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The National Academies

Transit IDEA J-04/IDEA 40 [Completed (IDEA)]

Counter-Terrorism Chemical Detector for Rail Transit Systems
[ TCRP J-04 (Innovations Deserving Exploratory Analysis--The Transit IDEA Program) ]

  Project Data
Staff Responsibility: Harvey Berlin

This project investigated the feasibility of a novel aerosol air collector and a chemical detector for subway cars and in subway stations. This research investigated an advanced sensor technology to rapidly collect and detect the release of toxic polar chemical species. Such polar molecules include the nerve agents, phosgene, chlorine, and nitrates indicative of explosive agents, to name a few. Dr. John Fenn of Virginia Commonwealth University conceived the aerosol collector concept. He is the 2002 Nobel Prize for Chemistry winner and a consultant on this Transit IDEA project. New York City Transit (NYCT) participated in this project.

The Transit System Chemical Detection Challenge

The most significant challenge for the successful integration of advanced sensor technologies into a subway system is the need to sample, concentrate, and analyze the local atmospheric conditions in real time. Most available field-portable sensing technologies provide detection thresholds that are not ideal for the highly dynamic conditions in a transit system itself. Furthermore, due to atmospheric dilution of chemical and biological signatures, point detection systems are often inadequate without significant sampling and pre-concentration in the local environment. Typically, air circulators entrain large volumes of air, which is then filtered and sampled before being analyzed for the presence of contaminants. However, the air samplers and pre-concentrators developed to date are very bulky and power consuming for use in an economical and small system.

The air sampling or entrainment of chemical particles using the electrospray ionization (ESI) technology is based on research by Dr. John Fenn. The ESI sampler offers a unique and unprecedented combination of performance parameters including low power, lightweight and high sampling efficiency over an enormous range of particle sizes from molecules to microscale particulates. It is believed that a suitable sensor suite for chemical agents may include specialized molecularly imprinted polymers (MIPs) and/or surface acoustic wave devices (SAWs) combined with the aerosol collector. It is expected that this would be capable of detection needed for trace chemical species such Sarin, VX, other nerve agents, and various explosives.

Figure 1

Investigation
This project included the following objectives:
¡ Identify and prioritize chemical agents that could be threats to subway systems;
¡ Identify mechanisms for delivering selected threats to rolling stock, stations, tunnels, passenger entry and exit points, ventilation points, etc.;
¡ Define initial ESI collector-detector system parameters using estimates of the threat, delivery mechanisms, airflow patterns, telemetry, and transmission information;
¡ Design a proof-of-concept demonstrator ESI collector-detector system;
¡ Perform laboratory controlled tests of the ESI proof-of-concept design;
¡ Identify design changes subsequent to initial testing; and
¡ Prepare and deliver a report of the results.
The project analytically verified the principals of operation and performance.
Product Payoff Potential
If a reliable chemical detector could be deployed on transit rolling stock and in subway transit stations it could assist in mitigating the effects of a terrorist release of chemical agents. Detection of dipicolinic acid from Anthrax using MIPs has been successfully demonstrated by colleagues at Virginia Commonwealth University under U.S. Army funding support, and is planned to be combined with the electrospray collector technology.
Product Transfer

The investigators have transitioned other applied research into manufactured products in ambient gas monitors for industrial and medical applications.

The final report for this IDEA project can be found at:
http://www.trb.org/studies/idea/finalreports/transit/Transit40_Final_Report.pdf.

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