In 2013, we started with an idea: could we use new technology to provide much more detailed measurements of cities? At Argonne National Laboratory and the University of Chicago, we designed a sensor platform that could withstand the elements in urban environments, and asked dozens of scientists at other universities and research laboratories for the types of data they would find useful. In 2015, we proposed an experiment — to put hundreds of these devices into Chicago — the National Science Foundation provided funding, and the Array of Things project was born.

The project was and is envisioned as a new kind of community technology — an urban sensing project designed for communities, educators, students, policymakers, and residents to better understand cities. Originally, we expected to install a network of environmental sensors in Chicago alone. But once we got started we began to hear from other research groups and cities expressing interest in using our technology in their cities.

At the same time, further interactions with science communities refined the specifications for exactly what we would measure, and this included the concept of using computer vision to “measure” things like vehicle or pedestrian flow, or flooding. Today we have partners and associated deployments of AoT nodes not only in Chicago, but also in cities around the country, and soon, globally.

This spring, five years after we first imagined an urban-scale measurement instrument, Array of Things is hitting many significant milestones. Here’s what we’ve been up to:

The first one hundred nodes in Chicago

Last week, electricians from the Chicago Department of Transportation (CDOT) installed the Array of Thing’s 100th node at the intersection of Western Avenue and Addison Street. You can find nodes installed all across the city: near Soldier Field, on The 606, in neighborhoods from Little Village to Garfield Park to Edgewater. Currently, there’s a node within two kilometers of 80 percent of the Chicago population. And we still have many more to install — the plan is to deploy hundreds of additional nodes in the coming months.

It is an enormous effort to deploy an experimental technology on this scale, and our path to 100 nodes led to important insights regarding urban-scale scientific instrumentation and key partnerships with the City of Chicago’s Department of Innovation and Technology and CDOT. Unlike traditional sensor networks that use very rugged, pre-programmed microprocessors, AoT nodes are remotely programmable with fully functional, and more delicate, computers. AoT nodes thus include custom electronics to increase reliability, for example by putting the delicate computers into hibernation if the temperature is too high or if moisture is detected.

This resilience proved essential in the first test deployments of late 2016 when moisture build-up in some of the units caused them to go “off the air” for hours or days at a time over their first winter. Without the resilience features, electronics in the units would have simply burned out. Instead, they just went offline until the moisture evaporated, then rebooted and continued to take measurements.

Updates to the housing of the nodes addressed the condensation issues, as tested through this past winter, and the next big test will be extreme heat in the coming summer months. We anticipate the possibility of brief outages on sunny August afternoons, but our resilience electronics will protect the systems from burning out permanently. These experiments and continuous improvements underscore the nature of the project — Array of Things is a science project, first and foremost.

Array of Things data is now available

From the beginning, our mission with Array of Things was to make data collected by the sensor nodes openly, publicly, and freely available. But before that could happen, we wanted to make sure we had enough nodes to provide meaningful geographic coverage and, moreover, that the data could be scientifically evaluated, particularly given that many of the sensors use new technologies that have not previously been installed at such scale. We’re happy to announce that the first batch of data is now available for use by the public.

At our beta site, users can download temperature, humidity, and barometric pressure data from nodes across our growing network. These readings provide hyper-local looks at environmental data over the last several months. Currently, you can download this data from individual nodes as a (very large) csv file, but we are working on integrating the data into Plenario, a database system that supports both the City’s OpenGrid data portal and our own browser-based tool for finding and visualizing data.

The currently available data come from just a subset of the sensors installed in AoT nodes; we are also collecting data on other conditions, such as vibration, light and sound levels, and magnetic field, which should be available in the coming weeks. Additionally, we are measuring key air pollutants using a new generation of sensor technology. For these measurements, calibration and testing is necessary before we can start releasing the their data. To fully evaluate these sensors, we have deployed test nodes with air quality sensors at an Illinois EPA testing facility on the South Side, so that we can test the accuracy of these readings against the industry standard measurements.

Later this year, we are also hoping to begin to report on measurements that are derived from image processing. We have been experimenting with algorithms for detecting flooding, as well as for reporting pedestrian and vehicle counts at intervals of several minutes, creating a measure of pedestrian and vehicle flows over time. All of these measurements are in line with an extensive set of privacy policies and procedures that are documented at our website.

We’ll announce new data releases on the Array of Things website and social media, and welcome community feedback on the initial release. In the coming months, we will be seeking input from and collaboration with residents at community events to review AoT data and better understand how it can be presented in a way that provides the most value. These events will be announced on our website and social media soon.

Lane of Things starts its third year, expands.

The Array of Things project was conceived not just as a science project, but as a project that we hoped would inspire Chicago’s youth about the potential for using science and technology for positive impact on their neighborhoods. Lane of Things, our high school educational program based at Lane Tech College Prep, is currently in its third year of operations.

Executed in partnership with the School of the Art Institute of Chicago and run by Douglas Pancoast, Robb Drinkwater, Kate Kusiak Galvin, Satya Mark Basu, Jeff Solin, and Dan Law, Lane of Things is an eight-week curriculum that uses similar technologies to AoT as a platform to help students learn about programming, data science, digital fabrication, and additional computer science concepts. This year, the students installed their sensors in and around Wrigley Field. You can read more about the project from the Chicago Tribune.

With support from Motorola Solutions Foundation, Lane of Things will also be expanding to more schools in Chicago this year. We’re formalizing the curriculum and holding a professional development workshop for Chicago Public Schools teachers this summer, so that students across the city can receive hands-on experience with sensor technology and science through building their own version of the Array of Things project.

It’s been an exciting year for Array of Things, and we’re just getting started. For the latest news, visit our website and follow us on Twitter.

- Charlie Catlett, Director, Urban Center for Computation and Data