conventional systems are large, operator intensive, represent high capital and maintenance costs, do not have sufficiently high throughput, and suffer high false alarm rates. As such, they can most suitably be implemented in facilities or industries where significant choke points exist due to other operational constraints. However, as conventional systems demand dedicated processes, procedures, operators, and/or facilities for operation, they are not amenable to incorporation in other, highly distributed systems such as the thousands of turnstiles or entry points for ground transportation systems. 
     Conventional systems are also not suited for detecting trace amounts of explosives that may be found on passengers. Explosive contamination can vary widely over small spatial distances. Evidence shows that trace residue levels can differ by 10,000 fold over distances as short as a few centimeters. Unfortunately, currently available trace explosive detection systems are limited in their ability to obtain proper samples. More specifically, currently available systems only sample from limited spatial areas, with swipes of these areas being provided to a fixed base system. Obtaining samples from secondary surfaces such as tickets, credit cards, Driver&#39;s licenses, passports, or the like in conventional trace detection systems is known in the art. However, these systems require that a sample be collected from the secondary source using a swab or swiping technique. This swab or swipe then undergoes a thermal desorption step which is time intensive and which also necessarily restricts the amount of area that is interrogated for analysis. 
     Attempts to automate the swiping process involve the use of dedicated equipment that is not suitable for integration with existing ground transportation equipment. Furthermore, conventional systems do not incorporate a complete architecture that permits time-phased analysis of a sample to “buffer” high throughput demands, nor do existing systems provide a means to correlate the sample results with secondary information sources such as time, date, location, photo, video data and the like. As stated above, existing systems do not lend themselves to incorporation in existing ground transportation systems, such as fare collection systems, stand alone information booths such as fare card purchase systems, or other collection systems. 
     In summary, currently available conventional screening systems suffer from many disadvantages that have been described previously, including high cost, low throughput, high false alarm rates, operational complexity, high maintenance and training requirements, poor sample recovery, lack of spatial information on the sample recovered, and the like. These limitations have created a significant barrier to the use of existing systems in ground transportation applications. 
     Based on the above, despite the existence of security screening systems in the art, there still exists a need for a security screening system that can be incorporated into existing ground transportation systems. More specifically, there exists a need for a security screening system that enables a high throughput in order to reduce passenger wait times yet still ensures thorough screening for all passengers. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a high throughput security screening system employed at access points of a ground transportation system. The screening system includes a main housing having an input port provided for receiving exhibits such as fare cards, a sampling media positioned in the main housing that obtains a trace sample from the exhibits and a processing system for scanning the trace sample for a threat indicator. In accordance with the invention, the screening system also includes a memory for storing or buffering information related to threat indicators. With this arrangement, the screening system is capable of processing a high volume of exhibits while maintaining a high level of security and mitigating passenger inconvenience or wait times. 
     In further accordance with the invention, during periods of high volume processing, such as rush hour or the like, the screening system buffers trace samples for later processing. The trace samples are correlated to information obtained from passengers passing through the screening system. Thus, in the event that a particular trace sample tests positive for a threat indicator, security personnel are provided with information about the passenger(s) that tested positive. For example, security personnel are provided with various pieces of information, such as time/date of use of the exhibit, video and/or still photographs, audio signals and the like, which can aid in the apprehension and possible detention of the passenger. The screening system also employs various algorithms that allow security personnel to rapidly address false alarms so as to further ensure minimal disruption of passenger flow. 
     Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of a preferred embodiment when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  is a perspective view of an entrance to a ground transportation system employing a security screening system constructed in accordance with the present invention; 
         FIG. 2A  is an example of an exhibit shown in the form of a fare card employed in connection with the ground transportation system of  FIG. 1 ; 
         FIG. 2B  is an example of an exhibit shown in the form of a plurality of tokens employed in connection with the ground transportation system of  FIG. 1 ; 
         FIG. 2C  is an example of an exhibit shown in the form of paper currency employed in connection with the ground transportation system of  FIG. 1 ; 
         FIG. 2D  is an example of an exhibit shown in the form of a smart/credit card employed in connection with the ground transportation system of  FIG. 1 ; 
         FIG. 3  is a top, cut-away view of an access barrier having a sample collection device employed in connection with the security screening system of  FIG. 1 ; 
         FIG. 4  is a flow chart illustrating operation of the security screening system of  FIG. 1 ; 
         FIG. 5  is a graph illustrating a data capture and recording portion of the security screening system; 
         FIG. 6  is an example of a snap shot of a computer screen showing a regional overview of the ground transportation system associated with the security screening system; 
         FIG. 7  is an example of a snap shot of a computer screen showing a local overview of the ground transportation system associated with the security screening system; and 
         FIG. 8  is an example of a snap shot of a computer screen showing a security event occurring at a station of the ground transportation system associated with the security screening system. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With initial reference to  FIG. 1 , a high throughput security screening system  2  constructed in accordance with the present invention is shown employed in connection with a ground transportation system (not shown) that is accessed through, for example, a subway entrance  3 . As shown, arranged at subway entrance  3  is an information/security booth  4  within which is housed a local control portion  5  of security screening system  2 . Local control portion  5  includes a central controller or CPU  6  that is linked to a display  7  and an input device  8 . Local control portion  5  is also shown with a communication link  9 . As will be discussed more fully below, an operator sitting in information booth  4  can set a threat level for security screening system  2  through input device  8  or, alternatively, security screening system  2  can be updated remotely through communication link  9 . 
     In accordance with the invention, security screening system  2  also includes a screening portion  15  which takes the form of a plurality of access barriers or turnstiles, one of which is indicated at  16 . Although screening portion  15  is shown at access barrier  16 , it could also be separated therefrom. In any case, in order to gain access to ground transportation through subway entrance  3 , a user must first insert an exhibit, such as shown at  20 A- 20 D in  FIGS. 2A through 2D  into access barrier  16 . More specifically, a user or passenger will either already have or will purchase an exhibit from a kiosk or vending machine  26 . In accordance with the invention, the exhibit can take a wide range of forms, including a fare card  20 A such as shown in  FIG. 2A , tokens  20 B as shown  FIG. 2B , a currency note  20 C as shown in  FIG. 2C , a credit or smart card  20 D as shown in  FIG. 2D , or the like. As will be discussed more fully below, access barrier  16  scans the exhibit for various threat indicators in order to determine whether a particular passenger poses a potential threat to, for example, the ground transportation system. In addition to scanning passengers at access barrier  16 , security screening system  2  includes an ID portion  29  including multiple imaging devices shown in the form of cameras  30  and  31  which are slaved or cued to security screening system  2  and selectively activated to capture still and/or video images of a passenger or passengers associated with each exhibit being inserted for scanning. Although not shown, ID portion  29  also captures audio signals from select ones of the passengers passing through entrance  3 . 
     As shown in  FIG. 3 , each access barrier  16  includes a main housing  40  having front, rear and opposing side walls  42 - 45 . A retractable barrier  47  projects outwardly from side wall  44 . Retractable barrier  47  shifts into main housing  40  in order to allow a passenger to pass through subway entrance  3  after an appropriate exhibit has been inserted into an input port  50  arranged on front wall  42 . As will be detailed more fully below, not only does inserting the exhibit into input port  50  enable the passenger to gain access to the ground transportation system, but access point  16  also performs a security screening of the exhibit. More specifically, arranged within main housing  40  is a screening system  53  that obtains and analyzes a trace sample from the exhibit as will be discussed more fully below. 
     In accordance with the invention, screening system  53  includes a pair of friction rollers  56  and  57  that guide exhibit, for example exhibit  20   a,  into contact with sampling media. More specifically, exhibit  20   a  is guided between, and brought into contact with, first and second sheets of sampling media sheets  59  and  60  to obtain a trace sample. Typically, once the trace sample is collected, the exhibit is returned to the passenger. Sampling media sheets  59  and  60  are preferably treated with an adhesive, pre-impregnated catalysts and/or other pre-treatment medium. Unused portions of sampling media sheets  59  and  60  reside on respective ones of new media spools or rolls  62  and  63 , with used portions of media sheets  59  and  60  being retained on corresponding ones used media spools or rolls  66  and  67 . Screening system  53  could also include additional spools/rolls (not shown) to store used sampling media for later analysis during times of high passenger volume. As will be discussed more fully below, after contacting exhibit  20   a , the sampling media sheets  59  and  60  are passed by an applicator  71 . Applicator  71  deposits a chemical reagent onto a portion of sampling media sheets  59  and  60  prior to processing. More specifically, applicator  71  directs a reagent  74  on the portion of sampling media sheets  59  and  60  that contracted the exhibit. In any event, as shown, applicator  71  is separated from new media rolls  62  and  63  and used media rolls  67  and  68  by respective shields  75  and  76 . Shields  75  and  76  prevent any debris or reagent  74  from inadvertently contacting sampling media sheets  59  and  60  and potentially causing contamination that may corrupt the trace sample. 
