The tunnels of Chicago

Artificial caverns under Chicago.  Image via BLDGBLOG and Tunneling Online

Big cities produce, and need, big infrastructure.  Chicago is built in a location that has significant problems with flooding, and in response the city has been building a huge network of storm-drains and sewers at a grand scale.  The TARP (Tunnels and Reservoir Program) project has now built a little over 100 miles of tunnels under the city, varying in width from 8 to 35 feet wide, ultimately leading to reservoirs that will contain billions of gallons of fluids.  And in addition to this, some of the tunnels connect back into a further 60 miles of freight tunnels.

The idea of the “megadungeon” has made something of a return to respectability, but in my mind there is still that nagging doubt about how exactly a largely underground location would come about.  Projects like this suggest a potential origin story – they are remnants of an advanced former civilization.  Post some ancient apocalypse, the city is gone, but its hidden bones remain.

If you think about the areas that have typically been called a “megadungeon”, they will hardly scratch the surface of the monumental scale of a project like this.  Beyond the simple number of 106 miles of tunnels, consider the number of access points or connections back to the service that the system must have as well.  Imagine a tunnel that you would take a day to travel down, and that you could march along it 6 abreast.  Or reservoirs with volumes measured in the hundreds of millions of cubic feet (imagine a cube 300’ x 300’ x 300’, that’s the kind of volume we’re talking about).