NTSB Warns of Faulty Transit Safety Systems


The National Transportation Safety Board has warned that city transit systems nationwide may have a flaw that fools the safety system into indicating a track is empty when it is not. This follows the Washington, D.C. rear-end train collision which killed nine people and injured 70.

Though NTSB officials have not determined an exact cause for the June train accident, they discovered a piece of equipment that malfunctioned. This equipment tricked a sensor on the tracks into believing there was no train present. While this piece of equipment was a main factor in the accident by not alerting one train that another was stopped on the tracks, it is unknown how this could have happened.

The NTSB has stated part of the sensor system was replaced in the days before the accident. The board has also stated that managers of the subway system had not responded to earlier system failures.

According to the NTSB, the sensor that was tricked listens for tones which indicate a train is present. These tones are the equivalent of the tones up high in a piano register and are audible to the human ear. It is believed electronic equipment unexpectedly generated these sound waves and traveled to the sensor.

The NTSB has issued nine recommendations, six of them urgent, to the D.C. transit officials, the Federal Railroad Administration, the Federal Railroad Administration, and Alstom Signaling, Inc.