As public transportation is the backbone of a city, monitoring public transit spaces for potential biological or chemical hazards without slowing anyone down is important. Quickly detecting and mitigating biological or chemical threats in the subway is critical for preventing the spread of hazardous materials. However, technologies that are currently in use do not perform fast enough for a subway environment, and false alarms may cause unnecessarily disruptive and expensive closures.
Hence, the Department of Homeland Security (DHS) and its public transportation partners have been developing and perfecting various sensor technologies for public transit through a portfolio of collaborative projects with the City of New York, to help protect high-density urban areas against threats. The bio-detection sensor tests and evaluates cost-effective technologies to detect chemical and biological threats inside an actual subway environment, as well as mitigation strategies if threats are detected.
A testbed is a real-world environment where researchers can see how the technology performs. Several testbeds already exist in New York, examining new technologies for different hazards. The CBT is designed to detect a wide range of threats with the help of chemical and biological sensor technologies. The initial phase of the bio-detection sensor focuses on biological threats as they are more difficult to detect early during the incubation period and can multiply for days before being noticed. On the other hand, when a chemical hazard is released, the effects are typically immediately visible.
The current testbed consists of eight secured cabinets in a New York City subway station. The bio-detection sensors are not yet installed, but inside the cabinets presently lie environmental sensors, power and communication equipment, and a nearby command centre that will support the functioning of the sensors.
After the new bio-detection technology is installed, researchers will gather data to assess the technologies’ performance. These data will include false alarm rate, probability of detection, time to detection and cost of ownership, as well as environmental data gathered from the support equipment like temperature, pressure, relative humidity, wind speed and direction. The data can also be used for technology improvements.
To keep up with evolving threats, the subway testbed needs to be enduring. This will continually enable assessment of current and emerging chemical and biodefense-related detection and identification technologies, as well as evaluation of rapid subway response and mitigation actions. The testbed will be cost-effective, as the cabinets can be used multiple times to test new technologies, providing a real-world environment to evaluate performance.
The sensor is aiming for bio-detection and confirmation within about two hours. Different types of bio-detection sensors will be installed inside the testbed. Some will collect samples on a filter and potentially analyse captured microscopic organisms, like the anthrax bacteria. While other sensors will look for distinctive characteristics of the organisms, like fluorescence, that indicate a potential hazard.
Regardless of their type, the sensors will be networked and monitored for alarms. The future goal for these technologies is to alarm immediately when a threat is suspected, so swift response decisions and actions can be taken. Multiple sensors using different physical principles to detect a threat would be ideal and provide higher confidence that something unusual may be happening.
The testbeds will also support mitigation testing. Train motion produces airflow that carries particulates, including released hazard pathogens. To diminish the spread of biohazardous plumes, researchers are looking at mitigation strategies like altering train position, speed and schedule, and particulate removal via filtration or liquid spray knockdown curtains and air curtains. If there is a bioterrorist attack, the sensors will send a signal to emergency operations centres triggering potential future mitigation strategies.
