WASHINGTON - The section of track where two trains collided last week, killing nine people, had been experiencing problems with its train control system since a part had been replaced five days before the crash, the National Transportation Safety Board said in a statement issued Wednesday.

A piece of the track circuit that detects the presence of trains was replaced June 17, five days before the accident. The NTSB said that after the crash WMATA told federal investigators that "the track circuit periodically lost its ability to detect trains after June 17th".

The NTSB tested that section of track last week, finding the circuit could not detect a stopped train. Investigators say further testing over the weekend found intermittent failures of the train control system along the same section of track.

Metro says it only learned of the problem while reviewing records after the crash. The intermittent anomalies would only have shown up in reports issued every thirty days, according to Metro. The only other way Metro could have learned about the intermittent problems was if engineers would have been looking at that particular circuit while it experienced a problem.

The circuit, one of 3,000 in the system, was replaced because of routine maintenance, Metro said, and not because of a problem.

The device in question communicates information such as speed and distance between the tracks, trains and operations control center, Metro said.

Metro said it is now getting daily reports on its 3,000 track circuits and has found no other problems so far.

According to a statement from Metro General Manager John Catoe:

"Our testing has resulted in our being able to replicate the problem, but not isolate the specific cause. We know the problem is in a track circuit. We could just replace the parts, but we need to understand what caused it. You don’t just change the parts. We must find the cause." 

The NTSB says it is reviewing documentation on the performance of that track circuit both before and after the June 17 replacement and is collecting more data about the train control system on that track circuit for further analysis, according to the statement.

The findings by the National Transportation Safety Board are the strongest indication yet that the oncoming train could have lacked information that another train was stopped on the tracks when the June 22 crash occurred.

The cause of the crash, the deadliest in the rail system's 33-year history, has not been determined. 

It's believed the automated train control system may have driven the striking train into the back of the stopped train because the traina control system did not detect the stopped train because of a malfunction.

Investigators found evidence the operator of the striking train, Jeanice McMillan, hit the emergency brakes about 425 feet before the collision. McMillan and eight passengers died in the collision. It remains unclear how fast McMillan's train was traveling when it struck the stopped train.

NTSB investigators plan to return to the section of track on the weekend of July 18 to test sightlines, indicating how much time McMillan would have had to hit the emergency brakes.

 Email To Friend