As cities incorporate digital technologies into their landscapes, they face the challenge of informing people of the many sensors, cameras, and other smart technologies that surround them. Few people have the patience to read through the lengthy privacy notice on a website or smartphone app. So how can a city let them know how they’re being monitored?

Sidewalk Labs, the Google sister company that applies technology to urban problems, is taking a shot. Through a project called Digital Transparency in the Public Realm, or DTPR, the company is demonstrating a set of icons, to be displayed in public spaces, that shows where and what kinds of data are being collected. The icons are being tested as part Sidewalk Labs’ flagship project in Toronto, where it plans to redevelop a 12-acre stretch of the city’s waterfront. The signs would be displayed at each location where data would be collected—streets, parks, businesses, and courtyards.

Data collection is a core feature of the project, called Sidewalk Toronto, and the source of much of the controversy surrounding it. In 2017, Waterfront Toronto, the organization in charge of administering the redevelopment of the city’s eastern waterfront, awarded Sidewalk Labs the contract to develop the waterfront site. The project has ambitious goals: It says it could create 44,000 direct jobs by 2040 and has the potential to be the largest “climate-positive” community—removing more CO2 from the atmosphere than it produces—in North America. It will make use of new urban technology like modular street pavers and underground freight delivery. Sensors, cameras, and Wi-Fi hotspots will monitor and control traffic flows, building temperature, and crosswalk signals.

All that monitoring raises inevitable concerns about privacy, which Sidewalk aims to address—at least partly—by posting signs in the places where data is being collected.

The signs display a set of icons in the form of stackable hexagons, derived in part from a set of design rules developed by Google in 2014. Some describe the purpose for collecting the data (mobility, energy efficiency, or waste management, for example.) Others refer to the type of data that’s collected, such as photos, air quality, or sound. When the data is identifiable, meaning it can be associated with a person, the hexagon is yellow. When the information is stripped of personal identifiers, the hexagon is blue.

There’s also an icon with a QR code that users can scan to get additional details online, including how the data is processed, stored, and can be accessed. Yet another hexagon conveys information about the entity that’s collecting data. The signage is currently being displayed at 307, Sidewalk Labs’ demonstration space and headquarters in Toronto.

“We strongly believe that people should know how and why data is being collected and used in the public realm,” writes Jacqueline Lu, Sidewalk Labs’ director of digital integration, on the company’s Medium blog. “And we also believe that design and technology can meaningfully facilitate this understanding.

Still, privacy advocates say, the signs don’t go far enough in addressing their concerns. The Waterfront Toronto project already has attracted significant criticism for an overall lack of transparency and its data governance plans. Critics complain that the company has failed to adequately address why it is collecting the data in the first place, or how it intends to use the information.

“We’re not doing ourselves any service by simply putting out more notifications that data is being collected here. It’s just going to become more noise,” says Iben Falconer, a director at the urban design firm Gehl. “If we truly care about digital literacy and digital privacy, then we need to actually let people become part of that process.”

In tests of the prototypes, potential users have complained that the icon system is too complicated—one sensor that collects identifiable data requires a minimum of four icons and two colors, a number that increases if multiple types of data are being collected. “They said, ‘This is too complex, I don’t need to know all this stuff,’” says Patrick Keenan, who’s a principal designer at Sidewalk Labs. “And it’s literally four icons.”