NTSB Issues New Safety Advisory to Metro
The National Transportation Safety Board has issued nine new safety recommendations to Metro and its circuit manufacturer as part of its investigation into the June 22 crash on the Red Line.
The recommendations address concerns about the safety of train control systems, such as Metro's, that use audio frequencies to detect and report the presence in trains. The NTSB considers six of the recommendations urgent.
In its statement today, the NTSB again notes that it has not determined the cause of the crash. But it says that during the investigation, investigators discovered that a failure occurred in which a false signal generated by a track circuit module transmitter mimicked a valid signal and bypassed the rails via an unintended path.
As a result, the stopped train was not detected in the track circuit where the following train crashed into it.
The NTSB wants Metro and Alstom Signaling Inc., the manufacturer of the track circuit modules in the area where the crash occurred, to examine the track circuits and work together to eliminate conditions that could affect their safety. It also urged the transit authority to develop a program to regularly determine that the electronics are working right.
The investigators also are concerned about other rail systems using comparable technology, so the NTSB recommended that the Federal Transit Administration and the
Federal Railroad Administration advise all rail transit operators and railroads that use audio frequency track circuits about these findings.
In the statement, NTSB Chairman Deborah Hersman said: " ... our findings so far indicate a pressing need to issue these recommendations to immediately address safety glitches we have found that could lead to another tragic accident on WMATA or another transit or rail system."
[7:46 p.m. update]
Metro General Manager John B. Catoe said in a statement tonight: "The NTSB has identified a symptom of the problem with the track circuit, but not a root cause or a solution. We are doing everything we can to make our rail system as safe as possible."
He said Metro already has begun work to correct the problem of false signals. "We will continue to cooperate with the NTSB and respond quickly in hope that they can identify a root cause or causes that will allow us to put steps in place to prevent this from happening again," Catoe said in the statement.
Previous recommendations from the NTSB have focused on issues concerning the track circuits. During the summer, Metro said it was raising its standards for acceptable performance of track circuits. That resulted in periodic delays for riders when track circuits were taken out of service and tested. Metro maintains a list of those circuit checks here.
In August, Metro began a project to completely replace the track circuits in the crash zone between Takoma and Fort Totten stations, and train travel is largely back to normal in that area.
All trains continue to be under the control of their operators rather than the automated train control system, as has been the case since the crash.
Here's a link to the letter that the NTSB sent to Metro.
Here's a copy of the letter sent to Alstom.
September 22, 2009; 4:51 PM ET
Categories: Metro , Safety | Tags: Dr. Gridlock, Metrorail, Red Line crash
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