     In addition to applicator  71 , screening system  53  includes a secondary processing unit  78  which add overall controls in connection with accepting exhibit  20   a,  rotating rollers  62 ,  63 ,  66  and  67 , injecting reagent  74  and performing the threat residue analysis. Screening system  53  further includes an imaging bed  83  and an image scanner  86 . Image scanner  86  is preferably in the form of an optical explosive detection sensor which unobtrusively measures explosive contamination from a secondary source, e.g., sampling media sheets  59  and  60 . For example, screening system  53  could employ spatially resolved detection that utilizes photoluminescent polymers/copolymers or other color change, luminescent or fluorescent techniques to detect threat residue. Finally, screening system  53  is shown to include a number of rollers/guides  89 - 92  which ensure that sampling media sheets  59  and  60  are properly guided from new media rolls  62  and  63  to used media rolls  66  and  67 . 
     Reference will now be made to  FIG. 4  in describing a preferred method of operation of security and screening system  2 . As noted above, a threat level is initially established for screening system  2  at information booth  4  or, remotely through communication link  9 . As shown in step  109 , the threat level preferably establishes a sensitivity level for screening system  2 . More specifically, during a low threat level, screening system  2  will employ a low detection threshold in order to provide a high throughput rate. However, during a high threat level, screening system  2  will set a high screening threshold or increased sensitivity in order to increase the likelihood of detecting any and all potential threats passing through entrance  2 . Setting a higher screening threshold decreases throughput times and increases screening time. However, as will be discussed more fully below, screening system  2  includes various systems to mitigate a loss of throughput due to increased sensitivity. In any event, screening system  2  initially receives an exhibit  20   a  having a sample surface in step  112 . Upon receipt of an exhibit, a trace sample is collected in step  114 . More specifically, sample media sheets  59  and  60  are brought into contact with the exhibit to obtain a trace sample. The trace sample is then analyzed in step  117 . 
     During analysis, chemicals (reagent  74 ) are applied to the trace sample in step  120 , and secondary processes, such as heated drying, are optionally conducted in step  123  before the trace sample is scanned in step  127  to obtain a scanned image of the trace sample. Reference can be made to co-pending U.S. patent application Ser. No. 11/525,344 entitled “System and Method For Optimization of Trace Chemical Sample Collection and Analysis in Personnel Screening and Security Systems” filed on Sep. 22, 2006, which is incorporated herein by reference, for a detailed explanation of one preferred form of threat analysis system. However, in short, the scanned image of the trace sample is then subjected to a filtering, processing and analysis step  130  which generates a scaled risk indicator in step  134 . Processing of the scanned image can include serial and/or parallel processing depending upon a particular designed sensitivity level and throughput. The scaled risk indicator is employed to determine whether the trace sample contains a threat residue. 
     At this point, it should be noted that analysis portion  117 , depending upon the established threat level and, optionally, time of day, e.g. rush hour, will collect images from ID portion  29  in step  135  and establish a date/time stamp for each trace sample in step  139 . More specifically, during rush hour and other high volume times, an image and date/time stamp is collected for each exhibit passing into screening system  53 . The scaled risk indicator obtained in step  134 , the image obtained in step  138  and date/time stamp collected in step  139  are stored in a memory or buffer  143  for later evaluation. With this arrangement, screening system  2  can ensure a high throughput even during times of high passenger volume and high sensitivity. After the high passenger volume has subsided, buffer  143  is evaluated for any potential threat indicators. Any trace samples containing a threat indicator are correlated with a particular exhibit, image and date/time stamp and passed on for further security actions. Alternatively, during times of high passenger volume, sample media could be stored on a buffer roll (not shown) for subsequent forensic evaluation when processing demands are lower. During all other times, analysis portion  117  provides real time analysis on the trace samples. 
