For now, the agency has given up on scanner technology aimed at detecting threatening footwear.
The Transportation Security Administration has abandoned a project to buy shoe-scanning devices that would allow airline passengers to waltz through security checkpoints without removing their Uggs and Nikes.
The government could not find a tool in the marketplace that met its requirements, TSA officials said this week. Possible reasons contracting experts gave for why TSA came up empty: the devices offered were too expensive, unreliable or exceeded radiation limits.
"The shoe-scanning technology solicitation did not result in any viable systems that meet TSA's technical or operational needs," said Lisa Farbstein, a spokeswoman for TSA, part of the Homeland Security Department. "While the procurement was canceled, TSA looks forward to continuing to work with its partners within DHS and industry to identify the best technologies and solutions for the security checkpoint."
Travelers bemoan the process of taking shoes on and off and walking around barefoot, but they have not been too keen on submitting their appendages to X-rays either. Radiation fears about the current crop of body scanners, however, apparently pale in comparison to the uproar last century over X-ray exposure from shoe-fitting machines. Retailers in the 1930s began measuring customers' feet with a device called a shoe-fitting fluoroscope until safety concerns in the 1950s led to their eventual extinction.
The request for bids that TSA issued last spring called for a shoe-scanning machine that would emit at most 0.5 milliroentgen units of radiation per hour. The shoe-fitting contraptions used from the 1930s into the 1950s subjected customers to 4 milliroentgens per hour -- eight times as much as the present day limit. "When you put your feet in a shoe-fitting fluoroscope, you were effectively standing on top of the X-ray tube," said a report by the Oak Ridge Associated Universities, an academic consortium. "The only 'shielding' between your feet and the tube was a 1-millimeter thick aluminum filter."
The 2011 solicitation did not require that the proposed technology take any particular form, such as a wand or a stationary platform. The goal was to deploy some type of technology that would effectively flag explosives "without requiring passengers to remove their footwear," the notice stated.
The airport shoe removal rule kicked in shortly after would-be bomber Richard Reid tried igniting the explosive-laden shoes he was wearing in December 2001. But now, "the removal of footwear takes time, reduces the efficiency of the checkpoint, creates safety concerns with footwear removal and contributes to passenger dissatisfaction," TSA officials acknowledged in the request for proposals.
Recently, TSA instituted what officials call "common-sense" policies that let select frequent fliers and children up to age 12 wear their shoes through checkpoints.
Ray Bjorklund, chief knowledge officer at research firm Deltek, said a variety of factors could have prompted TSA to pull the purchase, including the possibility of creating even longer lines. The functional specifications cited in the solicitation describe a system that can "increase overall operational throughput" by shortening the amount of time it takes for officers to clear a passenger.
He speculated that TSA's reference to working with partners inside Homeland Security could mean that another DHS office, perhaps the Homeland Security Advanced Research Projects Agency or the department's Science and Technology Directorate, "may have already started down a similar path, one that is more promising than the one TSA was pursuing."