Following the Sunset Park subway shooting, Mayor Eric Adams floated the idea of adding “something like metal detectors” to station entrances to keep guns out of trains. The comment created immediate pushback, as some questioned the feasibility of installing metal detectors at every turnstile of the city’s 472 stations.
Any New Yorker who has traveled by plane knows that standard metal detectors are slow. Nobody wants to put their phone in a small trash can while they rush to their place of work. A spokesperson for the mayor later clarified that Adams did not refer to airport type detectors because “he knows it’s not practical”.
Adams, instead, was referring to a new-age scanner that millions of New Yorkers already use every year. City Hall confirmed to Gothamist that one of the detectors under investigation is made by Evolv Technology, a security company based in Waltham, Massachusetts.
Like other metal detectors, Evolv uses an array of magnetic sensors – 50 in total – to spot when someone is carrying metal. But these sensors are linked to machine learning algorithms, a type of artificial intelligence, so the company can not only spot a metallic object, but also determine its density or shape, like the barrel of a gun. fire.
Evolv officials say their main goal is to prevent threats of mass casualties against a crowd by detecting weapons such as guns, large knives and bombs.
“We wrote all the signatures for all the weapons,” Evolv CEO Peter George told Gothamist. “The magic lies in the ability to distinguish between a phone and a gun.”
When the scanner receives a hit, the system takes a picture of the person and a red 3D box hovers over where the suspicious object might be. The image also allows a nearby security guard to pull the person out of a crowd. This automated setup allows for a higher volume of foot traffic. The company says its base model – the Evolv Express – can check around 3,600 people per hour, which it says is 10 times faster than traditional metal detectors.
George told Gothamist that the company’s devices have screened 11 million New Yorkers since they were rolled out to the city three years ago, a huge toll given the pandemic has hampered public gatherings. Their deployment includes places of worship, museums, performing arts venues and popular tourist sites in New York, he said.
Company documents indicate that Evolv scanners are already in use by Lincoln Center, New York-Presbyterian Hospital, Metropolitan Museum of Art, American Museum of Natural History and MoMA. City Hall said Citi Field also relies on technology, although a spokesperson for the New York Mets referred all questions about it to the mayor’s office.
“Of course, any technology that could possibly be used in the subways would be coordinated with the governor’s office and the MTA before being used and should complement the existing technology already present in our subways,” Fabien Levy, press secretary to the mayor , says in an email to Gothamist
But New York’s public transit system is no museum when it comes to the number of people who pass through it. On Tuesday, when the 36th Street shooting took place, the subway was carrying 3 million riders, and that massive volume is half of what was happening before the pandemic.
Privacy advocates and security watchdogs worry that installing this kind of mass surveillance technology on the subway could inadvertently sweep up unarmed people.
“It also touts the combination of this object technology with CCTV and video analytics, including facial recognition,” said Donna Lieberman, executive director of the New York Civil Liberties Union, “which is also notoriously riddled with mistakes, especially regarding Black and brown people.
Would these weapon detectors work for the NYC subway?
That’s the question the mayor’s office wants to answer before pushing the MTA to pursue the technology.
As Gotham Gazette reported last month, New York City Health + Hospitals is piloting Evolv scanners at Jacobi Medical Center in the Bronx after a shooting that occurred there in January. City hall said it wanted to analyze how the pilot program worked before deciding whether or not to go ahead.
“Mayor Adams has made it clear that public safety is his top priority, and he is prepared to test and analyze many forms of technology in a legal and responsible manner to protect New Yorkers,” Levy said.
Evolv detectors operate on different sensitivity settings, and this setting helps detect whether metal objects are spotted at higher and lower rates. But gun barrels look like other tubular objects New Yorkers might take to museums or schools, like umbrellas.
“What Evolv is able to do is they have the ability to differentiate certain objects from being benign or being of genuine concern,” said Donald Maye, a former Army officer. who is head of operations at IPVM, a research company specializing in the video surveillance and security sector.
But Maye wants the company to be more transparent about its weaknesses, namely the potential for false positives. The Evolv detectors were recently reviewed by independent investigators from the University of Southern Mississippi, which operates the National Center for Spectator Sports Safety and Security (NCS4). This center conducts field exercises to see if emerging security technologies meet federal standards.
The center gave Evolv a high overall score for weapons detection and false alarm avoidance, beating out competitor Patriot One Technologies. (Patriot One’s scanners reportedly had a problem with creating false alerts with Apple Watches and AirPods). But NCS4 reviewers only released a partial 25-page report for Evolv, while Patriot One’s review is more detailed at 61 pages. Evolv’s full report is only available upon request from the company “subject to confidentiality to qualified security professionals directly responsible for deploying Evolv Express.”
“Our contention, as an organization reporting on this, is that transparency is what’s important, and this information should be made public,” Maye said. “The public, who are often the subject of this technology, should know what its true capabilities are.”
Even though Evolv detectors can distinguish some benign objects — umbrellas, strollers, glasses cases — from weapons, an eastern Illinois school district reported last fall that the system was having trouble with Google Chromebook.
“Chromebooks have tubular-shaped metal hinges,” Maye said. “So at certain sensitivity settings, we know Chromebooks will alert like a gun.”
Maye added that the school district used a workaround in which students held Chromebooks above their heads or in front of them as they passed through the scanner. IPVM has written a number of critical reviews of Evolv detectors — to the point where the two groups no longer communicate with each other, Maye said.
No technology is foolproof, and since Evolv uses machine learning algorithms, the system is designed to get smarter over time to reduce false flags. George, the CEO of Evolv, also said the company recommends that their systems be monitored by security guards so that real threats can be checked.
In the case of the New York City subway, that means police would have to be near every turnstile in all five boroughs. Screening 3,600 people per hour, single Evolv detectors could potentially manage foot traffic traversing the subway system. Times Square, the city’s busiest station, currently sees around 74,000 entries per day, or an average of 3,000 travelers per hour. (Some times, like rush hour, obviously see a lot more people.)
The placement of detectors is another major consideration. Earlier this year, a person stabbed several staff members at MoMA’s reception desk while Evolv detectors were on hand. That’s because the scanners weren’t placed right behind the doors, but rather a few feet back. George said the company was working on a version of the device that could be integrated into doors and interior jams.
NYCLU’s Lieberman also questioned whether mass surveillance can really get to the roots of crime.
“The COVID pandemic has exposed so many gaping holes in our social safety net,” she said. “The lack of affordable housing at all levels, the lack of supportive housing for people in distress and with mental illness.”
Gothamist asked the MTA if it was considering Evolv Technology or similar weapons detectors, and a spokesperson pointed to comments made Thursday by Chairman Janno Lieber.
“If there are technologies that can make everyone feel safe, make it even more desirable to share what is our birthright as New Yorkers (the subway and public transit), I totally agree,” he said. “I just don’t know enough about how they would work on the subway. All I’ve said so far is that I’m all for every thoughtful idea that might work.