     If analysis portion  117  reveals no threat indicator on the trace sample, information is passed to a data storage step  145 . If a data storage flag is set high, information is stored for a preset time period in step  146 . That is, the information is preferably passed onto a data storage device (not shown) and stored for a predetermined time period. If the data storage flag is set low, the information is simply erased at  147 . Conversely, if analysis portion  117  signals a detection event  160 , i.e., determines the presence of a threat indicator, data associated with the detection event is stored in step  153 , an alarm is set and security actions are executed in step  154 . More specifically, as best shown in  FIG. 5 , in the event detection system  53  identifies a detection event  160 , data capture and video is saved for a time period T. Time period T represents a period of time before and after the detected event. In this manner, security personnel are provided with additional help in determining who and what may have triggered security system  2 . By only storing the data related to a sensed, potential threat, storage requirements are minimized. However, if a positive threat detection is made, the invention advantageously provides for the storage of data from both before and after the screening process. 
     At this point, it should be recognized that, by providing controls at information booth  4 , any alarms can readily be resolved without triggering a full blown security response. That is, in the event that an alarm is signaled, a security person or operator located in information booth  4  can resolve any false alarms by real-time examination of a ticket to verify the result, re-scan a particular individual and/or take remedial measures in order to mitigate the need for a significant security response which would disrupt passenger flow. 
     In further accordance with the present invention, in addition to providing localized monitoring at, for example, entrance  3 , security screening system  2  also includes a central control portion  180  that monitors the ground transportation system on various levels such as depicted in  FIGS. 6-8 . More specifically, information obtained from each subway entrance  3  is passed, via communication link  9 , to a main control center (not shown). At the main control center, operators can monitor various computer displays which show various stations at a regional level such as shown at  186  in  FIG. 6 , a local level such as shown at  188  in  FIG. 7 , and a station level such as shown at  190  in  FIG. 8 . 
     On the regional level, operators can monitor each station, threat level, current operating procedures and status for a particular region of the ground transportation system. In the event of an alert resulting in the setting of a severe threat level, such as shown at station  33 , an operator can move to the local level  188  of  FIG. 7  which provides an overview of the particular location of station  33  in a localized grid map. An operator can also zoom to the particular station  33  as shown at  190  in  FIG. 8 . That is, in the event that an alarm is triggered in, for example, station  33  an operator can shift to the particular station screen  190  which depicts the particular entrance at issue, both graphically as in screen  220  and via video as in screen  222 . In addition, the operator can view an image of the exhibit in question in screen  223 , as well as video and still images of the passenger associated with the exhibit in screens  224  and  225  respectively. This particular feature enables authorities to direct personnel to the particular station and/or individual that triggered the alarm. 
     Based on the above, screening for explosives and explosives-related compounds in ground transportation facilities is of particular interest; however, the system may incorporate multiple security sensor systems including chemical agent, biological agent, radiological substance, metal detection, biometric identification sensors, among others, for the purpose of identifying security risks. Screening may occur in private and/or public facilities such as train stations, metro stations, bus stations, commuter rail stations, or other like facilities, and may be used in regulated or unregulated environments. The system is a fully integrated hardware and software system that incorporates at least one security sensing system, preferably a trace explosive detection system, and a method for resolving alarms and/or storing additional correlated information for immediate security use or for later security, law enforcement or forensics purposes. This information may include time and date, location, video data, an image of the subject causing an alarm, audio signals, among other data. Notably, the purpose of this system is to provide a capability to identify threats early in their development by identifying high risk individuals and/or behaviors. The system provides a means of interaction that is unobtrusive, high throughput, dynamically adjustable based on threat level, and allows for ‘soft’ false alarm resolution to avoid detaining subjects unnecessarily. An important feature of this system is that the sample is provided by the subject rather than requiring the use of dedicated personnel to obtain a sample and further, that the sample can be obtained and analyzed quickly. 
     Although described with reference to a preferred embodiment of the invention, it should be readily understood that various changes and/or modifications can be made to the invention without departing from the spirit thereof. For instance, while described with respect to a ground transportation system such as a subway, the present invention could also be employed in connection with user access to various transportation systems, including trains, buses and the like. In addition, to capturing video feed of detecting the event, the security scanning system could also capture audio signals. Furthermore, while the system is described as obtaining a trace sample from an exhibit in the form of an object received from a passenger, exhibits having trace samples may also be obtained directly from passengers such as through fingerprints, thumbprints, etc. by a contact pad or the like which establishes the input port. In general, the invention is only intended to be limited by the scope of the following claims.