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Construction Corner: Array of Things a ‘Fitbit’ assessing Chicago’s performance

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Cities are complicated things.

They’re the economic engines of most nations. They’re where the largest percentage of our populations live. They’re responsible for a large percentage of greenhouse gas emissions.

But there is a lot about the urban dynamic we don’t understand. It’s especially tough in big cities.

Now though, in the age of "big data," we’re getting serious about smart cities. That means sensors measuring all kinds of things, giving new insights into stuff we thought we understood, like how energy is used in large buildings.

Chicago, with 2.7-million people packed into about 600 square kilometres, is pretty typical. It has the problems you would expect in a city that size. There’s a lot happening there and people know intuitively that they’re all connected. But how?

So the city launched a project last autumn that will attempt to gather the data needed to make intelligent decisions.

They’re calling it the Array of Things (AoT) and it will be rolled out during the rest of this year and next. Think of it as a "fitness tracker," a Fitbit for the city.

The AoT will be made up of 500 "nodes" scattered around the city. Each of them will contain a dozen or more sensors that will send data to a central server. The sensors will measure things like air and surface temperature, barometric pressure, light, vibration, carbon monoxide, nitrogen dioxide, sulfur dioxide, ozone, ambient sound intensity and more. As well, each node will have two cameras collecting data on vehicle and foot traffic, standing water, sky colour and cloud cover.

The nodes are not intrusive. Imagine four hardhats stacked one atop the other. They are being mounted on traffic poles. They cost between $1,200 and $1,600 each. The price varies because there is some variation in how they are equipped.

One area has a highway running through it, so air quality, noise and vibration are likely to be different from quiet residential areas that are well removed from highways.

The nodes will be able to provide measurements of micro-climate in different areas of the city so that residents can get up-to-date, high-resolution block-by-block weather and climate information.

The city is going to end up with an awful lot of data. What will it do with it?

People running the project tell us that the data will be used for things like traffic co-ordination, air quality warnings and flood detection. They also expect to be able to address some tough multidisciplinary questions. What, for example, are the correlations between weather, noise, pollution, traffic and social trends?

The data collected will be stripped of anything that might identify anyone. Then it will be posted on a website where it will be available free for everyone. For example, the city expects that it will be used by developers to create new sensing devices, some of which might find their way into some of the AoT nodes.

The project is funded by a US$3.1-million grant from the country’s National Science Foundation, with additional investments from the Argonne National Laboratory and the Chicago Innovation Exchange. The city is paying for installation of the nodes and the electricity to power them.

If you’ve been reading much about the Internet of Things (IoT), you might think that’s all the AoT is. You’d be right. But a name was needed to differentiate between Chicago’s system and a generic IoT system.

The AoT has formed partnerships with universities in nine North American and global cities to collect data. Those involved are New York City, Seattle, Portland and Atlanta in the U.S., Newcastle, Glasgow and Bristol in the United Kingdom, plus Mexico City and Amsterdam.

Each of those cities will receive five to 10 nodes for collecting data on their local environment and infrastructure.

The big payoff, of course, is that the system will permit public officials to make decisions based on evidence.

Korky Koroluk is an Ottawa-based freelance writer. Send comments to

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