Explosives Detection Still Crucial for Transportation

Identifying and detecting the presence of explosive materials or substances using explosive detection systems is not only necessary, they are key pillars of ensuring public safety.

Those who have worked in aviation will likely remember Umar Farouk Abdulmutallab popularly referred to as the “underwear bomber” or “Christmas bomber,” a Nigerian terrorist who attempted to detonate plastic explosives hidden in his underwear. And what about Richard Reid — known as the “shoe bomber” — who tried to detonate his shoes which were filled with explosive material on a flight from Paris to Miami in 2001.

The illicit use of explosives has become an all-too-real event in the modern world. According to Global Terrorism Index (GTI), in 2023, there were approximately 3,350 explosive-related attacks in the world. High-profile terrorist attacks in public transportation-related venues, such as airports, train stations, ports and border control points have highlighted these areas’ vulnerability to explosive attacks.

Explosive detection systems play a crucial role in ensuring public safety by preventing these attacks. An explosive detection technology is a device or system designed to identify and detect the presence of explosive materials or substances, whether they be military, conventional or homemade, thereby avoiding catastrophic and damaging events. According to Selbyville, Del.-based Global Market Insights, the explosive detectors market size was valued at USD 8.95 billion in 2023 and is anticipated to register a CAGR of over 12% between 2024 and 2032.

“A vigilant guardian,” that is how John Johnson, senior director of strategic marketing and business development at 908 Devices, Boston, describes explosive detection’s role in meticulously screening passengers, luggage and cargo for potential threats. “Its presence serves a dual purpose: not only does it identify dangers, but it also acts as a powerful deterrent, discouraging attempts to smuggle explosives onto transportation systems. The technology’s ability to provide rapid threat identification is crucial, enabling swift responses that minimize disruptions and maintain the smooth flow of travel. Ultimately, these capabilities coalesce to significantly enhance the overall safety of both travelers and transportation personnel.”

Explosives and Transportation Security

Explosive detection technology is vital for transportation security; identifying explosive threats before they reach their transportation targets. “Transportation lies at the heart of the everyday life of people across the world,” says Logan Cunningham, sales and service, US Testing Equipment, Vancouver, Wash. “The importance of transportation networks makes them a prime target and at risk of harm that could cause loss of life, economic impact and destabilization that can come with losing the feeling of security in an integral part of everyday life.”

Cunningham believes it’s the integral nature of transportation to everyday life that causes some of the biggest hurdles to securing these targets from potential explosives threats. He explains, “Modern transportation, regardless of purpose or specific industry, is typically a high-volume and tightly coordinated effort. This brings the requirements for fast, consistent and reliable detection that is economical and easily deployable. Unlike, for instance, military or correctional screening of goods or people, where security typically has the utmost priority and other factors (such as time or efficiency) can be deprioritized, transportation networks are often built on their efficiency (both time and economic) and an explosive detection solution should be able to be reasonably integrated.”

Nicholas E. Ortyl, chief engineer, security enterprise solutions at Leidos, Reston, Va., cites the following key important factors of explosive detection in transportation security:

• Threat Mitigation: Detects explosives at high-risk hubs like airports to prevent attacks.

• Safety: Safeguards travelers and staff by neutralizing threats before they cause harm.

• Regulatory Compliance: Helps meet security standards from government agencies like the TSA and ECAC.

• Operational Continuity: Minimizes false alarms and delays, while enabling high throughput screening environments.

Ortyl cites the following unique aspects for it:

• Varied Environments: Adaptable for different settings (e.g., aircraft, buses, cargo).

• High Throughput: Each system can complete hundreds of screenings per hour, quickly and accurately.

• Layered Approach: Combines multiple systems and human oversight for comprehensive threat detection.

• Broader Integration: Works with biometrics, surveillance and other systems to enhance security.

• Operational Flexibility: Must be portable, fast, and reliable with minimal disruptions.

Robert Stokes PhD, director detection and security, Molecular Spectroscopy at Agilent Technologies, Santa Clara, Calif., agrees that transportation settings are among the most demanding environments for threat and explosive detection equipment and technology. “Systems must deliver exceptional detection capability and maintain low false-alarm rates within extremely short processing times. Additionally, detection technologies need to consistently perform over millions of cycles. It is also crucial that any screening technology is user-friendly and produces clear, unambiguous results for security operators to minimize disruptions to screening operations and the flow of commerce.”

The unique environment of transportation systems has shaped explosive detection technology in distinctive ways. “High-throughput screening capabilities are essential to manage the immense volume of passengers and cargo that flow through transportation hubs daily,” Johnson says. “These systems must maintain a delicate balance, delivering accurate results while minimizing false alarms to prevent unnecessary delays that could ripple through the entire transportation network. The technology must also be versatile, capable of detecting a wide spectrum of threat materials, as transportation infrastructure remains a prime target for various types of attacks. Moreover, the portability of modern detection systems allows for flexible deployment across different areas of transportation hubs and even on moving vehicles, creating a dynamic and adaptive security presence.”

Detecting Homemade Explosives

Detecting homemade explosives (HMEs) poses significant challenges in transportation security due to their unique characteristics and the non-standard nature of the devices. Unlike military-grade explosives with distinct chemical signatures, HMEs often have varied and unpredictable chemical compositions, making them more difficult to identify.

