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Digital signs around Brookline are collecting data from your phone as you walk by

A Soofa sign in Brookline Village. Photo by River Simard
March 22, 2024

You may have seen the electronic Soofa signs scattered around big intersections in Brookline. But did you know they’re doing more than just providing information? They’re collecting data from your cell phone.

Throughout Brookline, there are dozens of the seven-foot electronic ink signs, which resemble an oversized Kindle, dispersed on the sidewalks. The signs display black-and-white messages, such as the town’s official schedule, advertisements for Brookline businesses, bus schedules, and current weather.

The digital signs installed by the Cambridge startup Soofa, have a hidden feature unknown to most who pass them: collecting data from people’s phones to count the number of pedestrians who walk by, and then sharing that information with the town.

Soofa says the company does not pull in any personal data from the phones, but a privacy expert with the ACLU told Brookline.News that the practice is troubling.

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Here’s how Soofa says the process works: When a phone has wifi searching enabled, it is constantly sending out signals to attempt to connect to a network. According to the Soofa website, when a phone actively searching for a wifi signal comes within 15 feet of a Soofa sign, the signal that the phone sends out connects to Soofa’s internal network. The sign then collects the phone’s Media Access Control (MAC) address, a series of numbers that identifies devices on networks.

Once the MAC is collected, the sign encrypts the address to provide anonymity to the device. Then the sign stores the address and length of session time that the device spent connected with the sign. After the memory of the sign reaches capacity, the data set is collected by the company, deleted from the sign’s internal memory, and broken up into hour-long sections of data to determine high foot traffic areas by sessions per hour. The signs also collect IP addresses.

“It doesn’t take any privacy data, it’s like a giant digital clicker. We can’t see what the people are doing, what the demographic is, where they come from, or anything like that. But we do share the information with the town of Brookline,” explained Soofa representative Daniel West Cohen during an October Select Board meeting.

Brookline residents and visitors are not able to opt out of this data collection. To avoid data collection from Soofa signs, they would either need to turn off their phone’s wifi detection and Bluetooth or avoid the signs as a whole.

Kade Crockford, director of the Technology for Liberty Program at the ACLU of Massachusetts, said that the data collection is “perfectly legal” but problematic.

“IP information can be quite sensitive, depending on how much is collected, and how it’s used, and I think people in Brookline are right to be concerned about the degree to which companies that maybe they’ve never even heard of, are collecting information, that documents where those residents went in physical space, and when, without their knowledge or consent,” Crockford said in an interview.

ACLU Massachusetts has worked with several state legislators to propose a law that would restrict data collection such as Soofa’s.

While Soofa does provide information to the town of Brookline, as a private company, it owns the data that is being collected. When Brookline.News asked the company about their data collection process and what the data showed, a spokesperson referred the query to the town of Brookline. Assistant town administrator Devon Fields, who led the implementation of the program before her recent departure from the position, did not respond for a request for comment.

The town’s transportation division previously had an employee who worked directly with Soofa regarding data collection, but they left the department more than a year ago and have not been replaced. Since the employee left the position, the department has not been actively using information collected by the boards, according to Brookline transportation engineer Sam Downes.

“I’ve never heard anyone cite useful data, you know, useful to the rest of us, that resulted from the Soofa signs being located in various locations,” said Brookline select board Vice-Chair John VanScoyoc in an interview with Brookline.News. He elaborated that the data being collected does not offer any new perspective that couldn’t be easily observed.

Cohen argued that the importance of this data collection is to communicate with small businesses and provide insights based on pedestrian traffic. He provided examples such as helping businesses adjust their hours when more pedestrians are in an area.

Soofa is currently under contract with the town of Brookline, until the fall of 2025.

This story was produced in collaboration with the Reinventing Journalism course at Brandeis University, taught by Professor Neil Swidey, with mentoring for student journalists by Brookline.News steering committee co-chair Ellen Clegg and editor Sam Mintz.