The “Array of Things” Enters Chicago

By Rob Mitchum

The “Array of Things” team has begun the first phase of a groundbreaking urban sensing project, installing the first of an eventual 500 nodes on Chicago streets. By measuring data on air quality, climate, traffic and other urban features, these pilot nodes kick off an innovative partnership between the University of Chicago, Argonne National Laboratory and the City of Chicago to better understand, serve and improve cities.

Array of Things is designed as a “fitness tracker” for the city, collecting new streams of data on Chicago’s environment, infrastructure and activity. This hyper-local open data can help researchers, city officials and software developers study and address critical city challenges, such as preventing urban flooding, improving traffic safety and air quality and assessing the nature and impact of climate change.

In the first phase of the project, 50 nodes have been installed on traffic light poles in The Loop, Pilsen, Logan Square and along Lake Michigan. These nodes contain sensors for measuring air and surface temperature, barometric pressure, light, vibration, carbon monoxide, nitrogen dioxide, sulfur dioxide, ozone and ambient sound intensity. Two cameras collect data on vehicle and foot traffic, standing water, sky color and cloud cover. A total of 500 nodes will be installed across Chicago by the end of 2018, and additional nodes will be shared with cities across the United States and in countries such as England, Mexico and Taiwan.

“The University of Chicago has a long and flourishing tradition of scholarship that engages with urban life and makes a positive impact,” said Robert J. Zimmer, president of the university. “The Array of Things project advances these ideals by gathering a broad scope of data about the urban environment, in a form that researchers, policymakers and residents can use to develop innovative ways of improving our city and urban areas around the world.”

The Array of Things project is just one example of the advancements that are possible when the city, university and Argonne combine their diverse and complementary perspectives, experience and expertise,” said Argonne Director Peter B. Littlewood. “I’m excited to see the Array of Things fulfill its potential to help make Chicago cleaner, healthier and more livable, and I also look forward to future game-changing collaborations with our local partners.”

Initial node locations and data applications were determined based on interactions with community organizations and research groups. Eight nodes in Pilsen contain sensors for tracking air quality and its relationship with asthma and other diseases. Partnerships with the Chicago Loop Alliance and Vision Zero motivated studies of pedestrian and vehicle flow and traffic safety in The Loop neighborhood. And scientists at  the University of Chicago and Argonne chose locations along the lake and across the middle of Chicago that will allow for optimal measurements of features related to urban weather and climate change.

“The Array of Things is a community technology,” said Charlie Catlett, director of the Urban Center and Computation and Data at the University of Chicago and Argonne and the lead investigator of Array of Things. “It’s about creating new streams of data that help us understand and address the most critical urban challenges. Where we see an intersection of resident concerns, science interests and policymaker interest, that’s where we see opportunity for Array of Things deployment in Chicago.”

Array of Things will also support city efforts to provide smarter and proactive services using predictive analytics and data-driven policy. For example, by tracking the weather conditions leading up to flooding at intersections, city crews can respond more quickly to floods or make infrastructural changes that prevent standing water from accumulating. City departments could also use data on heavy truck traffic and air quality to make decisions about commercial routing that preserves clean air and safe roads in residential neighborhoods.

“It’s truly doing science in the city and out in the communities. We’ll be able to engage with community groups to help them make the data their own and figure out to use it to address the questions they have,” said Brenna Berman, Chief Information Officer of the City of Chicago. “You’re going to see community groups use this data to understand their communities and neighborhoods better as we all try to build a better life here in Chicago.”

Data collected by Array of Things nodes will be open, free and available to the public, researchers and developers. The project publishes data through the City of Chicago Data Portal, open data platform, and via application programming interfaces. As specified by the Array of Things privacy and governance policies, no personally identifiable information will be stored or released by sensor nodes.

For more information on Array of Things, or to suggest a future research question or node location, visit

Rob Mitchum Is a writer at the University of Chicago.