Chicago Magazine reports that 'bomb trains' are rolling through the Windy City

Millions of gallons of highly flammable crude oil roll daily through the busy metropolitan area surrounding Chicago, Chicago Magazine reported.

The so-called "bomb trains," which move along different, top-secret routes, carry mostly Bakken crude - a type known to be particularly explosive.

The trains are usually comprised of traditional tank cars which can carry up to 30,000 gallons each.

While derailments are rare, they're not unheard of. The magazine reported that there were at least 17 such incidents in North America in the previous three years:

In eight of them, the tank cars blew, sending fireballs hundreds of feet into the air, filling the sky with black mushroom clouds. In the most severe cases, the flames produced are so hot that firefighters almost inevitably choose to let them burn out, which can take days, rather than extinguish them. (The Wall Street Journal calculated that a single tank car of sweet crude carries the energy equivalent of two million sticks of dynamite.)

A 63-car derailment in Quebec made headlines in 2013 after its cargo exploded in the middle of a small town, killing 47 and leveling 30 buildings.

New technology such as fracking and horizontal drilling have created an oil boom in the upper Midwest, and without the established pipeline infrastructure already in place to transport oil from the gulf region, producers have no choice but to ship by rail.

Chicago Magazine reported that at least 40 of these trains roll through the city every week, carrying a total of about 17 million gallons of Bakken crude.

For example, according to [the environmental advocacy group Stand], half of Chicago's Bridgeport neighborhood, home to 32,000 people and U.S. Cellular Field, falls squarely within a half-mile "evacuation zone," established by the U.S. Department of Transportation for areas vulnerable to crude oil train explosions.

The United States department of Transportation ordered last year that trains carrying crude oil be limited to no more than 40 MPH when traveling through heavily populated areas, though most trains run at an average of just 30 MPH.

Regulations that require new safety features for tank cars, including thicker steel shells, do not take effect until 2025.

Read the original story in Chicago Magazine here.