Six Tunnels Hidden Under Chicago's Loop
Karri DeSelm works in the JW Marriott Building, on the corner of LaSalle and Adams in downtown Chicago. Her building, the last designed by famed architect Daniel Burnham, was completed in 1914, and underwent major renovations two years ago. Karri says that at the time, her boss told her that she had been down deep into the building’s basement, where she had seen the entrance to a secret tunnel that ran underneath the Loop. That got Karri wondering: “I have heard there is a network of layered tunnels under the city. Is this true, and if so, what was the purpose of the tunnels when they were designed and built?”For starters, it’s true — there are many tunnels underneath the Loop. We found no fewer than six different sets of tunnels, including the tunnels connected to Karri’s building. Each of the tunnels we found was at some point, or continues to be, a critical part of Chicago’s infrastructure. The city would be lost without these tunnels. Sometimes they’re hidden, and sometimes they’re just overlooked, taken for granted by the people who walk above them. But trust us — 2.8 million people would notice the tunnels’ absence because they’d have no reliable source of clean tap water, no flood control and no crosstown “L” service in the Loop. And the tunnels that aren’t still in use are more than just odd architectural remnants or historical curiosities. They may be obscured from sight and from memory (or even sealed off), but they’re still an important part of the city’s built environment. As one source put it, we ignore the tunnels at our own peril. When we erect new buildings downtown, we do so in a densely layered maze of infrastructure, both old and new. To help wrap our heads around Karri’s question, we worked with Erik N. Rodriguez of The Illustrated Press. Based on our reporting, he created the graphic above, which shows six different kinds of tunnels, how deep underground they are and how they’re situated relative to one another. Note, though, that the drawing is a composite; it shows what can be found at different depths across the Loop, but not necessarily beneath any single street address.
1. The Pedway, Short for “pedestrian walkway,” this maze-like system of semi-public hallways connects the basements of more than 50 Loop buildings, including municipal buildings like City Hall and the Thompson Center, shopping centers like Macy’s and Block 37, and a few newer residential buildings, like the hypermodern Aqua tower. The Pedway also snakes through two CTA stations.
2. CTA tunnels File these tunnels under those you probably take for granted. Although the city prides itself on its extensive network of elevated trains, two downtown subway tunnels also move commuters through the Loop. These tunnels are now owned and operated by the CTA, and in 2012, the combined “L” stops inside the two tunnels served an average of 82,343 passengers every weekday.
3. Freight tunnelsOf all the tunnels under the Loop, the 60 miles of freight tunnels 40 feet underground are the most extensive. They also happen to be unique to Chicago.
4. Cable car tunnelsBetween 1882 and 1906 it was the cable car network, not the “L,” that served as Chicago’s main form of public transit. In fact, Chicago’s cable car system was once the largest and most profitable of its kind. But both means of transit ultimately fell out of use. When the “L” became ascendant the cable car tunnels were abandoned and sealed. They’re still there, though, and there’s plenty more to read about their remnants.
5. Water tunnels In 1867 Chicago built an intake crib two miles out in Lake Michigan to collect fresh drinking water for the growing city. Earlier efforts to collect water closer to shore had failed. If this fact inspires a big yawn from you, consider that at this point the city was still dumping sewage into the Chicago River, which fed directly into the lake. But the city is tight-lipped about what other parts of this infrastructure remain in use. We wanted to know where the remaining tunnels are located and how deep underground they are, but the Department of Water Management denied our request.
6. The Deep Tunnel The Deep Tunnel is rarely referred to by its full name, the Tunnel and Reservoir Plan (TARP). But its nickname is apt; at a maximum depth of 350 feet it’s the deepest of the six sets of tunnels we’re treating here. When Chicago’s freight tunnels flooded in 1992, the water was drained into here.
https://www.wbez.org/shows/curious-city/six-tunnels-hidden-under-chicagos-loop/a4a5fc40-fbd6-415e-96b1-29d767363e57