This was the first elevated derailment. It happened in New Jersey, 1923 and they promised that it would never happen again. Fortunately, it did not fall on a lot of people.
"Either write something worth reading or do something worth writing."
The Windy City's most catastrophic rail accident occurred in 1977, when three cars fell off the elevated tracks after two trains collided at the Ravenswood stop downtown.
Chicago had just installed a system that made a train brake automatically if it sensed another one ahead, much like the train in the D.C. accident on Monday should have done. However, Chicago operators back then could override the stop signal if the train was traveling at less than 15 miles per hour. And because "ghost signals" happened occasionally, many drivers did roll past red lights.
The system interpreted the station stop as the required stop, and so the motorman should have been operating under "sight rules." But he didn't. And he didn't even keep his eyes on the track ahead. Fortunately, they did not fall on a lot of people. In the aftermath of this wreck, the Chicago Transit Authority changed the rules and forbade operators from proceeding on their own--from then on they had to call Central Control before continuing through a stop sign.
So it cannot happen again, Right? - - - Wrong.