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The Underground Movement to Map Subterranean Chicago

Cities often don’t know where all their pipes and cables are. This new digital platform could solve that.

Repairs to a broken water main reveals the jumble of pipes and lines between city streets. (Matt Rourke/AP Images)

Every 60 seconds, Americans strike an underground pipe, according to estimates. Careless homeowners and lazy utility workers are partly to blame, but so are outdated, inaccurate, or simply nonexistent records. Subsurface America is poorly mapped. Case in point: Downtown streets in Chicago were closed for an afternoon this summer after construction workers hit a gas line and caused an explosion. Crews thought the pipe was out of service, but it still contained gas.

No one was injured, but such errors can result in tragedy. Likewise, when water mains and emergency service lines are struck, residents suffer inconvenience or worse, while cities, utilities, and construction firms lose time and money—all for a lack of a good underground map.

As part of its ongoing efforts to join the ranks of “smart” cities, Chicago is undertaking a block-by-block effort to map its subterranean side, working with a local technology strategy firm, City Digital, that’s devised a clever mapping platform that can gather and visualize the precise location of crucial underground infrastructure.

The idea takes advantage of recent advances in digital mapping: As local engineering firms and utilities open holes in streets or sidewalks, workers simply take a simple digital snapshot of the tangle of pipes and wires underneath. The image is then scanned into the mapping platform, which extracts key data points from it: namely, the depth, height, and width of the pipes in the photo. That 3-D data is layered onto a digital map of Chicago’s streets. Over time, as more holes are punched open and more images get translated, the platform can extrapolate the layout of other underground areas that haven’t been ripped open. And with continuous refinement and reconfiguration, it can do so with increasing accuracy.

”It’s almost like we’re creating a videogame environment,” says Steve Fifita, the executive director of City Digital. “We start with one image, and then we map it to a digital rendition that has the right engineering parameters.”

Photos of underground assets are stitched together, transformed into 3D data points, then translated into a digital file. (City Digital)

So far, the platform remains in the testing phase. One prototype was used successfully at a construction zone last year, and soon an updated version will be deployed at a larger site in Chicago’s River North neighborhood. “That pilot is going to let us try to digitally map the whole block,” says Fifita. Eventually, his team hopes to extend the process to all of Chicago. If all goes successfully, the city will be able to store and utilize the map’s data—and charge local construction firms and utilities to access it. That could serve up savings in construction delays and water main breaks, potentially avoid needless tragedy, and provide a revenue stream to the city. Other towns that are just as much in the dark about their subterranean assets are keen to see how the pilot goes, Fifita says.

Current techniques for detecting buried infrastructure from street level, such as ground-penetrating radar systems and radio-detection units, aren’t as effective, and their accuracy depends a lot on the skill of the user. Plus, they only give isolated snapshots of what lies beneath: They don’t necessarily contribute to a comprehensive understanding of how a city’s underground networks fit together.

The mapping scheme is in keeping with Chicago’s other recent efforts to become "the most data-driven government in the world,” as Mayor Rahm Emanuel’s top-ranking tech official recently put it. Above ground, the federally funded “Array of Things” project is set to install some 500 sensor “nodes” around the city, tracking air quality, temperature, moisture levels, traffic movements, and noise. The resulting data will be open to researchers and the public for analysis and planning, as well as to corporate vendors developing tech-based solutions. Chicago also recently joined with Mastercard’s Global Cities Business Alliance, which will use consumer spending patterns to identify areas where digital technology can improve business transactions.

Noting that city leaders have been famously cozy with corporate partners, some critics have suggested that some of these “smart city” initiatives appear to benefit tech vendors more than Chicago residents. Others have raised privacy concerns about having the city wired head-to-toe with scanners and cameras—and who might ultimately profit from the information.

The structure by which the underground mapping project is being developed certainly stands to enrich the private sector. Chicago has an existing partnership with City Digital, which has brought together a number of other collaborators to build out the technology, including researchers at the University of Illinois, HBK Engineering, and tech consultants Accenture. With Chicago serving as a proving ground and first customer, developers plan to later sell the platform to other cities.

Given the error-laden way authorities currently figure out what’s going on down there, it could prove to be a smart investment.

About the Author

  • Laura Bliss
    Laura Bliss is a staff writer at CityLab. She writes about the environment, infrastructure, and cartography, among other topics.