Excerpts of a Report from The Pursuit Management Task Force

Stopping Vehicles With Directed Energy

Source: Martin’s Page

Below are excerpts of a report from The Pursuit Management Task Force dealing with all aspects of stopping vehicles during chases involving law enforcement. I cut all the non energy related stuff out and left the parts detailing the use of radiative/directed energy devices.

Radiated electrical techniques fall into two main classes: radio frequency (RF)/microwave (MW) and ultrawideband (UWB)/electromagnetic pulse (EMP). Both types are totally electromagnetic, with no "hard" or inherently dangerous ionizing radiation (x-ray or nuclear) types being proposed or investigated at this time.

(Electromagnetic (EM) waves, however, still can be emitted to an unsafe degree if safe exposure standards are exceeded). RF/MW and UWB/EMP differ only in frequency range and pulse rise and fall times, leading to different frequency coverage or "content" in the pulse. RF/MW frequencies are generally considered to fall in the several hundred megahertz (MHz) to several hundred gigahertz (GHz) range, with the pulses or continuous waves (CW) usually considered "narrowband"; i.e., with a small range (less than 10 percent) around a single frequency.

UWB/EMP pulses, on the other hand, are very wideband or "ultra" wideband, containing a large range of frequencies in each pulse, but generally considered in the overall lower range up to 100 - 200 MHz. The frequency content leads to differences in how the electromagnetic waves "couple," or penetrate, the outer metal skin and the electronic engine control, ignition, or other electronics of the vehicle. High frequency or short wavelength EM waves couple better with the small electronic components within the vehicle’s electronic engine control boxes, but are highly attenuated when passing through metal joints and other ports-of-entry such as windows to reach those components. Long wavelength, low frequency EM waves, however, couple better with the larger metal structures, allowing less attenuation in penetrating a vehicle’s body, after which they cause "resonant" EM field buildups that, in turn, induce currents to flow in the electronic engine controls and their electronic components through their connecting cables or wires. The latter, low RF/MW, EM waves (i.e., less than a few GHz, such as those that power microwave ovens), appear to work better for most radiated engine-stopping techniques evaluated so far, but more testing remains before final conclusions can be reached.

The safety and effectiveness of all the currently proposed electrical methods, whether direct injection or radiated, were intensively investigated by the Army Research Laboratory (ARL) in partnership with the National Institute of Justice(NIJ). In their investigation, ARL utilized a number of target vehicles obtained from the Federal drug asset forfeiture program of the Immigration and Naturalization Service (INS) and U.S. Border Patrol (through the Chief of the U.S. Marshal’s Service) and some vehicles previously purchased by ARL. These vehicles were gasoline-powered commercial sedans, vans, and small trucks, made by most major U.S. and foreign carmakers, giving a good sample of the different electronic engine controls in current use around the world. During each participant’s test and evaluation EM field levels were measured by EM probes placed at various points both inside (at the driver’s and passenger’s positions) and outside the various test vehicles. The field levels measured were then compared with the Institute of Electrical and Electronic Engineers’ safety standards(the basis for the American National Standards Institute / Occupational Safety and Health Administration (ANSI/OSHA) standards). The results of this ARL/NIJ study, presented to NIJ as a separate report by the ARL, compared the relative safety and effectiveness of the various electrical techniques evaluated. The ARL’s report concludes with a recommendation for additional phases of testing on some of the technologies tested, including outdoor testing in simulated field conditions. The PMTF concurs with the ARL’s recommendation.

Electrical Systems

The Army Research Laboratory (ARL) in Adelphi, Maryland, conducted tests on electronic vehicle-stopper technologies concurrent with the work of the PMTF. Dr. Edward Scannell, director of the study, who also serves as a member of the PMTF, has kept the PMTF advised of the progress in testing. It appears, based upon the ARL testing, that electrical vehicle-stopping is a viable option, but much more research and development is required before a usable product emerges. The PMTF’s surveys showed strong support for electrical vehicle stoppers among members of the public and officers surveyed. The PMTF recommends that resources be allocated for additional testing and proof-of-principle demonstrations of electrical vehicle stoppers that, hopefully, will lead to a marketable product. One concern with the use of any electrical system is the potential for loss of vehicle systems that impact driver control (e.g., power steering and braking) and that occur when engines stop operating. Although this is often likened to running out of gas, it is nonetheless a potential liability concern.

Radiative Systems

Radiative electrical vehicle stoppers differ from their direct injection counterparts in that no actual contact between the vehicle and energy source is required. This, in theory, removes the necessity to place objects on the roadway in the path of a fleeing vehicle or to launch a projectile at it. The potential ability to stop a vehicle without actually contacting it greatly interests the PMTF. The PMTF is aware of prior research conducted by ARL on a high-power microwave vehicle stopper. Although not fully tested or developed, the system appeared to be able to disrupt electronic engine controls. Radiative systems would have the same impact upon the fleeing vehicle as their direct injection counterparts. Only the delivery system is significantly different. If target dwell times can be condensed and targeting itself enhanced to avoid collateral damage, such systems appear to have great potential at fixed-point locations. If portability could be enhanced by creating smaller and more lightweight systems, their use in typical police pursuits would be enhanced. Finally, if a device could be mounted on the front of a chase vehicle and pre-targeted for a distance directly in front of the chase vehicle, such a system could be most significant in minimizing the risks associated with pursuits. Difficulties encountered with radiative vehicle stoppers are significant, however. They include problems associated with collateral impact on other electronic devices in common use, and requirements for hardening (or shielding) the deployment platform from its effects. Nonetheless, radiative systems appear to have significant promise for use in typical police pursuits, and the PMTF recommends additional research and testing for such devices.

Another concept for an electrical vehicle stopper came to the attention of the PMTF in late June 1997. A company proposed a plasma beam technology concept that could have applications for stopping fleeing vehicles. In theory, high-voltage RF currents could be directed at a fleeing vehicle, resulting in disruption or destruction of electronic components. The potential for enhanced target specificity of such a system, coupled with the potential for deployment from a chase vehicle platform, interests the PMTF. This technology is in its early conceptual state and requires significant work prior to prototype testing. Pending proof-of-concept demonstration, the PMTF does not yet have the requisite information to make a specific recommendation regarding this concept.

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