WASHINGTON (Reuters) - The U.S. government’s top safety investigator said on Wednesday irregularities were found in the ventilation system of Washington's subway after smoke filled a tunnel and two rail cars last week, killing one passenger and injuring scores.
The disclosure came during a news conference in the U.S. Capitol building to detail the first stages of an accident investigation that could last six months to a year.
"We have tested the ventilation system and noticed some anomalies," Christopher Hart, acting chairman of the National Transportation Safety Board (NTSB), told reporters, though he did not elaborate on the abnormalities discovered.
Minutes before Hart spoke, members of Congress whose home districts are serviced by the Washington area’s transit system, known as Metrorail, said ventilation fans apparently drew smoke into rail cars, where passengers suffered smoke inhalation.
Smoke spewed from electrical arcing that lasted nearly 45 minutes near the busy downtown L’Enfant Plaza station during the Jan. 12 accident. Two trains stopped on the tracks before reaching the station as they filled with smoke.
One woman died and more than 80 other people were overcome by smoke but survived.
Federal investigators have previously said the sparking, or electrical arc, that produced the smoke occurred when a circuit breaker tripped on a section of the electrically charged third rail of the subway's Yellow Line.
"We know there was an arc, but we don’t know why there was an arc," Hart said. Arcing normally results if power lines are touched by a conductor of electricity, such as water.
He said details of ventilation system problems would have to await further investigation.
The safety board is also examining reports of confused radio communications between firefighters and transit dispatchers that might have slowed the emergency response, he said. District of Columbia Fire Department radio transmissions are "encrypted," or electronically coded, to limit access to authorized agencies.
Lawmakers who spoke about the accident on Capitol Hill on Wednesday said Metro has an immediate need for a better ventilation system and improved communications between dispatchers and emergency responders.
"We’re not going to wait for a final report to press and insist on change," said Senator Barbara Mikulski, a Maryland Democrat.
The NTSB investigation will also look into maintenance and aging of the transit system, personnel training, evacuation procedures and air flow in stations and tunnels.
Editing by Steve Gorman and Clarence Fernandez