Andy Foland, chief technology officer, security enterprise solutions at Leidos explains, “HMEs can be unstable, varying in sensitivity to heat, shock or friction, which increases the risk during handling for obtaining signature data. This also poses challenges for safely neutralizing threats when detected. Detection systems designed with more consistent formulation in mind can result in high false-alarm rates, or a need to augment signatures or capabilities with new detection modalities.”

“These improvised threats are frequently crafted from common household items, further complicating the detection process as they can be easily mistaken for benign materials,” Johnson says. “The lack of a consistent chemical signature adds another layer of complexity to their detection. Homemade explosives tend to be much more sensitive than military explosives, making them prone to igniting from slight changes in pressure or exposure to an energy source. For this reason, certain technologies that utilize lasers can be dangerous to use when explosives are potentially present.”

Cunningham explains that HMEs utilize a range of explosive materials, delivery methods and quantities that can be difficult to detect based on packaging or location if the right technology is not being used to address the threat. “This is also where additional features such as software additions can aid in potential threat identification to aid operators’ inspection.”

Mitigating HMEs requires flexible and advanced detection systems that can account for a wide range of materials, formulations and concealment methods used in their construction. 908 Devices’ MX908 addresses these challenges and is equipped with sophisticated algorithms and broad detection capabilities, and is particularly adept at identifying these diverse threats in transportation settings.

Because of HMEs’ difficult-to-detect common household chemicals, London, England’s Smiths Detection has calibrated its advanced trace-detection technologies to detect a wide range of chemicals, addressing the variability in HME compositions. “This flexibility is vital in identifying these explosives, which often lack consistent ingredients but pose serious threats to transportation security.”

HEIDM Program

Recent HME attacks have further bolstered the need for a strong explosive characterization program, and have served to re-emphasize the benefits of United States Department of Homeland Security’s Homemade Explosives Identification, Detection and Mitigation (HEIDM) Program.

As HME threats are often made of common commercial items, it is a challenge to distinguish true HME threats from the many innocent gels and liquids in personal baggage or cargo. The HEIDM Program is a crosscutting portfolio, meaning the information collected in this program feeds into TSA to benefit several science and technology programs, and has focus areas on:

• Explosive detection characterization.

• Threat assessments and prioritization.

• Tests, tools and methodologies relating to explosives research and risk mitigation.

• The HEIDM Program ensures the explosives community has a clear understanding of homemade and emerging explosive threats to:

• Improve detection technology.

• Develop detection requirements.

• Inhibit the unlawful use and manufacture of HMEs.

• Provide a solid foundation for solutions to counter the threat, such as pre-planning tools for responders and event planners.

Detection Innovations

Technology advances for detecting explosives in both ever-evolving and emerging threats have countered their use and resulting impacts. Innovations have made detection more accurate, efficient and less intrusive, ensuring both security and smooth transportation operations. Cunningham says this has occurred not only in the increased library of detectable substances but also the concentrations (trace particulates) and the ability to discriminate or differentiate between non-target substances and suspected explosive materials.

Foland says explosive detection has evolved from basic X-ray and metal detectors to advanced systems utilizing AI/ML, radiofrequency (RF) waves, and Ion Mobility Spectrometry (IMS). “Early methods focused on detecting metallic threats, but the use of X-ray, RF, wideband FR complex impedance, Raman spectroscopy, capillary zone electrophoresis and IMS has enabled the identification of non-metallic explosive materials. Modern innovations, such as millimeter-wave imaging, 3D Computed Tomography (CT) scanners, and standoff detection allow for non-invasive, high-accuracy screening of passengers and baggage. AI-driven systems improve detection speed and accuracy, and reduce false alarms, while integrating them with broader security measures can enhance overall situational awareness.”

“Explosive detection technology has evolved significantly, integrating artificial intelligence into systems like (Smith Detections’) HI-SCAN 6040 CTiX, which automates threat recognition and reduces human error,” says Joachim Petry, business development manager, X-ray diffraction at Smiths Detection. “[We] also offer computed tomography and 3D-imaging solutions for more detailed and reliable screening of luggage and cargo, allowing threats to be identified with minimal manual intervention. Portable systems like the IONSCAN 600 provide flexibility for deployment in a variety of transportation settings. These systems are also non-invasive, relying on trace detection technologies like IMS without the need for physical sampling, enhancing both security and passenger experience. [Our] iCMORE technology integrates AI and deep learning algorithms into our X-ray detection systems. This enables faster decision-making and more accurate threat identification, significantly reducing false alarms and enhancing operational efficiency in busy transport environments.”

Integrating machine learning approaches that enable algorithms to quickly adapt to changes in the threat landscape and the flow of commerce has been very beneficial. Stokes say, “These advancements include enhanced detection capabilities, allowing modern systems to identify a wider range of explosive materials with greater accuracy, and reduced false alarms, as machine learning helps distinguish between actual threats and benign items. Additionally, faster processing times enable rapid screening without compromising security, while improved user interfaces provide clear and unambiguous results for security operators. Furthermore, newer systems are designed to perform consistently over millions of cycles, ensuring long-term reliability in demanding environments. It is critical that any explosive detection technology is robust enough for demanding screening operations and can be safely and effectively utilized by security personnel who may not be hazmat or laboratory trained.”