Scanning Crowds for Bombs

The airport checkpoint is a linchpin of aviation security, but one of its unintended consequences imparts vulnerability: the long, weaving line of travelers who await screening. The lines present suicide bombers with a potential target that is common not only to airports but also to public events where masses must pass through security screening.

Passive millimeter wave scanners can spot suspicious objects under clothes, and someday, laser spectrometers may spot explosive residue on clothing yards away. Both technologies still, however, would require that people pass through choke points, as these technologies can only scan one person at a time.

With these threats in mind, the Air Force Research Laboratory (AFRL) at Wright-Patterson Air Force Base, Ohio, pitted students from rival colleges against one another in a competition to see which school could better detect simple improvised explosive devices (IEDs) across large areas and groups.

The winning entry, fielded by students from the University of Michigan, relied on sensors linked by a wireless network, with software that processed data from the sensors to spot potential threats. The concept holds the promise of scanning large areas and crowds for explosive threats.

The AFRL based the competition’s scenario in part on an historical event—the 1996 Olympic Park bombing in Atlanta, where Eric Rudolph detonated a fairly rudimentary IED—a pipe bomb composed primarily of metal.