The technology is vapourware. And even if it could be made to work, it would inevitably lead to intrusive police behavior, and traffic jams for riders as they pass through the security theater:
Less than a week after a man detonated a pipe bomb strapped to his chest in a crowded subway corridor in Manhattan, Senator Chuck Schumer urged the federal government on Sunday to speed up the rollout of a technology that can detect concealed explosives in crowded areas.
Since 2004, the Transportation Security Administration has been testing machines that can detect whether a person is concealing an improvised explosive device in crowded mass transit environments. Mr. Schumer called on the agency to speed up the tests and deploy the machines in New York City subways, bus stations and airports.
It is worth pointing out that New York has actually had two recent terrorist attacks on transportation facilities. The other attack, which Schumer failed to mention, involved a homicidal truck driver who killed 8 cyclists on a bike path. Fixing the dangers on bike paths is easy and uses proven technology; i.e. bollards, curbs, k-rail, etc. But whereas Schumer is promising “unlimited” funding for vaporware bomb detectors, he seems to have little interest in protecting users of sidewalks and pathways.