DEVELOPING STORY: RED LINE TRAIN DERAILED TO AVOID COLLISION
Sources tell the Washington Post that today's derailment was caused when derailer equipment kicked in to prevent a collision with another train. The Red Line train, headed towards Shady Grove, derailed onto a "pocket track" between the Farragut North and Dupont Circle stations. The Metro source tells WaPo that the derailer kicked in when the train was attempting to pass through a red signal.
Note: Metro's crash-avoidance system does not work using typical signals. Signals on Metro are placed near interlockings (switches). More information as this develops... The NTSB has been dispatched to investigate this morning's accident.
Several questions arise, and remain unanswered at this point: Why would a train attempt to pass through a red signal at an interlocking. Why was the signal red? Was there single-tracking happening in the area? Was there another train in the vicinity (e.g. how close of a call was this?). What parts of Metro's safety system broke down in this instance? I'll be doing complete coverage of this event, and tying it into all of the previous Metro coverage from the past. If anything, this is yet again another example of why Metro needs serious safety reform. It appears at this point that several things went wrong this morning on the Red Line.
What does this mean?
Metro's Automatic Train Protection system should govern all train operations during revenue hours. This system, in theory, prevents a train from entering a block of track that is occupied by another train, or from passing through a red signal at an interlocking. It appears that the Automatic Train Protection system failed, allowing the train to pass through a red signal at an interlocking outside of Farragut North. Equipment present at the interlocking (derailer) kicked in and derailed the train to prevent it from entering a (presumably) occupied section of track, or worse, traveling onto the wrong-way track.