Signaling Equipment Failed Before Deadly D.C. Metro Crash

Investigators say signaling equipment where a deadly Metro transit train crash occurred periodically failed in the days before last week's accident.

Nine people were killed and more than 70 injured June 22 when a moving train slammed into another train stopped on the tracks near the Maryland state line.

Click here for photos.

Mourners Gather in D.C. Metro Train Operator's Hometown for Funeral

Metro's signaling system is supposed to detect passing trains and transmit speed and stop commands.

But the National Transportation Safety Board said Wednesday that problems began occurring after a piece of equipment was replaced June 17, five days before the crash.

Metro did not immediately respond to a request seeking comment.

The NTSB says the signaling system at the crash site also failed intermittently during tests following the crash.