In April 2022, New York City Mayor Eric Adams had an idea for improving transit security: Install artificial intelligence-driven “weapons detectors” in front of subway turnstiles.

“There’s a new method that can detect weapons that are not the traditional metal detectors that you see at airports,” Adams, just weeks into his tenure, said. “You don’t even realize it’s there.”

But the detectors Adams was talking about can be inaccurate, misidentifying an array of everyday objects, from cell phones to umbrellas, as threats. When the devices ping an item, the person carrying it must be routed to more conventional secondary screening, which can cause significant delays. They’re mostly used at event venues, and experts foresaw chaos if officials implemented the tech on public transit.

“Expect delays, expect secondary screening, expect frustration, and expect to miss your train from time to time,” said the CEO of one company that makes the detectors.

On Wednesday, two years after floating his idea, Adams announced that he was finally deploying the weapons detectors in the subway system. Read New York Focus’s prescient investigation into the embattled company he’s signed with.