El derailment | What’s up with that?

Since I’ve switched from the straight-shot Red Line to the winding Brown Line, where you often feel like you’re about to ride right off the rails (and right into a nearby condo building), I’ve been wondering: At what speed would El trains hitting sharp curves come off the tracks?

A CTA train’s extremely low center of gravity and speed limits allow it to safely navigate the El’s many curves, according to spokeswoman Catherine Hosinski. As a train goes around a bend, like the tight S-curve on the Brown and Purple Lines just north of the Merchandise Mart, the car may seem to sway at an impossible angle, but most of the weight is still directed straight down, Hosinski says. This overcomes centrifugal force and keeps the wheels on the rails. “Also, a train’s speed through each curve is limited by the automated train control system,” she says. “This system enforces a maximum train speed that’s much lower than the speed that could cause a train to leave the rails.” Despite Hosinski’s assurances that modern CTA cars are safe, over the years the CTA has suffered a number of train plunges (the Green Line in 1966 and ’72). A 1977 incident killed 11: Two trains collided at the Wabash Avenue and Lake Street curve, causing one train to fall off the tracks. “I’m not an apologist for the CTA, but over 10 billion people have ridden the system in its 120-year history and you’re talking about a few dozen fatalities,” says local transit authority Greg Borzo, author of The Chicago “L”, a history of the system. “That’s a pretty good safety record.” Just as Borzo soothed our nerves last week, news broke that the CTA recently purchased hundreds of new 5000 Series rail cars whose faulty craftsmanship could have led to derailments.